COLUMBIA BANKING SYSTEM, INC., 10-K filed on 3/1/2018
Annual Report
v3.8.0.1
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2017
Jan. 31, 2018
Jun. 30, 2017
Document Information [Line Items]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Entity Registrant Name COLUMBIA BANKING SYSTEM INC    
Entity Central Index Key 0000887343    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   73,038,791  
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Public Float     $ 2,276,688,279
v3.8.0.1
Consolidated Balance Sheets - USD ($)
shares in Thousands, $ in Thousands
Dec. 31, 2017
Dec. 31, 2016
ASSETS    
Cash and due from banks $ 244,615 $ 193,038
Interest-earning deposits with banks 97,918 31,200
Total cash and cash equivalents 342,533 224,238
Securities available for sale at fair value (amortized cost of $2,768,605 and $2,299,037, respectively) 2,742,831 2,278,577
Federal Home Loan Bank stock at cost 10,440 10,240
Loans held for sale 5,766 5,846
Loans, net of unearned income of ($52,111) and ($33,718), respectively 8,358,657 6,213,423
Loans and Leases Receivable, Allowance 75,646 70,043
Loans, net 8,283,011 6,143,380
FDIC Indemnification Asset 0 3,535
Interest receivable 40,881 30,074
Premises and equipment, net 169,490 150,342
Other real estate owned 13,298 5,998
Goodwill 765,842 382,762
Core deposit intangible, net 58,173 17,631
Other assets 284,621 256,984
Total Assets 12,716,886 9,509,607
LIABILITIES AND SHAREHOLDERS' EQUITY    
Noninterest-bearing 5,081,901 3,944,495
Interest-bearing 5,450,184 4,114,920
Total deposits 10,532,085 8,059,415
Federal Home Loan Bank advances 11,579 6,493
Securities sold under agreements to repurchase 79,059 80,822
Subordinated Debt 35,647 0
Junior Subordinated Notes 8,248 0
Other liabilities 100,346 111,865
Total liabilities 10,766,964 8,258,595
Commitments and contingent liabilities
Preferred Stock, Shares Authorized 2,000 2,000
Preferred Stock, Shares Issued 0 9
Preferred Stock, Value, Issued $ 0 $ 2,217
Shareholders' equity:    
Authorized shares 115,000 115,000
Common Stock Shares Issued And Outstanding 73,020 58,042
Common Stock (no par value) $ 1,634,705 $ 995,837
Retained earnings 337,442 271,957
Accumulated Other Comprehensive Income (Loss), Net of Tax (22,225) (18,999)
Total shareholders' equity 1,949,922 1,251,012
Total Liabilities and Shareholders' Equity $ 12,716,886 $ 9,509,607
v3.8.0.1
Consolidated Balance Sheets (Parenthetical) - USD ($)
shares in Thousands, $ / shares in Thousands, $ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Securities available-for-sale, amortized cost $ 2,768,605 $ 2,299,037
Unearned income on loans $ (52,111) $ (33,718)
Common stock, par value $ 0 $ 0
Common stock, shares authorized 115,000 115,000
Common stock, outstanding 73,020 58,042
v3.8.0.1
Consolidated Statements of Income - USD ($)
shares in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Interest Income      
Loans $ 324,229 $ 291,465 $ 286,166
Taxable securities 38,659 35,167 30,774
Tax-exempt securities 11,045 11,121 11,842
Deposits in banks 813 216 109
Total interest income 374,746 337,969 328,891
Interest Expense      
Deposits 4,800 3,134 2,977
Federal Home Loan Bank advances 1,078 671 474
Interest Expense, Subordinated Notes and Debentures 304 0 0
Other borrowings 575 545 553
Total interest expense 6,757 4,350 4,004
Net Interest Income 367,989 333,619 324,887
Provision for loan and lease losses 8,631 10,778 8,591
Net interest income after provision for loan and lease losses 359,358 322,841 316,296
Noninterest Income      
Deposit account and treasury management fees 30,381 28,500 28,451
Card revenue 25,627 23,620 22,690
Financial services and trust revenue 11,478 11,266 12,596
Loan revenue 12,399 10,967 10,932
Merchant Discount Fees 4,283 8,732 8,975
Investment securities gains (losses), net (11) 1,181 1,581
Gain on sale of merchant card services portfolio 14,000 0 0
Bank owned life insurance 5,380 4,546 4,441
Change in FDIC loss sharing asset (447) (2,585) (4,010)
Other 6,552 1,855 5,817
Total noninterest income 109,642 88,082 91,473
Noninterest Expense      
Compensation and employee benefits 169,674 150,282 149,410
Occupancy 32,407 33,734 34,818
Merchant processing 2,196 4,330 4,204
Advertising and promotion 4,466 4,598 4,713
Data processing 18,205 16,488 17,421
Legal and professional fees 15,151 7,889 9,608
Taxes, licenses and fees 4,773 5,185 5,395
Regulatory premiums 3,183 3,777 4,806
Net cost (benefit) of operation of other real estate owned 468 551 (1,629)
Amortization of intangibles 6,333 5,946 6,882
Other 34,161 28,362 30,521
Total noninterest expense 291,017 261,142 266,149
Income before income taxes 177,983 149,781 141,620
Income tax provision 65,155 44,915 42,793
Net Income $ 112,828 $ 104,866 $ 98,827
Per Common Share      
Basic earnings per common share $ 1.86 [1] $ 1.81 [1] $ 1.71
Diluted earnings per common share $ 1.86 [1] $ 1.81 [1] $ 1.71
Weighted average number of common shares outstanding 59,882 57,184 57,019
Weighted average number of diluted common shares outstanding 59,888 57,193 57,032
[1] Due to averaging of shares, quarterly earnings per share may not add up to the totals reported for the full year.
v3.8.0.1
Consolidated Statements of Comprehensive Income - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Net income $ 112,828 $ 104,866 $ 98,827
Unrealized loss from securities:      
Net unrealized holding loss from available for sale securities arising during the period, net of tax of $1,932, $7,025 and $3,455 (3,391) (12,338) (6,069)
Reclassification adjustment of net gain (loss) from sale of available for sale securities included in income, net of tax of ($4), $429 and $574 7 (752) (1,007)
Net unrealized loss from securities, net of reclassification adjustment (3,384) (13,090) (7,076)
Pension plan liability adjustment:      
Unrecognized net actuarial gain (loss) and plan amendments during the period, net of tax of $2,287, $22 and $2,878 4,017 (39) (5,054)
Less: amortization of unrecognized net actuarial losses included in net periodic pension cost, net of tax of ($127), ($243) and ($122) 223 425 214
Pension plan liability adjustment, net 4,240 386 (4,840)
Other comprehensive income (loss) 856 (12,704) (11,916)
Comprehensive income $ 113,684 $ 92,162 $ 86,911
v3.8.0.1
Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Net unrealized holding gain (loss) from available for sale securities arising during the period, tax $ (1,932) $ (7,025) $ (3,455)
Reclassification adjustment of net gain from sale of available for sale securities included in income, tax (4) 429 574
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax (2,287) 22 2,878
Less: amortization of unrecognized net actuarial loss included in net periodic pension cost, tax $ (127) $ (243) $ (122)
v3.8.0.1
Consolidated Statements of Changes in Shareholders' Equity - USD ($)
$ in Thousands
Total
Preferred Stock [Member]
Common Stock [Member]
Retained Earnings [Member]
Accumulated Other Comprehensive Income [Member]
Balance, value at Dec. 31, 2014 $ 1,228,175 $ 2,217 $ 985,839 $ 234,498 $ 5,621
Balance (in shares) at Dec. 31, 2014   9,000 57,437,000    
Net income 98,827     98,827  
Other comprehensive income (11,916)       (11,916)
Issuance of common stock - stock option and other plans, shares     49,000    
Issuance of common stock - stock option and other plans, value 1,258   $ 1,258    
Issuance of common stock - restricted stock awards, net of canceled awards, shares     270,000    
Issuance of common stock - restricted stock awards, net of canceled awards, value 4,090   $ 4,090    
Purchase and retirement of common stock (in shares)     (32,000)    
Purchase and retirement of common stock, value (906)   $ (906)    
Dividends, Preferred Stock, Cash (137)     (137)  
Cash dividends paid on common stock (77,263)     (77,263)  
Balance, value at Dec. 31, 2015 $ 1,242,128 $ 2,217 $ 990,281 255,925 (6,295)
Balance (in shares) at Dec. 31, 2015   9,000 57,724,000    
Preferred Stock, Dividends, Per Share, Cash Paid $ 1.34        
Common Stock, Dividends, Per Share, Cash Paid $ 1.34        
Net income $ 104,866     104,866  
Other comprehensive income (12,704)       (12,704)
Stock Adjustment Value Deferred Compensation (11)   $ (11)    
Issuance of common stock - stock option and other plans, shares     50,000    
Issuance of common stock - stock option and other plans, value 1,349   $ 1,349    
Issuance of common stock - restricted stock awards, net of canceled awards, shares     306,000    
Issuance of common stock - restricted stock awards, net of canceled awards, value 5,009   $ 5,009    
Tax benefit deficiency associated with share-based compensation 334   $ 334    
Purchase and retirement of common stock (in shares)     (38,000)    
Purchase and retirement of common stock, value (1,125)   $ (1,125)    
Dividends, Preferred Stock, Cash (157)     (157)  
Cash dividends paid on common stock (88,677)     (88,677)  
Balance, value at Dec. 31, 2016 $ 1,251,012 $ 2,217 $ 995,837 271,957 (18,999)
Balance (in shares) at Dec. 31, 2016   9,000 58,042,000    
Preferred Stock, Dividends, Per Share, Cash Paid $ 1.53        
Common Stock, Dividends, Per Share, Cash Paid $ 1.53        
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-09 [Member] $ 67   $ 184 (117)  
Net income 112,828     112,828  
Other comprehensive income 856       856
Issuance of common stock, net of offering costs, shares   0 14,642,000    
Issuance of common stock, net of offering costs, value 636,385 $ 0 $ 636,385    
Stock Adjustment Value Deferred Compensation $ 1   $ 1    
Issuance of common stock - stock option and other plans, shares 2,242   49,000    
Issuance of common stock - stock option and other plans, value $ 1,980   $ 1,980    
Issuance of common stock - restricted stock awards, net of canceled awards, shares     241,000    
Issuance of common stock - restricted stock awards, net of canceled awards, value 7,745   $ 7,745    
Conversion of Stock, Shares Converted   (9,000)      
Conversion of Stock, Amount Converted   $ (2,217)      
Conversion of Stock, Shares Issued     102,000    
Conversion of Stock, Amount Issued 0   $ 2,217    
Purchase and retirement of common stock (in shares)     (56,000)    
Purchase and retirement of common stock, value (2,299)   $ (2,299)    
Stock Redeemed or Called During Period, Value (7,345)   (7,345)    
Cash dividends paid on common stock (51,308)     (51,308)  
Balance, value at Dec. 31, 2017 $ 1,949,922 $ 0 $ 1,634,705 337,442 (22,225)
Balance (in shares) at Dec. 31, 2017   0 73,020,000    
Preferred Stock, Dividends, Per Share, Cash Paid $ 0.00        
Common Stock, Dividends, Per Share, Cash Paid $ 0.88        
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02 [Member] $ 0     $ 4,082 $ (4,082)
v3.8.0.1
Consolidated Statements of Cash Flows - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Cash Flows From Operating Activities      
Net income $ 112,828 $ 104,866 $ 98,827
Adjustments to reconcile net income to net cash provided by operating activities:      
Provision for loan and lease losses 8,631 10,778 8,591
Stock-based compensation expense 7,745 5,009 4,090
Depreciation, amortization and accretion 31,101 34,542 30,312
Investment securities loss (gain), net 11 (1,181) (1,581)
Net realized loss (gain) on sale of premises and equipment, loans held for investment and other assets (139) 157 573
Net gain on sale and valuation adjustments of OREO (495) (629) 2,152
Gain on sale of merchant card services portfolio (14,000) 0 0
Gain (Loss) on Sale of Insurance Block (4,193) 0 0
FDIC loss-sharing agreement early termination, pretax charge 2,409 0 0
Originations of loans held for sale (133,460) (110,467) (75,689)
Proceeds from Sale of Loans Held-for-sale 133,540 109,130 72,296
Deferred income tax expense (benefit) 22,431 1,846 6,367
Net change in:      
Interest receivable (2,980) (2,197) (75)
Interest payable 131 (93) (142)
Other assets (25,471) (15,917) (5,419)
Other liabilities (10,554) 8,745 (1,242)
Net cash provided by operating activities 128,525 145,847 134,756
Cash Flows From Investing Activities      
Payments for (Proceeds from) Loans and Leases (273,927) (402,146) (384,321)
Purchases of securities available for sale (355,607) (569,825) (467,631)
Purchases of premises and equipment (6,495) (4,520) (7,581)
Payments to Acquire Federal Home Loan Bank Stock (92,040) (59,599) (16,760)
Proceeds from FDIC for reimbursement on loss-sharing asset 26 927 4,659
Proceeds from sales of securities available for sale 30,403 124,142 95,375
Proceeds from principal repayments and maturities of securities available for sale 283,874 284,218 283,206
Proceeds from sales of loans held for investment and other assets 12,422 9,643 15,074
Proceeds from sale of merchant card services portfolio 14,000 0 0
Proceeds from Sale of Federal Home Loan Bank Stock 98,924 62,081 37,403
Proceeds from sales of other real estate and other personal property owned 2,590 8,158 19,387
Proceeds from Life Insurance Policy 10,745 0 0
Payment from (to) FDIC to terminate loss-sharing agreements (4,666) 0 0
Payment to FDIC Related to Loss-Sharing Asset (210) (1,632) (1,865)
Net cash received in business combinations 80,472 0 0
Net cash used in investing activities (199,489) (548,553) (423,054)
Cash Flows From Financing Activities      
Net increase (decrease) in deposits 353,797 620,785 514,107
Net decrease in repurchase agreements (3,380) (18,877) (5,381)
Proceeds from exercise of stock options 1,980 1,349 1,258
Proceeds from Federal Home Loan Bank advances 2,301,000 1,392,000 1,702,000
Proceeds from Federal Reserve Bank borrowings 10 10 1,010
Repayment of Federal Home Loan Bank advances (2,397,000) (1,454,000) (1,850,000)
Repayment of Federal Reserve Bank borrowings (10) (10) (1,010)
Payment of preferred stock dividends 0 (157) (137)
Payment of common stock dividends (51,308) (88,677) (77,263)
Repayments of Subordinated Debt 6,186 0 8,248
Payments for Repurchase of Equity (7,345) 0 0
Purchase and retirement of common stock (2,299) (1,125) (906)
Proceeds from excess tax benefit from stock-based compensation 0 (344) 0
Net cash provided by financing activities 189,259 451,642 275,430
Increase (decrease) in cash and cash equivalents 118,295 48,936 (12,868)
Cash and cash equivalents at beginning of period 224,238 175,302 188,170
Supplemental Information:      
Cash paid for interest 6,626 4,444 4,146
Cash paid for income tax 59,071 32,723 30,522
Non-cash investing and financing activities      
Loans transferred to other real estate owned 106 1,047 8,688
Share-based consideration issued in business combinations $ 636,385 $ 0 $ 0
v3.8.0.1
Summary of Significant Accounting Policies
 12 Months Ended
Dec. 31, 2017
Accounting Policies [Abstract]  
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies and Recent Developments
Organization
Columbia Banking System, Inc. (the “Corporation,” “we,” “our,” “Columbia” or the “Company”) is the holding company for Columbia State Bank (“Columbia Bank” or the “Bank”) and Columbia Trust Company (“Columbia Trust”). The Bank provides a full range of financial services through 155 branch locations, including 75 in the State of Washington, 66 in Oregon and 14 in Idaho. Columbia Trust provides fiduciary, agency, trust and related services, and life insurance products. Because the Bank comprises substantially all of the business of the Corporation, references to the “Company” mean the Corporation, the Bank and Columbia Trust together. The Corporation is approved as a bank holding company pursuant to the Gramm-Leach-Bliley Act of 1999.
The Company’s accounting and reporting policies conform to accounting principles generally accepted in the United States of America (“GAAP”) and practices in the financial services industry. To prepare the financial statements in conformity with GAAP, management must make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements, and income and expenses during the reporting period. Circumstances and events that differ significantly from those underlying our estimates and assumptions could cause actual financial results to differ from our estimates. The most significant estimates included in the financial statements relate to the allowance for loan and lease losses, business combinations and goodwill impairment.
The Company has applied its accounting policies and estimation methods consistently in all periods presented in these financial statements (to the periods in which they applied).
Recent Developments
In July 2017, we entered into an asset purchase agreement (the “Agreement”) with a third-party pursuant to which we sold our merchant card services portfolio. In addition, we transitioned our delivery of those services from in-house to an outsourced model. The carrying amount of both assets and liabilities subject to the Agreement was zero. As a result, in the current year, we recorded a $14.0 million gain on sale of the merchant card services portfolio. Under the new business model, we share with the buyer in net merchant services revenue and no longer directly incur merchant processing expenses. Our net revenue share from merchant services is presented in “Card Revenue” in the Consolidated Statements of Income. For the year ended December 31, 2017, that net revenue share was $1.1 million.
Correction of Immaterial Error Related to Prior Periods
In December 2017, the Company recorded a $1.8 million adjustment, of which approximately $700 thousand related to prior periods, to correct an error in the measure of purchase premium amortization on adjustable rate mortgage-backed securities as calculated by a third-party provider. The adjustment reduced interest income from taxable securities and corrected the amortized cost of affected securities. Based upon an evaluation of all relevant factors, management believes the correcting adjustment did not have a material impact on the Company’s current or previously reported results.
Consolidation
The Consolidated Financial Statements of the Company include the accounts of the Corporation and its subsidiaries, including the Bank and Columbia Trust. Intercompany balances and transactions have been eliminated in consolidation.
Cash and cash equivalents
Cash and cash equivalents include cash and due from banks, and interest-bearing balances due from correspondent banks and the Federal Reserve Bank. Cash equivalents have a maturity of 90 days or less at the time of purchase.
Securities
Securities are classified based on management’s intention on the date of purchase. All securities are classified as available for sale and are presented at fair value. Unrealized gains or losses on securities available for sale are excluded from net income but are included as separate components of other comprehensive income, net of taxes. Purchase premiums or discounts on securities available for sale are amortized or accreted into income using the interest method over the terms of the individual securities. The Company performs a quarterly assessment to determine whether a decline in fair value below amortized cost is other-than-temporary. Amortized cost includes adjustments made to the cost of an investment for accretion, amortization, collection of cash and previous other-than temporary impairment recognized in earnings. Other-than-temporary impairment exists when it is probable that the Company will be unable to recover the entire amortized cost basis of the security.
In performing the quarterly assessment for debt securities, management considers whether or not the Company expects to recover the entire amortized cost basis of the security. In addition, management also considers whether it is more likely than not that it will not have to sell the security before recovery of its cost basis. If the Company intends to sell a security or it is more likely than not it will be required to sell a security prior to recovery of its cost basis, the entire amount of impairment is recognized in earnings. If the Company does not intend to sell the security or it is not more likely than not it will be required to sell the security prior to recovery of its cost basis, the credit loss component of impairment is recognized in earnings and impairment associated with non-credit factors, such as market liquidity, is recognized in “Other comprehensive income (loss), net of tax”. A credit loss is the difference between the cost basis of the security and the present value of cash flows expected to be collected, discounted at the security’s effective interest rate at the date of acquisition. The cost basis of an other-than-temporarily impaired security is written down by the amount of impairment recognized in earnings. The new cost basis is not adjusted for subsequent recoveries in fair value. However, the difference between the new amortized cost basis and the cash flows expected to be collected is accreted as interest income. The total other-than-temporary impairment, if any, is presented in the Consolidated Statements of Income with a reduction for the amount of other-than-temporary impairment that is recognized in “Other Comprehensive Income,” if any.
Realized gains or losses on sales of securities available for sale are recorded using the specific identification method.
Federal Home Loan Bank Stock
The Company holds shares of Class B stock issued by the Federal Home Loan Bank of Des Moines (the “FHLB”), which has been designated as FHLB membership stock or FHLB activity based stock in accordance with the capital plan of the FHLB. Membership stock is stock we are required to purchase and hold as a condition of membership in the FHLB. The Company’s membership stock purchase requirement is measured as a percentage of our year-end assets, subject to a $10 million cap. Activity based stock is stock we are required to purchase and hold in order to obtain an advance or participate in FHLB mortgage programs. Class B stock may be redeemed, subject to certain limitations, on five years’ written notice to the FHLB. Our FHLB stock is carried at par value because the shares are issued, transferred, redeemed, and repurchased by the FHLB at a par value of $100. The FHLB stock is subject to recoverability testing per the Financial Services-Depository and Lending topic of the FASB Accounting Standards Codification (“ASC”).
Loans
Loans, excluding purchased credit impaired loans, are generally carried at the unpaid principal balance, net of purchase premiums, purchase discounts and net deferred loan fees. Net deferred loan fees include nonrefundable loan origination fees less direct loan origination costs. Net deferred loan fees, purchase premiums and purchase discounts are amortized into interest income using either the interest method or straight-line method over the terms of the loans, adjusted for actual prepayments. The interest method is used for all loans except revolving loans, for which the straight-line method is used. Interest income is accrued as earned. Fees related to lending activities other than the origination or purchase of loans are recognized as noninterest income during the period the related services are performed.
Nonaccrual loans—Loans are placed on nonaccrual status when a loan becomes contractually past due 90 days with respect to interest or principal unless the loan is both well secured and in the process of collection, or if full collection of interest or principal becomes uncertain. When a loan is placed on nonaccrual status, any accrued and unpaid interest receivable is reversed and the amortization of net deferred loan fees, premiums and discounts ceases. The interest payments received on nonaccrual loans are generally accounted for on the cost-recovery method whereby the interest payment is applied to the principal balances. Loans may be returned to accrual status when improvements in credit quality eliminate the doubt as to the full collectability of both interest and principal and a period of sustained performance has occurred.
Impaired loans—Loans are considered impaired when based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement or when a loan has been modified in a troubled debt restructuring. The assessment for impairment occurs when and while such loans are designated as classified per the Company’s internal risk rating system or when and while such loans are on nonaccrual. All nonaccrual loans greater than $500,000 and all troubled debt restructured loans are considered impaired and analyzed individually on a quarterly basis. Classified loans with an outstanding balance greater than $500,000 are evaluated for potential impairment on a quarterly basis.
Restructured Loans—A loan is classified as a troubled debt restructuring when a borrower is experiencing financial difficulties that lead to a restructuring of the loan, and the Company grants concessions to the borrower in the restructuring that it would not otherwise consider. These concessions may include interest rate reductions, principal forgiveness, extension of maturity date and other actions intended to minimize potential losses. Generally, a nonaccrual loan that is restructured remains on nonaccrual status for a period of six months to demonstrate that the borrower can meet the restructured terms. If the borrower’s performance under the new terms is not reasonably assured, the loan remains classified as a nonaccrual loan.
Purchased Credit Impaired Loans (“PCI Loans”)—Loans acquired with evidence of credit deterioration since origination for which it is probable that all contractually required payments will not be collected are accounted for under ASC 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality. In addition, because of the significant discounts associated with certain of the acquired loan portfolios, the Company elected to account for those certain acquired loans under ASC 310-30.
In situations where such loans have similar risk characteristics, loans are aggregated into pools to estimate cash flows. A pool is accounted for as a single asset with a single interest rate, cumulative loss rate and cash flow expectation. Expected cash flows at the acquisition date in excess of the fair value of loans are considered to be accretable yield, which is recognized as interest income over the life of the loan pool using a level yield method if the timing and amount of the future cash flows of the pool is reasonably estimable. Subsequent to the acquisition date, any increases in cash flow over those expected at purchase date in excess of fair value are recorded as interest income prospectively. Any subsequent decreases in cash flow over those expected at purchase date due to credit deterioration are recognized by recording an allowance for losses on purchased credit impaired loans. Any disposals of loans, including sales of loans, payments in full or foreclosures result in the removal of the loan from the loan pool at the carrying amount.
Unfunded loan commitments—Unfunded commitments are generally related to providing credit facilities to clients of the Bank and are not actively traded financial instruments. These unfunded commitments are disclosed as financial instruments with off-balance sheet risk in Note 18 in the Notes to Consolidated Financial Statements.
Allowance for Loan and Lease Losses
The allowance for loan and lease losses (the “allowance”) is an accounting estimate of incurred credit losses in our loan portfolio at the balance sheet date. The provision for loan and lease losses is the expense recognized in the Consolidated Statements of Income to adjust the allowance to the levels deemed appropriate by management, as measured by the Company’s credit loss estimation methodologies.
Loans Collectively Evaluated for Impairment—This measure of estimated credit losses is based upon the loss experience over a historical base period adjusted for a loss emergence period. The loss emergence period is an estimate of the period that it takes, on average, for us to identify the amount of loss incurred for a loan that has suffered a loss-causing event. Management then considers the effects of the following qualitative factors to ensure our allowance reflects the inherent losses in the loan portfolio:
•
Economic and business conditions;
•
Concentration of credit;
•
Lending management and staff;
•
Lending policies and procedures;
•
Loss and recovery trends;
•
Nature and volume of the portfolio;
•
Trends in problem loans, loan delinquencies and nonaccrual loans;
•
Quality of internal loan review; and
•
External factors.
These qualitative factors have a high degree of subjectivity and changes in any of the factors could have a significant impact on our calculation of the allowance. The qualitative adjustment by loan segment is based upon management's assessment of inherent losses within a range between the weighted historical loss factor by segment and the maximum consecutive quarterly losses in the relevant loss emergence period by segment over the historical base period.
Loan and lease losses are charged against the allowance when management believes the collectability of a loan balance is unlikely. Subsequent recoveries, if any, are credited to the allowance.
Loans Individually Evaluated for Impairment—This measure of estimated credit losses begins if, based upon current information and events, we believe it is probable that we will be unable to collect all amounts due according to the contractual terms of the loan agreement or when a loan has been modified in a troubled debt restructuring. When a loan has been identified as impaired, the amount of impairment will be measured using discounted cash flows, except when it is determined that the remaining source of repayment for the loan is the operation or liquidation of the underlying collateral. In these cases, the current fair value of the collateral, reduced by costs to sell, will be used in place of discounted cash flows. As a final alternative, the observable market price of the debt may be used to assess impairment. Predominantly, the Company uses the fair value of collateral approach based upon a reliable valuation. When the measurement of the impaired loan is less than the recorded amount of the loan, an impairment is recognized by recording a charge-off to the allowance or by designating a specific reserve.
Purchased Credit Impaired Loans—The Company updates its cash flow projections for purchased credit impaired loans accounted for under ASC 310-30 on a quarterly basis. Assumptions utilized in this process include projections related to probability of default, loss severity, prepayment and recovery lag. Projections related to probability of default and prepayment are calculated utilizing a loan migration analysis. The loan migration analysis is a matrix of probability that is used to estimate the probability of a loan pool transitioning into a particular delinquency state given its delinquency state at the re-measurement date. Loss severity factors are based upon either actual charge-off data within the loan pools or industry averages, and recovery lags are based upon the collateral within the loan pools.
Any decreases in expected cash flows after the acquisition date and subsequent measurement periods are recognized by recording a provision for loan losses. See “Purchased Credit Impaired Loans” for further discussion.
Unfunded Commitments and Letters of Credit—The allowance for unfunded commitments is maintained at a level believed by management to be sufficient to absorb estimated probable losses related to these unfunded credit facilities. The determination of the adequacy of the allowance is based on periodic evaluations of the unfunded credit facilities including an assessment of the probability of commitment usage, credit risk factors for loans outstanding to these same customers, and the terms and expiration dates of the unfunded credit facilities. The allowance for unfunded commitments is included in “Other liabilities” on the Consolidated Balance Sheets, with changes to the balance charged against noninterest expense.
Premises and Equipment
Land, buildings, leasehold improvements and equipment are stated at cost less accumulated depreciation and amortization. Gains or losses on dispositions are reflected in current operations. Expenditures for improvements and major renewals are capitalized, and ordinary maintenance, repairs and small purchases are charged to “Occupancy” in the Consolidated Statements of Income. Depreciation and amortization are computed based on the straight-line method over the estimated useful lives of the various classes of assets. The ranges of useful lives for the principal classes of assets are as follows:
Buildings and building improvements
5 to 39 years
Leasehold improvements
Term of lease or useful life, whichever is shorter
Furniture, fixtures and equipment
3 to 7 years
Vehicles
5 years
Computer software
3 to 5 years

Software
Capitalized software is stated at cost, less accumulated amortization. Amortization is computed on a straight-line basis and charged to expense over the estimated useful life of the software, which is generally three years. Capitalized software is included in “Premises and equipment, net” in the Consolidated Balance Sheets.
Other Real Estate Owned
Other real estate owned (“OREO”) is composed of real estate acquired by the Company through either foreclosure or deed in lieu of foreclosure in satisfaction of debt. At acquisition, OREO is recorded at fair value less estimated costs to sell. Any fair value adjustments at acquisition are charged to the allowance, or in the event of a write-up without previous losses charged to the allowance, a credit to earnings is recorded. The fair value of the OREO is based upon current appraisal. Losses that result from the ongoing periodic valuation of these properties are charged to the net cost of operation of OREO in the period in which they are identified. Improvements to the OREO are capitalized and holding costs are charged to the net cost of operation of OREO as incurred.
Goodwill and Intangibles
Net assets of companies acquired in a business combination are recorded at fair value at the date of acquisition. Any excess of the purchase price over the fair value of net assets acquired, including identified intangible assets, is recognized as goodwill. Goodwill is reviewed for potential impairment annually, during the third quarter, or, more frequently, if events or circumstances indicate a potential impairment, at the reporting unit level. A reporting unit is an operating segment or one level below an operating segment for which discrete financial information is available and regularly reviewed by management. The Company consists of a single reporting unit. If the fair value of the reporting unit, including goodwill, is determined to be less than the carrying amount of the reporting unit, a further test is required to measure the amount of impairment. If an impairment loss exists, the carrying amount of goodwill is adjusted to a new cost basis. Subsequent reversal of a previously recognized goodwill impairment loss is prohibited.
Identified intangible assets are amortized on an accelerated basis over the period benefited. Intangible assets are also evaluated for impairment if events and circumstances indicate a possible impairment. Such evaluation is based on undiscounted cash flow projections. At December 31, 2017, intangible assets included in the Consolidated Balance Sheets principally consisted of core deposit intangibles with an original estimated life of 10 years.
Income Taxes
The provision for income taxes includes current and deferred income tax expense on net income adjusted for temporary and permanent differences such as interest income from state and municipal securities and investments in affordable housing tax credits. Deferred tax assets and liabilities are recognized for the expected future tax consequences of existing temporary differences between the financial reporting and tax reporting basis of assets and liabilities using enacted tax laws and rates. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. On a quarterly basis, management evaluates deferred tax assets to determine if these tax benefits are expected to be realized in future periods. This determination is based on facts and circumstances, including the Company’s current and future tax outlook. To the extent a deferred tax asset is no longer considered “more likely than not” to be realized, a valuation allowance is established.
We recognize the tax benefit from uncertain tax positions only if it is more likely than not that the tax positions will be sustained on examination by the tax authorities, based on the technical merits of the position. The tax benefit is measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. We recognize interest and penalties related to unrecognized tax benefits in “Provision for income taxes” in the Consolidated Statements of Income.
Advertising
Advertising costs are generally expensed as incurred.
Earnings per Common Share
The Company’s capital structure includes common shares, restricted common share awards, common share options, and, during 2015, 2016 and a portion of 2017, convertible preferred shares. Restricted common share awards participate in dividends declared on common shares at the same rate as common shares. Convertible preferred shares participated in dividends declared on common shares on an “as if converted” basis. Restricted common share awards and convertible preferred shares are considered participating securities under the Earnings per Share topic of the FASB ASC.
The Company calculates earnings per common share (“EPS”) using the two-class method. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common shareholders but does not require the presentation of basic and diluted EPS for securities other than common shares. Under the two-class method, basic EPS is computed by dividing earnings allocated to common shareholders by the weighted average number of common shares outstanding for the period. Earnings allocated to common shareholders represents net income reduced by earnings allocated to participating securities. Diluted EPS is computed in the same manner as basic earnings per share except that the denominator is increased to include the number of additional common shares that would have been outstanding if certain shares issuable upon exercise of common share options were included unless those additional shares would have been anti-dilutive. For the diluted EPS computation, the treasury stock method is applied and compared to the two-class method and whichever method results in a more dilutive impact is utilized to calculate diluted EPS.
Share-Based Payment
The Company accounts for stock options and stock awards in accordance with the Compensation—Stock Compensation topic of the FASB ASC. Authoritative guidance requires the Company to measure the cost of employee services received in exchange for an award of equity instruments, such as stock options or stock awards, based on the fair value of the award on the grant date. This cost must be recognized in the Consolidated Statements of Income over the vesting period of the award.
The Company issues restricted common share awards which generally vest over a four or five-year period during which time the holder receives dividends and has full voting rights. Restricted stock is valued at the closing price of the Company’s stock on the date of an award.
Derivatives and Hedging Activities
In accordance with the Derivatives and Hedging topic of the FASB ASC, the Company recognizes derivatives as assets or liabilities on the Consolidated Balance Sheets at their fair value. The Company periodically enters into interest rate contracts with customers and offsetting contracts with third parties. As these interest rate contracts are not designated as hedges under the Derivatives and Hedging topic of the FASB ASC, the changes in fair value of these instruments are recognized immediately in earnings.
Accounting Pronouncements Recently Issued
In February 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The amendments in this ASU allow a reclassification from accumulated other comprehensive income (“AOCI”) to retained earnings for stranded tax effects in AOCI resulting from the newly enacted corporate tax rate in the Tax Cuts and Jobs Act. The amendments in ASU 2018-02 are effective for fiscal years beginning after December 15, 2018 and interim periods within those years and early adoption is permitted for public business entities in a period for which financial statements have not yet been issued. The Company adopted the amendments of ASU 2018-02 effective December 31, 2017. An election was made to reclassify, using the portfolio approach, deferred taxes recorded in AOCI of $4.1 million to retained earnings.
In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting. The amendments in this ASU provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The amendments in ASU 2017-09 are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted. The adoption of ASU 2017-09 is not expected to have a material impact on the Company’s consolidated financial statements.
In March 2017, the FASB issued ASU 2017-08, Premium Amortization on Purchased Callable Debt Securities. The amendments included in this ASU change guidance on the amortization period of premiums on certain purchased callable debt securities. Specifically, the amendments shorten the premium amortization period to the earliest call date. The amendments in ASU 2017-08 are effective for fiscal years and interim periods within those years, beginning after December 15, 2018. Early adoption is permitted. The Company adopted the amendments of ASU 2017-08 during the first quarter of 2017. The impact of the adoption of ASU 2017-08 to net income and opening retained earnings was not material.
In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment. The amendments in this are intended to reduce the cost and complexity of the goodwill impairment test by eliminating the second step of the goodwill impairment test. An entity will apply a one-step quantitative test and record the amount of goodwill impairment as the excess of a reporting unit’s carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. The new guidance does not amend the optional qualitative assessment of goodwill impairment. The amendments in ASU 2017-04 are effective for annual or interim periods beginning after December 15, 2019. Early adoption is permitted. The adoption of ASU 2017-04 is not expected to have a material impact on the Company’s consolidated financial statements.
In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments. The amendments in this ASU provide specific guidance on several statement of cash flow classification issues to reduce diversity in practice. The amendments in ASU 2016-15 are effective for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption is permitted. The Company adopted the amendments of ASU 2016-15 during 2017. The adoption did not have a material impact to prior year Consolidated Financial Statements.
In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments. The amendments included in this ASU require an entity to reflect its current estimate of all expected credit losses for assets held at an amortized cost basis. For available for sale debt securities, credit losses will be measured in a manner similar to current GAAP, however, this ASU will require that credit losses be presented as an allowance rather than as a write-down. The amendments in ASU 2016-13 are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and are required to be adopted through a modified retrospective approach, with a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the ASU is effective.
Currently, the Company cannot reasonably estimate the impact that adoption of ASU 2016-13 will have on its Consolidated Financial Statements; however, the impact may be significant. That assessment is based upon the fact that, unlike the incurred loss models in existing GAAP, the current expected credit loss (“CECL”) model in ASU 2016-13 does not specify a threshold for the recognition of an impairment allowance. Rather, the Company will recognize an impairment allowance equal to its estimate of lifetime expected credit losses, adjusted for prepayments, for in-scope financial instruments as of the end of the reporting period. Accordingly, the impairment allowance measured under the CECL model could increase significantly from the impairment allowance measured under the Company’s existing incurred loss model. Significant CECL implementation matters to be addressed by the Company include selecting loss estimation methodologies, identifying, sourcing and storing data, addressing data gaps, defining a reasonable and supportable forecast period, selecting historical loss information which will be reverted to, documenting the CECL estimation process, assessing the impact to internal controls over financial reporting, capital planning and seeking process approval from audit and regulatory stakeholders.
In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. The amendments included in this ASU simplify several aspects of the accounting for employee share-based payment transactions including the accounting for income taxes, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. The Company adopted the amendments of ASU 2016-09 at the beginning of 2017. Adoption of amended forfeiture guidance resulted in an opening period adjustment decreasing retained earnings $117 thousand and increasing common stock $184 thousand. Adoption of the amended excess tax benefit guidance resulted in an income tax benefit of $1.3 million or $0.02 per diluted common share for the year ended December 31, 2017.
In February 2016, the FASB issued ASU 2016-02, Leases. The amendments included in this ASU create a new accounting model for both lessees and lessors. The new guidance requires lessees to recognize lease liabilities, initially measured as the present value of future lease payments, and corresponding right-of-use assets for all leases with lease terms greater than 12 months. This model differs from the current lease accounting model, which does not require such lease liabilities and corresponding right-of-use assets to be recorded for operating leases. The amendments in ASU 2016-02 must be adopted using the modified retrospective approach and will be effective for the first interim or annual period beginning after December 15, 2018. Early adoption is permitted. During 2017, the Company selected a third-party lease accounting application to assist in the implementation of this new guidance. Significant implementation matters to be addressed by the Company include assessing the impact to our internal controls over financial reporting and documenting the new lease accounting process. The Company is assessing the impact that this guidance will have on its Consolidated Financial Statements. See Note 18, “Commitments and Contingent Liabilities,” for more information regarding the minimum future payments related to our operating leases.
In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities. The amendments in ASU 2016-01 require all equity investments to be measured at fair value with changes in the fair value recognized through net income. The amendments in ASU 2016-01 also require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. In addition, the amendments in this update eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet for public business entities. The amendments in ASU 2016-01 are effective for the first interim or annual period beginning after December 15, 2017. The Company has assessed the impact that this guidance will have on its consolidated financial statements and determined that the impact will not be material. The change in fair value of equity securities recognized in other comprehensive income was $3 thousand, $33 thousand and $64 thousand for the years ended December 31, 2017, 2016 and 2015, respectively.
In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The guidance in this update will replace most existing revenue recognition guidance in GAAP when it becomes effective. For public companies, this update was to be effective for interim and annual periods beginning after December 15, 2016. However, in August 2015, the FASB issued ASU 2015-14, which delayed the effective date of ASU 2014-09 by one year and permits companies to voluntarily adopt the new standard as of the original effective date. The FASB subsequently issued ASU 2016-08, ASU 2016-10, ASU 2016-12 and ASU 2017-13 to provide implementation guidance and practical expedients related to ASU 2014-09. The Company’s revenue is comprised of interest income on financial assets, which is excluded from the scope of this new guidance, and non-interest income. The adoption of ASU 2017-04 is not expected to have a material impact on the Company’s consolidated financial statements.
v3.8.0.1
Business Combinations
 12 Months Ended
Dec. 31, 2017
Business Acquisition [Line Items]  
Business Combination Disclosure [Text Block]
Business Combinations
Pacific Continental Corporation
On November 1, 2017, the Company completed its acquisition of Pacific Continental Corporation (“Pacific Continental”) and its wholly-owned banking subsidiary Pacific Continental Bank. The Company acquired 100% of the equity interests of Pacific Continental. The primary reasons for the acquisition were to expand in the Eugene, Oregon market and improve branch network efficiencies in the Seattle and Portland markets.
The assets acquired and liabilities assumed have been accounted for under the acquisition method of accounting. The assets and liabilities, both tangible and intangible, were recorded at their fair values as of the November 1, 2017 acquisition date. Initial accounting for deferred taxes was incomplete as of December 31, 2017. The deferred taxes currently recognized in the financial statements have been determined provisionally as the final Pacific Continental tax return has not yet been completed. The application of the acquisition method of accounting resulted in the recognition of goodwill of $383.1 million and a core deposit intangible of $46.9 million, or 2.34% of core deposits. The goodwill represents the excess purchase price over the fair value of the net assets acquired. The goodwill is not deductible for income tax purposes.
The table below summarizes the amounts recognized as of the acquisition date for each major class of assets acquired and liabilities assumed:
 
 
November 1, 2017
 
 
(in thousands)
 
 
 
 
 
Merger consideration
 
 
 
$
637,103

Identifiable net assets acquired, at fair value
 
 
 
 
Assets acquired
 
 
 
 
Cash and cash equivalents
 
$
81,190

 
 
Investment Securities
 
449,291

 
 
Federal Home Loan Bank stock
 
7,084

 
 
Loans
 
1,873,987

 
 
Interest receivable
 
7,827

 
 
Premises and equipment
 
27,343

 
 
Other real estate owned
 
10,279

 
 
Core deposit intangible
 
46,875

 
 
Other assets
 
50,638

 
 
   Total assets acquired
 
 
 
2,554,514

Liabilities assumed
 
 
 
 
Deposits
 
(2,118,982
)
 
 
Federal Home Loan Bank advances
 
(101,127
)
 
 
Subordinated debentures
 
(35,678
)
 
 
Junior subordinated debentures
 
(14,434
)
 
 
Securities sold under agreements to repurchase
 
(1,617
)
 
 
Other liabilities
 
(28,653
)
 
 
Total liabilities assumed
 
 
 
(2,300,491
)
Total fair value of identifiable net assets, at fair value
 
 
 
254,023

Goodwill
 
 
 
$
383,080


See Note 10, “Goodwill and Other Intangible Assets,” for further discussion of the accounting for goodwill and other intangible assets.
The operating results of the Company reported herein include the operating results produced by the acquired assets and assumed liabilities for the period November 1, 2017 to December 31, 2017. Disclosure of the amount of Pacific Continental’s revenue and net income (excluding integration costs) included in Columbia’s Consolidated Statements of Income is impracticable due to the integration of the operations and accounting for this acquisition.
For illustrative purposes only, the following table presents certain unaudited pro forma information for the years ended December 31, 2017 and 2016. This unaudited estimated pro forma financial information was calculated as if Pacific Continental had been acquired as of the beginning of the year prior to the date of acquisition. This unaudited pro forma information combines the historical results of Pacific Continental with the Company’s consolidated historical results and includes certain adjustments reflecting the estimated impact of certain fair value adjustments for the respective periods. The pro forma information is not indicative of what would have occurred had the acquisition occurred as of the beginning of the year prior to the acquisition. In particular, no adjustments have been made to eliminate the impact of other-than-temporary impairment losses and losses recognized on the sale of securities that may not have been necessary had the investment securities been recorded at fair value as of the beginning of the year prior to the date of acquisition. The unaudited pro forma information does not consider any changes to the provision for credit losses resulting from recording loan assets at fair value. Additionally, Columbia expects to achieve further operating cost savings and other business synergies, including revenue growth as a result of the acquisition, which are not reflected in the pro forma amounts that follow. As a result, actual amounts would have differed from the unaudited pro forma information presented.
 
 
Unaudited Pro Forma
 
 
Years Ended December 31,
 
 
2017
 
2016
 
 
(in thousands except per share)
Total revenues (net interest income plus noninterest income)
 
$
571,944

 
$
520,419

Net income
 
$
149,859

 
$
124,550

Earnings per share - basic
 
$
2.23

 
$
1.86

Earnings per share - diluted
 
$
2.23

 
$
1.86


The following table shows the impact of the acquisition-related expenses related to the acquisition of Pacific Continental for the periods indicated to the various components of noninterest expense:
 
 
Year ended December 31,
 
 
2017
 
2016
 
 
(in thousands)
Noninterest Expense
 
 
 
 
Compensation and employee benefits
 
$
8,014

 
$
—

Occupancy
 
1,912

 
—

Advertising and promotion
 
467

 
—

Data processing
 
1,555

 
—

Legal and professional fees
 
4,618

 
291

Taxes, licenses and fees
 
10

 
—

Other
 
620

 
—

Total impact of acquisition-related costs to noninterest expense
 
$
17,196

 
$
291


As a result of the acquisition of Pacific Continental, we have consolidated assets exceeding $10 billion and we will be subject to the interchange fee cap beginning July 1, 2018. We currently anticipate a pre-tax annual impact of approximately $10 million because we will no longer qualify for the small issuer exemption.
v3.8.0.1
Cash and Cash Equivalents
 12 Months Ended
Dec. 31, 2017
Cash and Cash Equivalents [Abstract]  
Cash and Cash Equivalents
Cash and Cash Equivalents
The Company is required to maintain an average reserve balance with the Federal Reserve Bank or maintain such reserve balance in the form of cash. The average required reserve balance for the years ended December 31, 2017 and 2016 was approximately $76.5 million and $62.8 million, respectively, and was met by holding cash and maintaining an average balance with the Federal Reserve Bank.
v3.8.0.1
Securities
 12 Months Ended
Dec. 31, 2017
Available-for-sale Securities [Abstract]  
Securities
Securities
At December 31, 2017 the Company’s securities portfolio primarily consisted of securities issued by the U.S. government, U.S. government agencies, U.S. government-sponsored enterprises and state and municipalities. All of the Company’s mortgage-backed securities and collateralized mortgage obligations are issued by U.S. government agencies and U.S. government-sponsored enterprises and are implicitly guaranteed by the U.S. government. The Company had no other issuances in its portfolio which exceeded ten percent of shareholders’ equity.
The following table summarizes the amortized cost, gross unrealized gains and losses and the resulting fair value of securities available for sale:
 
 
Amortized
Cost
 
Gross
Unrealized
Gains
 
Gross
Unrealized
Losses
 
Fair Value
December 31, 2017
 
(in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
1,752,236

 
$
1,815

 
$
(27,326
)
 
$
1,726,725

State and municipal securities
 
593,940

 
6,023

 
(3,959
)
 
596,004

U.S. government agency and government-sponsored enterprise securities
 
416,894

 
642

 
(2,762
)
 
414,774

U.S. government securities
 
251

 
—

 
(3
)
 
248

Other securities
 
5,284

 
84

 
(288
)
 
5,080

Total
 
$
2,768,605

 
$
8,564

 
$
(34,338
)
 
$
2,742,831

December 31, 2016
 
 
 
 
 
 
 
 
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
1,486,690

 
$
2,760

 
$
(23,718
)
 
$
1,465,732

State and municipal securities
 
473,914

 
6,343

 
(5,197
)
 
475,060

U.S. government agency and government-sponsored enterprise securities
 
332,348

 
1,065

 
(1,511
)
 
331,902

U.S. government securities
 
801

 
—

 
(1
)
 
800

Other securities
 
5,284

 
63

 
(264
)
 
5,083

Total
 
$
2,299,037

 
$
10,231

 
$
(30,691
)
 
$
2,278,577


The following table provides the proceeds and gross realized gains and losses on the sales and calls of securities for the periods indicated:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Proceeds from sales and calls of available for sale securities
 
$
30,403

 
$
124,142

 
$
95,375

 
 
 
 
 
 
 
Gross realized gains
 
$
111

 
$
1,181

 
$
1,591

Gross realized losses
 
(122
)
 
—

 
(10
)
Net realized gains
 
$
(11
)
 
$
1,181

 
$
1,581


The scheduled contractual maturities of investment securities available for sale at December 31, 2017 are presented as follows:
 
 
December 31, 2017
 
 
Amortized Cost
 
Fair Value
 
 
(in thousands)
Due within one year
 
$
124,885

 
$
124,763

Due after one year through five years
 
638,921

 
636,860

Due after five years through ten years
 
804,462

 
796,611

Due after ten years
 
1,195,053

 
1,179,517

Other securities with no stated maturity
 
5,284

 
5,080

Total investment securities available-for-sale
 
$
2,768,605

 
$
2,742,831


The following table summarizes the carrying value of securities pledged as collateral to secure public deposits, borrowings and other purposes as permitted or required by law:
 
 
December 31, 2017
 
December 31, 2016
 
 
(in thousands)
Washington and Oregon State to secure public deposits
 
$
245,222

 
$
232,714

Federal Reserve Bank to secure borrowings
 
52,917

 
33,825

Other securities pledged
 
121,244

 
132,350

Total securities pledged as collateral
 
$
419,383

 
$
398,889

The following tables show the gross unrealized losses and fair value of the Company’s investments with unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at December 31, 2017 and 2016:
 
 
Less than 12 Months
 
12 Months or More
 
Total
 
 
Fair
Value
 
Unrealized
Losses
 
Fair
Value
 
Unrealized
Losses
 
Fair
Value
 
Unrealized
Losses
December 31, 2017
 
(in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
816,678

 
$
(6,710
)
 
$
717,211

 
$
(20,616
)
 
$
1,533,889

 
(27,326
)
State and municipal securities
 
220,019

 
(1,723
)
 
75,172

 
(2,236
)
 
295,191

 
(3,959
)
U.S. government agency and government-sponsored enterprise securities
 
184,046

 
(1,006
)
 
155,983

 
(1,756
)
 
340,029

 
(2,762
)
U.S. government securities
 
249

 
(3
)
 
—

 
—

 
249

 
(3
)
Other securities
 
—

 
—

 
4,982

 
(288
)
 
4,982

 
(288
)
Total
 
$
1,220,992

 
$
(9,442
)
 
$
953,348

 
$
(24,896
)
 
$
2,174,340

 
$
(34,338
)
December 31, 2016
 
 
 
 
 
 
 
 
 
 
 
 
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
1,029,116

 
$
(18,788
)
 
$
159,046

 
$
(4,930
)
 
$
1,188,162

 
$
(23,718
)
State and municipal securities
 
211,342

 
(5,064
)
 
3,384

 
(133
)
 
214,726

 
(5,197
)
U.S. government agency and government-sponsored enterprise securities
 
218,811

 
(1,511
)
 
—

 
—

 
218,811

 
(1,511
)
U.S. government securities
 
251

 
(1
)
 
—

 
—

 
251

 
(1
)
Other securities
 
2,263

 
(51
)
 
2,743

 
(213
)
 
5,006

 
(264
)
Total
 
$
1,461,783

 
$
(25,415
)
 
$
165,173

 
$
(5,276
)
 
$
1,626,956

 
$
(30,691
)

At December 31, 2017, there were 396 U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations securities in an unrealized loss position, of which 120 were in a continuous loss position for 12 months or more. The decline in fair value is attributable to changes in interest rates relative to where these investments fall within the yield curve and their individual characteristics. Because the Company does not currently intend to sell these securities nor does the Company consider it more likely than not that it will be required to sell these securities before the recovery of amortized cost basis, which may be upon maturity, the Company does not consider these investments to be other-than-temporarily impaired at December 31, 2017.
At December 31, 2017, there were 314 state and municipal government securities in an unrealized loss position, of which 69 were in a continuous loss position for 12 months or more. The unrealized losses on state and municipal securities were caused by interest rate changes or widening of market spreads subsequent to the purchase of the individual securities. Management monitors published credit ratings of these securities for adverse changes. As of December 31, 2017, none of the rated obligations of state and local government entities held by the Company had a below investment grade credit rating. Because the credit quality of these securities is investment grade and the Company does not currently intend to sell these securities nor does the Company consider it more likely than not that it will be required to sell these securities before the recovery of amortized cost basis, which may be upon maturity, the Company does not consider these investments to be other-than-temporarily impaired at December 31, 2017.
At December 31, 2017, there were 44 U.S. government agency and government-sponsored enterprise securities in an unrealized loss position, of which 16 were in a continuous loss position for 12 months or more. The decline in fair value is attributable to changes in interest rates relative to where these investments fall within the yield curve and their individual characteristics. Because the Company does not currently intend to sell these securities nor does the Company consider it more likely than not that it will be required to sell these securities before the recovery of amortized cost basis, which may be upon maturity, the Company does not consider these investments to be other-than-temporarily impaired at December 31, 2017.
At December 31, 2017, there was one U.S. government security in an unrealized loss position, which was not in a continuous loss position for 12 months or more. The decline in fair value is attributable to changes in interest rates relative to where this investment falls within the yield curve and its individual characteristics. Because the Company does not currently intend to sell this security nor does the Company consider it more likely than not that it will be required to sell this security before the recovery of amortized cost basis, which may be upon maturity, the Company does not consider this investment to be other-than-temporarily impaired at December 31, 2017.
At December 31, 2017, there were two other securities in an unrealized loss position, both were mortgage-backed securities funds and in a continuous unrealized loss position for 12 months or more. The decline in fair value is attributable to changes in interest rates and the additional risk premium investors are demanding for investment securities with these characteristics. The Company does not consider these investments to be other-than-temporarily impaired at December 31, 2017 as it has the intent and ability to hold the investments for sufficient time to allow for recovery in the market value.
v3.8.0.1
Loans
 12 Months Ended
Dec. 31, 2017
Loans Receivable, Net [Abstract]  
Financing Receivables [Text Block]
Loans
The Company’s loan portfolio includes originated and purchased loans. Originated loans and purchased loans for which there was no evidence of credit deterioration at their acquisition date and it was probable that we would be able to collect all contractually required payments are referred to collectively as loans, excluding purchased credit impaired loans. Purchased loans for which there was, at acquisition date, evidence of credit deterioration since their origination and it was probable that we would be unable to collect all contractually required payments are referred to as purchased credit impaired loans, or “PCI loans.”
The following is an analysis of the loan portfolio by segment (net of unearned income):
 
 
December 31, 2017
 
December 31, 2016
 
 
Loans, excluding PCI loans
 
PCI Loans
 
Total
 
Loans, excluding PCI loans
 
PCI Loans
 
Total
 
 
(in thousands)
Commercial business
 
$
3,377,324

 
$
12,628

 
$
3,389,952

 
$
2,551,054

 
$
20,185

 
$
2,571,239

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
188,396

 
12,395

 
200,791

 
170,331

 
17,862

 
188,193

Commercial and multifamily residential
 
3,825,739

 
75,594

 
3,901,333

 
2,719,830

 
89,231

 
2,809,061

Total real estate
 
4,014,135

 
87,989

 
4,102,124

 
2,890,161

 
107,093

 
2,997,254

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
200,518

 
177

 
200,695

 
121,887

 
832

 
122,719

Commercial and multifamily residential
 
371,931

 
607

 
372,538

 
209,118

 
1,565

 
210,683

Total real estate construction
 
572,449

 
784

 
573,233

 
331,005

 
2,397

 
333,402

Consumer
 
334,190

 
11,269

 
345,459

 
329,261

 
15,985

 
345,246

Less: Net unearned income
 
(52,111
)
 
—

 
(52,111
)
 
(33,718
)
 
—

 
(33,718
)
Total loans, net of unearned income
 
8,245,987

 
112,670

 
8,358,657

 
6,067,763

 
145,660

 
6,213,423

Less: Allowance for loan and lease losses
 
(68,739
)
 
(6,907
)
 
(75,646
)
 
(59,528
)
 
(10,515
)
 
(70,043
)
Total loans, net
 
$
8,177,248

 
$
105,763

 
$
8,283,011

 
$
6,008,235

 
$
135,145

 
$
6,143,380

Loans held for sale
 
$
5,766

 
$
—

 
$
5,766

 
$
5,846

 
$
—

 
$
5,846


At December 31, 2017 and 2016, the Company had no material foreign activities. Substantially all of the Company’s loans and unfunded commitments are geographically concentrated in its service areas within the states of Washington, Oregon and Idaho.
The Company has made loans to executive officers and directors of the Company and related interests. These loans are made on the same terms, including interest rates and collateral, as those prevailing at the time for comparable transactions with unrelated persons and do not involve more than the normal risk of collectability. The aggregate dollar amount of these loans was $10.0 million and $10.1 million at December 31, 2017 and 2016, respectively. During 2017, advances on related party loans totaled $203 thousand and repayments on related party loans totaled $350 thousand.
At December 31, 2017 and 2016, $2.25 billion and $2.29 billion of commercial and residential real estate loans were pledged as collateral on Federal Home Loan Bank advances. The Company has also pledged $70.2 million and $54.2 million of commercial loans to the Federal Reserve Bank for additional borrowing capacity at December 31, 2017 and 2016, respectively.
Nonaccrual loans totaled $66.2 million and $27.8 million at December 31, 2017 and 2016, respectively. The amount of interest income foregone as a result of these loans being placed on nonaccrual status totaled $2.4 million for 2017, $1.9 million for 2016 and $1.3 million for 2015. There were $581 thousand of loans 90 days past due and still accruing interest as of December 31, 2017 and no loans 90 days past due and still accruing interest as of December 31, 2016. At December 31, 2017 and 2016, there were $2.0 million and $293 thousand, respectively, of commitments of additional funds for loans accounted for on a nonaccrual basis.
The following is an analysis of nonaccrual loans as of December 31, 2017 and 2016:
 
 
December 31, 2017
 
December 31, 2016
 
 
Recorded
Investment
Nonaccrual
Loans
 
Unpaid Principal
Balance
Nonaccrual
Loans
 
Recorded
Investment
Nonaccrual
Loans
 
Unpaid Principal
Balance
Nonaccrual
Loans
 
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
Secured
 
$
45,410

 
$
56,865

 
$
11,524

 
$
21,503

Unsecured
 
50

 
49

 
31

 
303

Real estate:
 
 
 
 
 
 
 
 
One-to-four family residential
 
785

 
1,182

 
568

 
1,302

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
Commercial land
 
2,628

 
2,623

 
934

 
922

Income property
 
4,284

 
5,410

 
4,005

 
4,247

Owner occupied
 
7,029

 
7,270

 
6,248

 
9,030

Real estate construction:
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
Land and acquisition
 
25

 
26

 
14

 
102

Residential construction
 
1,829

 
1,828

 
549

 
549

Consumer
 
4,149

 
4,633

 
3,883

 
4,331

Total
 
$
66,189

 
$
79,886

 
$
27,756

 
$
42,289


Loans, excluding purchased credit impaired loans
The following is an aging of the recorded investment of the loan portfolio as of December 31, 2017 and 2016:
 
 
Current
Loans
 
30 - 59
Days
Past Due
 
60 - 89
Days
Past Due
 
Greater
than 90
Days Past
Due
 
Total
Past Due
 
Nonaccrual
Loans
 
Total Loans
December 31, 2017
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
3,185,321

 
$
2,530

 
$
2,400

 
$
—

 
$
4,930

 
$
45,410

 
$
3,235,661

Unsecured
 
123,524

 
100

 
501

 
—

 
601

 
50

 
124,175

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
184,256

 
1,111

 
402

 
—

 
1,513

 
785

 
186,554

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
292,680

 
92

 
—

 
581

 
673

 
2,628

 
295,981

Income property
 
1,898,655

 
2,426

 
971

 
—

 
3,397

 
4,284

 
1,906,336

Owner occupied
 
1,590,004

 
2,485

 
468

 
—

 
2,953

 
7,029

 
1,599,986

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
9,882

 
—

 
—

 
—

 
—

 
25

 
9,907

Residential construction
 
187,862

 
—

 
—

 
—

 
—

 
1,829

 
189,691

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
293,028

 
—

 
—

 
—

 
—

 
—

 
293,028

Owner occupied
 
72,443

 
—

 
—

 
—

 
—

 
—

 
72,443

Consumer
 
325,928

 
1,446

 
702

 
—

 
2,148

 
4,149

 
332,225

Total
 
$
8,163,583

 
$
10,190

 
$
5,444

 
$
581

 
$
16,215

 
$
66,189

 
$
8,245,987

 
 
Current
Loans
 
30 - 59
Days
Past Due
 
60 - 89
Days
Past Due
 
Greater
than 90
Days Past
Due
 
Total
Past Due
 
Nonaccrual
Loans
 
Total Loans
December 31, 2016
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
2,439,250

 
$
806

 
$
10

 
$
—

 
$
816

 
$
11,524

 
$
2,451,590

Unsecured
 
94,118

 
287

 
301

 
—

 
588

 
31

 
94,737

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
164,416

 
2,448

 
500

 
—

 
2,948

 
568

 
167,932

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
269,816

 
64

 
—

 
—

 
64

 
934

 
270,814

Income property
 
1,365,150

 
480

 
111

 
—

 
591

 
4,005

 
1,369,746

Owner occupied
 
1,052,078

 
1,652

 
—

 
—

 
1,652

 
6,248

 
1,059,978

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
11,542

 
—

 
—

 
—

 
—

 
14

 
11,556

Residential construction
 
109,080

 
—

 
—

 
—

 
—

 
549

 
109,629

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
103,779

 
—

 
—

 
—

 
—

 
—

 
103,779

Owner occupied
 
103,480

 
—

 
—

 
—

 
—

 
—

 
103,480

Consumer
 
318,369

 
2,035

 
235

 
—

 
2,270

 
3,883

 
324,522

Total
 
$
6,031,078

 
$
7,772

 
$
1,157

 
$
—

 
$
8,929

 
$
27,756

 
$
6,067,763


The following is an analysis of the impaired loans (see Note 1) as of December 31, 2017 and 2016:
 
 
Recorded Investment
of Loans
Collectively Measured
for Contingency
Provision
 
Recorded Investment
of Loans
Individually
Measured for
Specific
Impairment
 
Impaired Loans With
Recorded Allowance
 
Impaired Loans Without
Recorded Allowance
 
 
Recorded
Investment
 
Unpaid
Principal
Balance
 
Related
Allowance
 
Recorded
Investment
 
Unpaid
Principal
Balance
December 31, 2017
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
3,195,649

 
$
40,012

 
$
3,808

 
$
3,937

 
$
1,867

 
$
36,204

 
$
42,314

Unsecured
 
124,150

 
25

 
25

 
24

 
3

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
185,659

 
895

 
867

 
1,408

 
103

 
28

 
337

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
293,694

 
2,287

 
—

 
—

 
—

 
2,287

 
2,282

Income property
 
1,901,313

 
5,023

 
2,768

 
3,328

 
185

 
2,255

 
2,601

Owner occupied
 
1,591,298

 
8,688

 
77

 
80

 
3

 
8,611

 
10,077

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
9,907

 
—

 
—

 
—

 
—

 
—

 
—

Residential construction
 
188,481

 
1,210

 
—

 
—

 
—

 
1,210

 
1,210

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
293,028

 
—

 
—

 
—

 
—

 
—

 
—

Owner occupied
 
68,393

 
4,050

 
—

 
—

 
—

 
4,050

 
4,050

Consumer
 
325,210

 
7,015

 
5,303

 
5,568

 
199

 
1,712

 
1,864

Total
 
$
8,176,782

 
$
69,205

 
$
12,848

 
$
14,345

 
$
2,360

 
$
56,357

 
$
64,735

 
 
 
Recorded Investment
of Loans
Collectively Measured
for Contingency
Provision
 
Recorded Investment
of Loans
Individually
Measured for
Specific
Impairment
 
Impaired Loans With
Recorded Allowance
 
Impaired Loans Without
Recorded Allowance
 
 
Recorded
Investment
 
Unpaid
Principal
Balance
 
Related
Allowance
 
Recorded
Investment
 
Unpaid
Principal
Balance
December 31, 2016
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
2,442,772

 
$
8,818

 
$
2,414

 
$
2,484

 
$
664

 
$
6,404

 
$
12,831

Unsecured
 
94,737

 
—

 
—

 
—

 
—

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
167,403

 
529

 
435

 
693

 
12

 
94

 
291

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
270,106

 
708

 
—

 
—

 
—

 
708

 
687

Income property
 
1,365,321

 
4,425

 
540

 
544

 
27

 
3,885

 
4,148

Owner occupied
 
1,054,564

 
5,414

 
—

 
—

 
—

 
5,414

 
8,102

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
11,542

 
14

 
14

 
102

 
1

 
—

 
—

Residential construction
 
109,293

 
336

 
—

 
—

 
—

 
336

 
336

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
103,779

 
—

 
—

 
—

 
—

 
—

 
—

Owner occupied
 
103,480

 
—

 
—

 
—

 
—

 
—

 
—

Consumer
 
319,307

 
5,215

 
4,464

 
4,558

 
57

 
751

 
833

Total
 
$
6,042,304

 
$
25,459

 
$
7,867

 
$
8,381

 
$
761

 
$
17,592

 
$
27,228


The following table provides additional information on impaired loans for the years ended December 31, 2017, 2016 and 2015:
 
 
Year Ended December 31, 2017
 
Year Ended December 31, 2016
 
Year Ended December 31, 2015
 
 
Average Recorded
Investment
Impaired Loans 
 
Interest Recognized
on
Impaired Loans
 
Average Recorded
Investment
Impaired Loans 
 
Interest Recognized
on
Impaired Loans
 
Average Recorded
Investment
Impaired Loans 
 
Interest Recognized
on
Impaired Loans
 
 
(in thousands)
Commercial business
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
20,282

 
$
60

 
$
9,368

 
$
79

 
$
7,987

 
$
84

Unsecured
 
5

 
—

 
—

 
—

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
730

 
49

 
743

 
10

 
2,848

 
47

Commercial & multifamily residential
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
2,079

 
—

 
425

 
—

 
94

 
—

Income property
 
4,314

 
51

 
2,492

 
26

 
2,913

 
36

Owner occupied
 
5,335

 
445

 
5,084

 
—

 
7,052

 
26

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
3

 
—

 
199

 
—

 
641

 
5

Residential construction
 
309

 
—

 
472

 
—

 
648

 
—

Commercial & multifamily residential
 
 
 
 
 
 
 
 
 
 
 
 
Owner occupied
 
1,620

 
203

 
—

 
—

 
—

 
—

Consumer
 
5,973

 
163

 
2,710

 
122

 
189

 
4

Total
 
$
40,650

 
$
971

 
$
21,493

 
$
237

 
$
22,372

 
$
202

The following is an analysis of loans classified as troubled debt restructurings (“TDR”) for the years ended December 31, 2017, 2016 and 2015:
 
 
Year Ended December 31, 2017
 
Year Ended December 31, 2016
 
Year Ended December 31, 2015
 
 
Number of TDR Modifications
 
Pre-Modification
Outstanding
Recorded
Investment
 
Post-Modification
Outstanding
Recorded
Investment
 
Number of TDR Modifications
 
Pre-Modification
Outstanding
Recorded
Investment
 
Post-Modification
Outstanding
Recorded
Investment
 
Number of TDR Modifications
 
Pre-Modification
Outstanding
Recorded
Investment
 
Post-Modification
Outstanding
Recorded
Investment
 
 
(dollars in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
10

 
$
5,655

 
$
5,655

 
9

 
$
2,131

 
$
2,131

 
5

 
$
3,724

 
$
3,706

Unsecured
 
1

 
26

 
26

 
—

 
—

 
—

 
—

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
3

 
583

 
583

 
3

 
203

 
203

 
1

 
30

 
30

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
1

 
687

 
687

 
—

 
—

 
—

 
—

 
—

 
—

Income property
 
1

 
1,152

 
1,152

 
—

 
—

 
—

 
—

 
—

 
—

Owner occupied
 
1

 
78

 
78

 
1

 
250

 
250

 
—

 
—

 
—

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Owner occupied
 
1

 
4,050

 
4,050

 
—

 
—

 
—

 
—

 
—

 
—

Consumer
 
42

 
5,891

 
5,891

 
41

 
5,095

 
5,093

 
1

 
54

 
54

Total
 
60

 
$
18,122

 
$
18,122

 
54

 
$
7,679

 
$
7,677

 
7

 
$
3,808

 
$
3,790


The Company’s loans classified as TDR are loans that have been modified or the borrower has been granted special concessions due to financial difficulties, that if not for the challenges of the borrower, the Company would not otherwise consider. The Company had $506 thousand of commitments to lend additional funds on loans classified as TDR as of December 31, 2017 as compared to $508 thousand of similar commitments at 2016. The TDR modifications or concessions are made to increase the likelihood that these borrowers with financial difficulties will be able to satisfy their debt obligations as amended. The concessions granted in the restructurings summarized in the table above largely consisted of maturity extensions, interest rate modifications or a combination of both. In limited circumstances, a reduction in the principal balance of the loan could also be made as a concession. Credit losses for loans classified as TDR are measured on the same basis as impaired loans. For impaired loans, an allowance is established when the collateral value less selling costs (or discounted cash flows or observable market price) of the impaired loan is lower than the recorded investment of that loan. The Company did not have any loans modified as TDR that defaulted within 12 months of being modified as TDR during the years ended December 31, 2017, 2016, and 2015.
Purchased Credit Impaired Loans (“PCI Loans”)
PCI loans are accounted for under ASC 310-30 and initially measured at fair value based on expected future cash flows over the life of the loans. Loans that have common risk characteristics are aggregated into pools. The Company re-measures contractual and expected cash flows, at the pool-level, on a quarterly basis.
Contractual cash flows are calculated based upon the loan pool terms after applying a prepayment factor. Calculation of the applied prepayment factor for contractual cash flows is the same as described below for expected cash flows.
Inputs to the determination of expected cash flows include cumulative default and prepayment data as well as loss severity and recovery lag information. Cumulative default and prepayment data are calculated via a transition matrix. The transition matrix is a matrix of probability values that specifies the probability of a loan pool transitioning into a particular delinquency state (e.g. 0-30 days past due, 31 to 60 days, etc.) given its delinquency state at the re-measurement date. Loss severity factors are based upon either actual charge-off data within the loan pools or industry averages, and recovery lags are based upon the collateral within the loan pools.
The excess of cash flows expected to be collected over the initial fair value of purchased credit impaired loans is referred to as the accretable yield and is accreted into interest income over the estimated life of the acquired loans using the effective yield method. Other adjustments to the accretable yield include changes in the estimated remaining life of the acquired loans, changes in expected cash flows and changes of indices for acquired loans with variable interest rates.
The following is an analysis of our PCI loans, net of related allowance for losses and remaining valuation discounts as of December 31, 2017 and 2016:
 
 
December 31, 2017
 
December 31, 2016
 
 
(in thousands)
Commercial business
 
$
13,753

 
$
21,606

Real estate:
 
 
 
 
One-to-four family residential
 
14,610

 
20,643

Commercial and multifamily residential
 
79,211

 
94,795

Total real estate
 
93,821

 
115,438

Real estate construction:
 
 
 
 
One-to-four family residential
 
177

 
832

Commercial and multifamily residential
 
595

 
1,726

Total real estate construction
 
772

 
2,558

Consumer
 
12,412

 
17,649

Subtotal of purchased credit impaired loans
 
120,758

 
157,251

Less:
 
 
 
 
Valuation discount resulting from acquisition accounting
 
8,088

 
11,591

Allowance for loan losses
 
6,907

 
10,515

PCI loans, net of valuation discounts and allowance for loan losses
 
$
105,763

 
$
135,145


The following table shows the changes in accretable yield for acquired loans for the years ended December 31, 2017, 2016, and 2015:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Balance at beginning of period
 
$
45,191

 
$
58,981

 
$
73,849

Accretion
 
(12,357
)
 
(16,266
)
 
(21,919
)
Disposals
 
(158
)
 
(148
)
 
(1,681
)
Reclassifications from (to) nonaccretable difference
 
(1,500
)
 
2,624

 
8,732

Balance at end of period
 
$
31,176

 
$
45,191

 
$
58,981


The Company did not acquire any loans accounted for under ASC 310-30 during 2017 or 2016.
v3.8.0.1
Allowance for Loan and Lease Losses and Unfunded Commitments and Letters of Credit
 12 Months Ended
Dec. 31, 2017
Allowance For Loan And Lease Losses And Unfunded Loan Commitments And Letters Of Credit  
Allowance for Loan and Lease Losses and Unfunded Loan Commitments and Letters of Credit
Allowance for Loan and Lease Losses and Unfunded Commitments and Letters of Credit
We record an allowance to recognize management’s estimate of credit losses incurred in the loan portfolio at each balance sheet date. We have used the same methodology for allowance calculations during the twelve month periods ended December 31, 2017 and December 31, 2016.
The following tables show a detailed analysis of the allowance for loans for the years ended December 31, 2017, 2016 and 2015:
 
 
Beginning
Balance
 
Charge-offs
 
Recoveries
 
Provision (Recovery)
 
Ending
Balance
 
Specific
Reserve
 
General
Allocation
Year Ended December 31, 2017
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
36,050

 
$
(7,524
)
 
$
4,283

 
$
(3,468
)
 
$
29,341

 
$
1,867

 
$
27,474

Unsecured
 
960

 
(89
)
 
553

 
576

 
2,000

 
3

 
1,997

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
599

 
(460
)
 
568

 
(6
)
 
701

 
103

 
598

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
1,797

 
—

 
53

 
2,415

 
4,265

 
—

 
4,265

Income property
 
7,342

 
(287
)
 
498

 
(1,881
)
 
5,672

 
185

 
5,487

Owner occupied
 
6,439

 
—

 
124

 
(1,104
)
 
5,459

 
3

 
5,456

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
316

 
(14
)
 
72

 
589

 
963

 
—

 
963

Residential construction
 
669

 
—

 
106

 
2,934

 
3,709

 
—

 
3,709

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
404

 
—

 
1

 
6,648

 
7,053

 
—

 
7,053

Owner occupied
 
1,192

 
—

 
—

 
3,221

 
4,413

 
—

 
4,413

Consumer
 
3,534

 
(1,474
)
 
1,187

 
1,916

 
5,163

 
199

 
4,964

Purchased credit impaired
 
10,515

 
(6,812
)
 
6,187

 
(2,983
)
 
6,907

 
—

 
6,907

Unallocated
 
226

 
—

 
—

 
(226
)
 
—

 
—

 
—

Total
 
$
70,043

 
$
(16,660
)
 
$
13,632

 
$
8,631

 
$
75,646

 
$
2,360

 
$
73,286

 
 
Beginning
Balance
 
Charge-offs
 
Recoveries
 
Provision (Recovery)
 
Ending
Balance
 
Specific
Reserve
 
General
Allocation
Year Ended December 31, 2016
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
32,321

 
$
(9,993
)
 
$
2,483

 
$
11,239

 
$
36,050

 
$
664

 
$
35,386

Unsecured
 
1,299

 
(75
)
 
162

 
(426
)
 
960

 
—

 
960

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
916

 
(35
)
 
171

 
(453
)
 
599

 
12

 
587

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
1,178

 
(26
)
 
2

 
643

 
1,797

 
—

 
1,797

Income property
 
6,616

 
—

 
966

 
(240
)
 
7,342

 
27

 
7,315

Owner occupied
 
5,550

 
(63
)
 
434

 
518

 
6,439

 
—

 
6,439

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
339

 
(88
)
 
57

 
8

 
316

 
1

 
315

Residential construction
 
733

 
—

 
234

 
(298
)
 
669

 
—

 
669

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
388

 
—

 
109

 
(93
)
 
404

 
—

 
404

Owner occupied
 
1,006

 
—

 
—

 
186

 
1,192

 
—

 
1,192

Consumer
 
3,531

 
(1,238
)
 
933

 
308

 
3,534

 
57

 
3,477

Purchased credit impaired
 
13,726

 
(9,944
)
 
7,004

 
(271
)
 
10,515

 
—

 
10,515

Unallocated
 
569

 
—

 
—

 
(343
)
 
226

 
—

 
226

Total
 
$
68,172

 
$
(21,462
)
 
$
12,555

 
$
10,778

 
$
70,043

 
$
761

 
$
69,282


 
 
Beginning
Balance
 
Charge-offs
 
Recoveries
 
Provision (Recovery)
 
Ending
Balance
 
Specific
Reserve
 
General
Allocation
Year ended December 31, 2015
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
25,923

 
$
(7,486
)
 
$
2,069

 
$
11,815

 
$
32,321

 
$
321

 
$
32,000

Unsecured
 
927

 
(780
)
 
267

 
885

 
1,299

 
—

 
1,299

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
2,281

 
(376
)
 
307

 
(1,296
)
 
916

 
314

 
602

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
799

 
—

 
291

 
88

 
1,178

 
—

 
1,178

Income property
 
9,159

 
(390
)
 
3,568

 
(5,721
)
 
6,616

 
—

 
6,616

Owner occupied
 
5,007

 
(115
)
 
116

 
542

 
5,550

 
—

 
5,550

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
1,197

 
—

 
103

 
(961
)
 
339

 
—

 
339

Residential construction
 
1,860

 
—

 
90

 
(1,217
)
 
733

 
3

 
730

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
622

 
—

 
8

 
(242
)
 
388

 
—

 
388

Owner occupied
 
434

 
—

 
—

 
572

 
1,006

 
—

 
1,006

Consumer
 
3,180

 
(2,066
)
 
931

 
1,486

 
3,531

 
15

 
3,516

Purchased credit impaired
 
16,336

 
(13,854
)
 
7,329

 
3,915

 
13,726

 
—

 
13,726

Unallocated
 
1,844

 
—

 
—

 
(1,275
)
 
569

 
—

 
569

Total
 
$
69,569

 
$
(25,067
)
 
$
15,079

 
$
8,591

 
$
68,172

 
$
653

 
$
67,519

Changes in the allowance for unfunded commitments and letters of credit, a component of “Other liabilities” in the Consolidated Balance Sheets, are summarized as follows:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Beginning balance
 
$
2,705

 
$
2,930

 
$
2,655

Net changes in the allowance for unfunded commitments and letters of credit
 
425

 
(225
)
 
275

Ending balance
 
$
3,130

 
$
2,705

 
$
2,930


Risk Elements
The extension of credit in the form of loans or other credit products to individuals and businesses is one of our principal business activities. Our policies and applicable laws and regulations require risk analysis as well as ongoing portfolio and credit management. We manage our credit risk through lending limit constraints, credit review, approval policies and extensive, ongoing internal monitoring. We also manage credit risk through diversification of the loan portfolio by type of loan, type of industry and type of borrower and by limiting the aggregation of debt to a single borrower.
Risk ratings are reviewed and updated whenever appropriate, with more periodic reviews as the risk and dollar value of loss on the loan increases. In the event full collection of principal and interest is not reasonably assured, the loan is appropriately downgraded and, if warranted, placed on nonaccrual status even though the loan may be current as to principal and interest payments. Additionally, we assess whether an impairment of a loan warrants specific reserves or a write-down of the loan.
Pass rated loans are generally considered to have sufficient sources of repayment in order to repay the loan in full in accordance with all terms and conditions. Special Mention rated loans have potential weaknesses that, if left uncorrected, may result in deterioration of the repayment prospects for the asset or in the Company’s credit position at some future date. Loans with a risk rating of Substandard or worse are reported as classified loans in our allowance analysis. We review these loans to assess the ability of our borrowers to service all interest and principal obligations and, as a result, the risk rating may be adjusted accordingly. Loans risk rated as Substandard reflect loans where a loss is possible if loan weaknesses are not corrected. Doubtful loans have a high probability of loss; however, the amount of loss has not yet been determined. Loss rated loans are considered uncollectable and when identified, are charged off.
The following is an analysis of the credit quality of our loan portfolio, excluding PCI loans as of December 31, 2017 and 2016:
 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2017
 
(in thousands)
Loans, excluding PCI loans
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
3,049,031

 
$
64,600

 
$
122,030

 
$
—

 
$
—

 
$
3,235,661

Unsecured
 
123,621

 
—

 
554

 
—

 
—

 
124,175

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
183,312

 
1,186

 
2,056

 
—

 
—

 
186,554

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
283,673

 
5,204

 
7,104

 
—

 
—

 
295,981

Income property
 
1,857,832

 
17,181

 
31,323

 
—

 
—

 
1,906,336

Owner occupied
 
1,546,775

 
7,380

 
45,831

 
—

 
—

 
1,599,986

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
9,882

 
—

 
25

 
—

 
—

 
9,907

Residential construction
 
187,863

 
—

 
1,828

 
—

 
—

 
189,691

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
293,028

 
—

 
—

 
—

 
—

 
293,028

Owner occupied
 
68,393

 
—

 
4,050

 
—

 
—

 
72,443

Consumer
 
323,129

 
—

 
9,096

 
—

 
—

 
332,225

Total
 
$
7,926,539

 
$
95,551

 
$
223,897

 
$
—

 
$
—

 
8,245,987

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Allowance for loan losses
 
68,739

Loans, excluding PCI loans, net
 
$
8,177,248

 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2016
 
(in thousands)
Loans, excluding PCI loans
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
2,289,307

 
$
65,846

 
$
96,437

 
$
—

 
$
—

 
$
2,451,590

Unsecured
 
93,721

 
800

 
216

 
—

 
—

 
94,737

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
164,797

 
395

 
2,740

 
—

 
—

 
167,932

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
263,195

 
3,228

 
4,391

 
—

 
—

 
270,814

Income property
 
1,341,978

 
17,902

 
9,866

 
—

 
—

 
1,369,746

Owner occupied
 
1,027,019

 
6,608

 
26,351

 
—

 
—

 
1,059,978

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
11,541

 
—

 
15

 
—

 
—

 
11,556

Residential construction
 
108,941

 
—

 
688

 
—

 
—

 
109,629

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
103,779

 
—

 
—

 
—

 
—

 
103,779

Owner occupied
 
98,948

 
88

 
4,444

 
—

 
—

 
103,480

Consumer
 
317,728

 
—

 
6,794

 
—

 
—

 
324,522

Total
 
$
5,820,954

 
$
94,867

 
$
151,942

 
$
—

 
$
—

 
6,067,763

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Allowance for loan losses
 
59,528

Loans, excluding PCI loans, net
 
$
6,008,235


The following is an analysis of the credit quality of our PCI loan portfolio as of December 31, 2017 and 2016:
 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2017
 
(in thousands)
PCI loans:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
11,918

 
$
—

 
$
723

 
$
—

 
$
—

 
$
12,641

Unsecured
 
1,045

 
—

 
67

 
—

 
—

 
1,112

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
13,817

 
—

 
793

 
—

 
—

 
14,610

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
9,460

 
349

 
—

 
—

 
—

 
9,809

Income property
 
25,981

 
—

 
35

 
—

 
—

 
26,016

Owner occupied
 
42,617

 
—

 
769

 
—

 
—

 
43,386

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
169

 
—

 
8

 
—

 
—

 
177

Residential construction
 
—

 
—

 
—

 
—

 
—

 
—

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
595

 
—

 
—

 
—

 
—

 
595

Owner occupied
 
—

 
—

 
—

 
—

 
—

 
—

Consumer
 
11,705

 
—

 
707

 
—

 
—

 
12,412

Total
 
$
117,307

 
$
349

 
$
3,102

 
$
—

 
$
—

 
120,758

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Valuation discount resulting from acquisition accounting
 
8,088

Allowance for loan losses
 
6,907

PCI loans, net
 
$
105,763

 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2016
 
(in thousands)
PCI loans:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
18,824

 
$
92

 
$
1,954

 
$
—

 
$
—

 
$
20,870

Unsecured
 
736

 
—

 
—

 
—

 
—

 
736

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
19,293

 
—

 
1,350

 
—

 
—

 
20,643

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
7,333

 
—

 
213

 
—

 
—

 
7,546

Income property
 
31,042

 
—

 
1,678

 
—

 
—

 
32,720

Owner occupied
 
53,623

 
—

 
906

 
—

 
—

 
54,529

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
744

 
—

 
88

 
—

 
—

 
832

Residential construction
 
—

 
—

 
—

 
—

 
—

 
—

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
1,217

 
—

 
—

 
—

 
—

 
1,217

Owner occupied
 
509

 
—

 
—

 
—

 
—

 
509

Consumer
 
17,202

 
—

 
447

 
—

 
—

 
17,649

Total
 
$
150,523

 
$
92

 
$
6,636

 
$
—

 
$
—

 
157,251

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Valuation discount resulting from acquisition accounting
 
11,591

Allowance for loan losses
 
10,515

PCI loans, net
 
$
135,145
v3.8.0.1
Other Real Estate Owned
 12 Months Ended
Dec. 31, 2017
Other Real Estate, Foreclosed Assets, and Repossessed Assets [Abstract]  
Other Real Estate Owned
Other Real Estate Owned
The following table sets forth activity in OREO for the period:
 
 
December 31, 2017
 
December 31, 2016
 
 
(in thousands)
Balance, beginning of period
 
$
5,998

 
$
13,738

Established through acquisitions
 
10,279

 
—

Transfers in
 
106

 
1,047

Valuation adjustments
 
(364
)
 
(860
)
Proceeds from sale of OREO property
 
(2,590
)
 
(8,158
)
Gain (loss) on sale of OREO, net
 
(131
)
 
231

Balance, end of period
 
$
13,298

 
$
5,998


At December 31, 2017, the carrying amount of foreclosed residential real estate properties held as a result of obtaining physical possession was $74 thousand and the recorded investment of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings were in process was $302 thousand.
v3.8.0.1
FDIC Loss-sharing Asset and Covered Assets
 12 Months Ended
Dec. 31, 2017
Covered Assets And FDIC Loss Sharing Asset  
Covered Assets and FDIC Loss sharing Asset
FDIC Loss-sharing Asset and Covered Assets
During the current year, we entered into an agreement with the FDIC to terminate all loss-sharing agreements ahead of their contractual maturities. These loss-sharing agreements were entered into in 2010 and 2011 in conjunction with our acquisitions of (1) Columbia River Bank in January 2010, (2) American Marine Bank in January 2010, (3) Summit Bank in May 2011 and (4) First Heritage Bank in May 2011. Under the early termination, all rights and obligations of the Company and the FDIC have been resolved and completed. The Company paid the FDIC $4.7 million as consideration for early termination. The early termination was recorded in the Company’s financial statements by removing the remaining FDIC loss-sharing asset of $3.1 million and the remaining FDIC clawback liability of $5.4 million and recording a one-time, pre-tax charge on termination of $2.4 million, recorded to “Other” noninterest expense. Prior to entering into the termination agreement, the Company had $74.0 million of non-single family covered assets and $26.4 million of single family covered assets at March 31, 2017. As a result of the termination agreement, the Company will benefit from all future recoveries, and be responsible for all future losses and expenses related to the assets previously subject to the loss-sharing agreements.
The following table shows a detailed analysis of the FDIC loss-sharing asset for the years ending December 31, 2017 and 2016:
 
 
2017
 
2016
 
 
(in thousands)
Balance at beginning of period
 
$
3,535

 
$
6,568

Adjustments not reflected in income:
 
 
 
 
Cash paid to the FDIC, net
 
184

 
705

FDIC shared recoveries, net
 
(149
)
 
(1,153
)
Termination of FDIC loss-sharing agreements
 
(3,123
)
 
—

Adjustments reflected in noninterest income (1):
 
 
 
 
Amortization, net
 
(414
)
 
(2,829
)
Loan impairment
 
40

 
301

Sale of other real estate
 
18

 
148

Valuation adjustments of other real estate
 
—

 
(22
)
Other
 
(91
)
 
(183
)
Balance at end of period
 
$
—

 
$
3,535

__________
(1) Amounts shown in the table above for adjustments reflected in noninterest income include only those adjustments recorded to the noninterest income line item “Change in FDIC loss-sharing asset” in the Consolidated Statements of Income and do not include the charge related to the termination of the FDIC loss-sharing agreements.
v3.8.0.1
Premises and Equipment
 12 Months Ended
Dec. 31, 2017
Property, Plant and Equipment [Abstract]  
Premises and Equipment
Premises and Equipment
Real and personal property and software, less accumulated depreciation and amortization, were as follows:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Land
 
$
54,510

 
$
47,438

Buildings
 
110,216

 
101,196

Leasehold improvements
 
24,184

 
19,491

Furniture and equipment
 
30,486

 
26,709

Vehicles
 
473

 
536

Computer software
 
20,384

 
18,657

Total cost
 
240,253

 
214,027

Less accumulated depreciation and amortization
 
(70,763
)
 
(63,685
)
Total
 
$
169,490

 
$
150,342


Total depreciation and amortization expense was $9.8 million, $11.8 million, and $12.3 million, for the years ended December 31, 2017, 2016, and 2015, respectively.
v3.8.0.1
Goodwill and Intangible Assets
 12 Months Ended
Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]  
Goodwill and Intangible Assets
Goodwill and Other Intangible Assets
In accordance with the Intangibles – Goodwill and Other topic of the FASB ASC, goodwill is not amortized but is reviewed for potential impairment at the reporting unit level. Management analyzes its goodwill for impairment on an annual basis and between annual tests in certain circumstances such as upon material adverse changes in legal, business, regulatory and economic factors. An impairment loss is recorded to the extent that the carrying amount of goodwill exceeds its implied fair value. The Company performed its annual impairment assessment as of July 31, 2017 and concluded that there was no impairment. As of December 31, 2017 we determined there were no events or circumstances which would more likely than not reduce the fair value of our reporting unit below its carrying amount.
The core deposit intangible (“CDI”) is evaluated for impairment if events and circumstances indicate a possible impairment. The CDI is amortized on an accelerated basis over an estimated life of 10 years.
The following table sets forth activity for goodwill and other intangible assets for the period:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Goodwill, beginning of period
 
$
382,762

 
$
382,762

 
$
382,537

Established through acquisitions and provisional period adjustments (1)
 
383,080

 
—

 
225

Total goodwill, end of period
 
765,842

 
382,762

 
382,762

Other intangible assets, net
 
 
 
 
 
 
Core deposit intangible:
 
 
 
 
 
 
Gross core deposit intangible balance, beginning of period
 
58,598

 
58,598

 
58,598

Accumulated amortization, beginning of period
 
(41,886
)
 
(35,940
)
 
(29,058
)
Core deposit intangible, net, beginning of period
 
16,712

 
22,658

 
29,540

Established through acquisition
 
46,875

 
—

 
—

CDI current period amortization
 
(6,333
)
 
(5,946
)
 
(6,882
)
Total core deposit intangible, end of period
 
57,254

 
16,712

 
22,658

Intangible assets not subject to amortization
 
919

 
919

 
919

Other intangible assets, net at end of period
 
58,173

 
17,631

 
23,577

Total goodwill and intangible assets, end of period
 
$
824,015

 
$
400,393

 
$
406,339


__________
(1) See Note 2, Business Combinations, for additional information regarding the goodwill related to the acquisition of Pacific Continental on November 1, 2017.
The following table provides the estimated future amortization expense of core deposit intangibles for the succeeding five years:
Years Ending December 31,
 
(in thousands)
2018
 
$
12,235

2019
 
10,479

2020
 
8,724

2021
 
7,264

2022
 
5,880
v3.8.0.1
Deposits
 12 Months Ended
Dec. 31, 2017
Deposits [Abstract]  
Deposits
Deposits
Year-end deposits are summarized in the following table:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Core deposits:
 
 
 
 
Demand and other noninterest-bearing
 
$
5,081,901

 
$
3,944,495

Interest-bearing demand
 
1,265,212

 
985,293

Money market
 
2,543,712

 
1,791,283

Savings
 
861,941

 
723,667

Certificates of deposit, less than $250,000
 
286,791

 
304,830

Total core deposits
 
10,039,557

 
7,749,568

Certificates of deposit, $250,000 or more
 
100,399

 
79,424

Certificates of deposit insured through CDARS®
 
25,374

 
22,039

Other brokered certificates of deposits
 
78,481

 
—

Brokered money market accounts
 
289,031

 
208,348

Subtotal
 
10,532,842

 
8,059,379

Valuation adjustment resulting from acquisition accounting
 
(757
)
 
36

Total deposits
 
$
10,532,085

 
$
8,059,415


Overdrafts of $1.6 million and $4.4 million were reclassified as loan balances at December 31, 2017 and 2016, respectively.
The following table shows the amount and maturity of time deposits:
Years Ending December 31,
 
(in thousands)
2018
 
$
338,958

2019
 
74,177

2020
 
34,727

2021
 
20,857

2022
 
12,600

Thereafter
 
9,726

Total
 
$
491,045
v3.8.0.1
Federal Home Loan Bank and Federal Reserve Bank Borrowings
 12 Months Ended
Dec. 31, 2017
Federal Home Loan Bank and Federal Reserve Bank Borrowings [Abstract]  
Federal Home Loan Bank and Federal Reserve Bank Borrowings [Text Block]
Federal Home Loan Bank and Federal Reserve Bank Borrowings
FEDERAL HOME LOAN BANK
The Company has entered into borrowing arrangements with the FHLB of Des Moines (“FHLB”) to borrow funds under a short-term floating rate fed funds overnight advance program and fixed-term loan agreements. All borrowings are secured by stock of the FHLB and a blanket pledge of qualifying loans receivable. At December 31, 2017, FHLB advances were scheduled to mature as follows:
 
 
Federal Home Loan Bank Advances
Fixed rate advances
 
 
Weighted Average Rate
 
Amount
 
 
(dollars in thousands)
Within 1 year
 
2.58
%
 
$
4,000

Over 1 through 5 years
 
3.85
%
 
2,000

Due after 10 years
 
5.37
%
 
5,000

Total
 
11,000

Valuation adjustment from acquisition accounting
 
579

Total
 
$
11,579


The maximum, average outstanding and year-end balances and average interest rates on advances from the FHLB were as follows for the years ended December 31, 2017, 2016 and 2015:
 
 
Years ended December 31,
 
 
2017
 
2016
 
2015
 
 
(dollars in thousands)
Balance at end of period
 
$
11,579

 
$
6,493

 
$
68,531

Average balance during period
 
$
79,788

 
$
79,673

 
$
70,678

Maximum month-end balance during period
 
$
317,480

 
$
250,515

 
$
242,556

Weighted average rate during period
 
1.33
%
 
0.80
%
 
0.68
%
Weighted average rate at December 31
 
4.08
%
 
5.42
%
 
0.79
%

FHLB advances are collateralized by the following:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Recorded value of blanket pledge on loans receivable
 
$
1,443,554

 
$
1,510,514

Total
 
$
1,443,554

 
$
1,510,514

FHLB borrowing capacity
 
$
1,432,554

 
$
1,502,284


FEDERAL RESERVE BANK
The Company is also eligible to borrow under the Federal Reserve Bank’s primary credit program, including the Term Auction Facility auctions. All borrowings are secured by certain pledged available for sale investment securities.
Although the Company has not had FRB borrowings in the last three years, the Company pledges securities and loans for borrowing capacity at the Federal Reserve Bank.
The following table shows amounts pledged to the Federal Reserve Bank:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Fair value of investment securities
 
$
51,172

 
$
32,795

Recorded value of pledged commercial loans
 
48,882

 
28,212

Total
 
$
100,054

 
$
61,007

Federal Reserve Bank borrowing capacity
 
$
100,054

 
$
61,007
v3.8.0.1
Securities Sold Under Agreements to Repurchase
 12 Months Ended
Dec. 31, 2017
Securities Sold under Agreements to Repurchase [Abstract]  
Securities sold under agreements to repurchase
Securities Sold Under Agreements to Repurchase
Securities Sold Under Agreements to Repurchase - Term
The Company has entered into wholesale repurchase agreements with certain brokers. At December 31, 2017 and 2016, the Company held $25.0 million in wholesale repurchase agreements with an interest rate of 1.88%. Securities available for sale with a carrying amount of $28.5 million at December 31, 2017 were pledged as collateral for the repurchase agreement borrowings. The broker holds the securities while the Company continues to receive the principal and interest payments from the securities. Upon maturity of the agreement in 2018, the pledged securities will be returned to the Company.
Securities Sold Under Agreements to Repurchase - Sweep
These sweep repurchase agreements are generally short-term agreements. These agreements are treated as financing transactions and the obligations to repurchase securities sold are reflected as a liability in the Consolidated Financial Statements. The dollar amount of securities underlying the agreements remains in the applicable asset account of the Consolidated Financial Statements. These agreements had a balance of $54.1 million and a weighted average interest rate of 0.11% at December 31, 2017. All of these repurchase agreements in existence at December 31, 2017 mature on a daily basis. Securities available for sale with a carrying amount of $66.5 million at December 31, 2017 were pledged as collateral for the sweep repurchase agreement borrowings.
v3.8.0.1
Subordinated debentures
 12 Months Ended
Dec. 31, 2017
Subordinated Borrowing [Line Items]  
Subordinated Borrowings Disclosure [Text Block]
Subordinated Debentures
On November 1, 2017, with its acquisition of Pacific Continental, the Company assumed $35.0 million in aggregate principal amount of fixed-to-floating rate subordinated debentures (the “Notes”). The Notes are callable at par on June 30, 2021, have a stated maturity of June 30, 2026 and bear interest at a fixed annual rate of 5.875% per year, from and including June 27, 2016, but excluding June 30, 2021. From and including June 30, 2021 through the maturity date or early redemption date, the interest rate will reset quarterly to an annual interest rate equal to the then-current three-month LIBOR plus 471.5 basis points.
v3.8.0.1
Junior subordinated debt
 12 Months Ended
Dec. 31, 2017
Junior subordinated debentures [Abstract]  
Junior subordinated debentures [Text Block]
Junior Subordinated Debentures
On November 1, 2017, with its acquisition of Pacific Continental, the Company assumed $14.4 million of trust preferred obligations. The Company redeemed $6.2 million of these obligations during 2017. At December 31, 2017, the remaining $8.2 million of obligations bore interest at a rate of 2.71%, paid quarterly.
v3.8.0.1
Derivatives and Balance Sheet Offsetting
 12 Months Ended
Dec. 31, 2017
General Discussion of Derivative Instruments and Hedging Activities [Abstract]  
Derivatives and Balance Sheet Offsetting
Derivatives and Balance Sheet Offsetting
The Company periodically enters into certain commercial loan interest rate swap agreements in order to provide commercial loan customers the ability to convert from variable to fixed interest rates. Under these agreements, the Company enters into a variable-rate loan agreement with a customer in addition to a swap agreement. This swap agreement effectively converts the customer’s variable rate loan into a fixed rate loan. The Company then enters into a corresponding swap agreement with a third party in order to offset its exposure on the variable and fixed components of the customer agreement. As the interest rate swap agreements with the customers and third parties are not designated as hedges under the Derivatives and Hedging topic of the FASB ASC, the instruments are marked to market in earnings. The notional amount of open interest rate swap agreements at December 31, 2017 and 2016 was $384.7 million and $309.3 million, respectively. Mark-to-market gains of $16 thousand for both 2017 and 2016 and $11 thousand for 2015 were recorded to “Other” noninterest expense.
The following table presents the fair value and balance sheet classification of derivatives not designated as hedging instruments at December 31, 2017 and 2016:
 
Asset Derivatives
 
Liability Derivatives
 
2017
 
2016
 
2017
 
2016
(in thousands)
Balance Sheet
Location
 
Fair Value
 
Balance Sheet
Location
 
Fair Value
 
Balance Sheet
Location
 
Fair Value
 
Balance Sheet
Location
 
Fair Value
Interest rate contracts
Other assets
 
$
6,707

 
Other assets
 
$
9,012

 
Other liabilities
 
$
6,714

 
Other liabilities
 
$
9,036

The Company is party to interest rate swap agreements and repurchase agreements that are subject to enforceable master netting arrangements or similar agreements. Under these agreements, the Company may have the right to net settle multiple contracts with the same counterparty. The following tables show the gross interest rate swap agreements and repurchase agreements in the Consolidated Balance Sheets and the respective collateral received or pledged in the form of other financial instruments, which are generally marketable securities. The collateral amounts in these tables are limited to the outstanding balances of the related asset or liability. Therefore, instances of overcollateralization are not shown.
 
Gross Amounts of Recognized Assets/Liabilities
 
Gross Amounts Offset in the Consolidated Balance Sheets
 
Net Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheets
 
Gross Amounts Not Offset in the Consolidated Balance Sheets
 
 
 
 
Collateral Posted
 
Net Amount
December 31, 2017
(in thousands)
Assets
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
6,707

 
$
—

 
$
6,707

 
$
—

 
$
6,707

Liabilities
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
6,714

 
$
—

 
$
6,714

 
$
(6,714
)
 
$
—

Repurchase agreements
$
79,059

 
$
—

 
$
79,059

 
$
(79,059
)
 
$
—

 
 
 
 
 
 
 
 
 
 
December 31, 2016
 
 
 
 
 
 
 
 
 
Assets
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
9,012

 
$
—

 
$
9,012

 
$
—

 
$
9,012

Liabilities
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
9,036

 
$
—

 
$
9,036

 
$
(9,036
)
 
$
—

Repurchase agreements
$
80,822

 
$
—

 
$
80,822

 
$
(80,822
)
 
$
—


The following table presents the class of collateral pledged for repurchase agreements as well as the remaining contractual maturity of the repurchase agreements:
 
 
Remaining contractual maturity of the agreements
 
 
Overnight and continuous
 
Up to 30 days
 
30 - 90 days
 
Greater than 90 days
 
Total
December 31, 2017
 
(in thousands)
Class of collateral pledged for repurchase agreements
 
 
 
 
 
 
 
 
 
 
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
54,059

 
$
—

 
$
25,000

 
$
—

 
$
79,059

Gross amount of recognized liabilities for repurchase agreements
 
79,059

Amounts related to agreements not included in offsetting disclosure
 
$
—


The collateral utilized for the Company’s repurchase agreements is subject to market fluctuations as well as prepayments of principal. The Company monitors the risk of the fair value of its pledged collateral falling below acceptable amounts based on the type of the underlying repurchase agreement. The pledged collateral related to the Company’s $25.0 million term wholesale repurchase agreement, which matures in 2018, is monitored on a monthly basis and additional collateral is pledged when necessary. The pledged collateral related to the Company’s $54.1 million sweep repurchase agreements, which mature on an overnight basis, is monitored on a daily basis as the underlying sweep accounts can have frequent transaction activity and the amount of pledged collateral is adjusted as necessary.
v3.8.0.1
Employee Benefit Plans
 12 Months Ended
Dec. 31, 2017
Retirement Benefits [Abstract]  
Employee Benefit Plans
Employee Benefit Plans
401(k) Plan
The Company maintains defined contribution and profit sharing plans in conformity with the provisions of section 401(k) of the Internal Revenue Code. The Columbia Bank 401(k) and Profit Sharing Plan (the “401(k) Plan”), permits Columbia Bank employees who are at least 18 years of age to contribute up to 75% of their eligible compensation to the 401(k) Plan starting on the first day of the month following their hire date. On a per pay period basis the Company is required to match 50% of employee contributions up to 3% of each employee’s eligible compensation. The Company contributed $2.7 million during 2017, $2.4 million during 2016, and $2.3 million during 2015, in matching funds to the 401(k) Plan. Additionally, as determined annually by the board of directors of the Company, the 401(k) Plan provides for a non-matching discretionary profit sharing contribution. The Company’s discretionary profit sharing contributions were $5.7 million during 2017, $5.1 million during 2016 and $5.2 million during 2015.
Employee Stock Purchase Plan
The Company maintains an “Employee Stock Purchase Plan” (the “ESP Plan”) in which substantially all employees of the Company are eligible to participate. The ESP Plan provides participants the opportunity to purchase common stock of the Company at a discounted price. Under the ESP Plan, participants can purchase common stock of the Company for 90% of the lowest price on either the first or last day in each of two six month look-back periods. The look-back periods are January 1st through June 30th and July 1st through December 31st of each calendar year. The 10% discount is recognized by the Company as compensation expense and does not have a material impact on net income or earnings per common share. Participants of the ESP Plan purchased 38,387 shares for $1.5 million in 2017, 50,116 shares for $1.8 million in 2016 and 42,134 shares for $1.2 million in 2015. At December 31, 2017 there were 411,107 shares available for purchase under the ESP Plan.
Supplemental Compensation Plan
The Company maintains supplemental compensation arrangements (“Unit Plans”) to provide benefits for certain employees. The Unit Plans generally vest over a 10 year period and provide a fixed annual benefit over the subsequent 10 year period. At December 31, 2017 and 2016, the liability associated with these plans was $4.6 million and $4.8 million, respectively. Expense associated with these plans for the years ended December 31, 2017, 2016 and 2015 was $452 thousand, $467 thousand and $859 thousand, respectively.
Supplemental Executive Retirement Plan
The Company maintains a supplemental executive retirement plan (the “SERP”), a nonqualified deferred compensation plan that provides retirement benefits to certain highly compensated executives. The SERP is unsecured and unfunded and there are no program assets. The SERP projected benefit obligation, which represents the vested net present value of future payments to individuals under the plan is accrued over the estimated remaining term of employment of the participants and has been determined by actuarial valuation using “RP-2014 Adjusted to 2006 Total Dataset Mortality Table with Scale MP-2017 projected to 2028” for the mortality assumptions and discount rate of 3.80% for 2017 and 4.09% for 2016. Additional assumptions and features of the plan are a normal retirement age of 65 and a 2% annual cost of living benefit adjustment. The projected benefit obligation is included in “Other liabilities” on the Consolidated Balance Sheets.
The following table reconciles the accumulated liability for the projected benefit obligation:
 
 
December 31,
2017
 
2016
 
 
(in thousands)
Balance at beginning of year
 
$
26,263

 
$
25,544

Change in actuarial loss (gain)
 
(6,453
)
 
62

Plan amendments
 
148

 
—

Benefit expense
 
1,600

 
2,201

Benefit payments
 
(1,005
)
 
(1,544
)
Balance at end of year
 
$
20,553

 
$
26,263


The benefits expected to be paid in conjunction with the SERP are presented in the following table:
Years Ending December 31,
 
(in thousands)
2018
 
$
936

2019
 
963

2020
 
1,971

2021
 
2,095

2022
 
1,135

2023 through 2027
 
7,563

Total
 
$
14,663
v3.8.0.1
Commitments and Contingent Liabilities
 12 Months Ended
Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingent Liabilities
Commitments and Contingent Liabilities
Lease Commitments: The Company’s lease commitments consist primarily of leased locations under various non-cancellable operating leases that expire between 2018 and 2043. The majority of the leases contain renewal options and provisions for increases in rental rates based on an agreed upon index or predetermined escalation schedule. As of December 31, 2017, minimum future rental payments, exclusive of taxes and other charges, of these leases were:
Years Ending December 31,
 
(in thousands)
2018
 
$
10,994

2019
 
10,458

2020
 
8,730

2021
 
7,104

2022
 
6,303

Thereafter
 
14,482

Total minimum payments
 
$
58,071


Total rental expense on buildings and equipment, net of rental income of $791 thousand, $992 thousand and $1.1 million, was $7.9 million, $8.7 million and $7.4 million, for the years ended December 31, 2017, 2016 and 2015, respectively.
Sale-leaseback transactions: On August 11, 2017, the Company sold one of its Idaho facilities and leased back the portion of the facility utilized for branch operations. The lease term is through August 2027, with monthly payments of approximately $26 thousand. The resulting gain on sale of $509 thousand was deferred in accordance with the Leases topic of the FASB ASC and is being amortized over the life of the respective lease. At December 31, 2017, the deferred gain was $490 thousand and is included in “Other liabilities” on the Consolidated Balance Sheets.
On August 24, 2016, the Company sold one of its Washington facilities and leased back the portion of the facility utilized for branch operations. The lease term is through August 2026, with monthly payments of approximately $12 thousand. The resulting gain on sale of $742 thousand was deferred in accordance with the Leases topic of the FASB ASC and is being amortized over the life of the respective lease. At December 31, 2017, the deferred gain was $644 thousand and is included in “Other liabilities” on the Consolidated Balance Sheets.
Financial Instruments with Off-Balance Sheet Risk: In the normal course of business, the Company makes loan commitments (typically unfunded loans and unused lines of credit) and issues standby letters of credit to accommodate the financial needs of its customers.
Standby letters of credit commit the Company to make payments on behalf of customers under specified conditions. Historically, no significant losses have been incurred by the Company under standby letters of credit. Both arrangements have credit risk essentially the same as that involved in extending loans to customers and are subject to the Company’s normal credit policies, including collateral requirements, where appropriate. At December 31, 2017 and 2016, the Company’s loan commitments amounted to $2.62 billion and $2.17 billion, respectively. Standby letters of credit were $51.3 million and $49.7 million at December 31, 2017 and 2016, respectively. In addition, commitments under commercial letters of credit used to facilitate customers’ trade transactions and other off-balance sheet liabilities amounted to $159 thousand and $3.4 million at December 31, 2017 and 2016, respectively.
Legal Proceedings: The Company and its subsidiaries are from time to time defendants in and are threatened with various legal proceedings arising from their regular business activities. Management, after consulting with legal counsel, is of the opinion that the ultimate liability, if any, resulting from these pending or threatened actions and proceedings will not have a material effect on the financial statements of the Company.
v3.8.0.1
Shareholders' Equity
 12 Months Ended
Dec. 31, 2017
Stockholders' Equity Note [Abstract]  
Shareholders' Equity
Shareholders’ Equity
Preferred Stock. In conjunction with the 2013 acquisition of West Coast Bancorp, the Company issued 8,782 shares of mandatorily convertible cumulative participating preferred stock, Series B (“Series B Preferred Stock”). On January 12, 2017, all outstanding shares of Series B Preferred Stock were converted to Company common stock.
Dividends. On January 26, 2017, the Company declared a quarterly cash dividend of $0.22 per common share payable on February 22, 2017 to shareholders of record as of the close of business on February 8, 2017.
On April 27, 2017, the Company declared a quarterly cash dividend of $0.22 per common share payable on May 24, 2017 to shareholders of record at the close of business on May 10, 2017.
On July 27, 2017, the Company declared a quarterly cash dividend of $0.22 per common share payable on August 23, 2017 to shareholders of record at the close of business on August 9, 2017.
On October 19, 2017, the Company declared a quarterly cash dividend of $0.22 per common share payable on November 14, 2017 to shareholders of record at the close of business on October 31, 2017.
Subsequent to year end, on January 25, 2018, the Company declared a quarterly cash dividend of $0.22 per share payable on February 21, 2018, to shareholders of record at the close of business on February 7, 2018.
The payment of cash dividends is subject to federal regulatory requirements for capital levels and other restrictions. In addition, the cash dividends paid by Columbia Bank to the Company are subject to both federal and state regulatory requirements.
v3.8.0.1
Accumulated Other Comprehensive Income
 12 Months Ended
Dec. 31, 2017
Accumulated Other Comprehensive Income [Abstract]  
Comprehensive Income (Loss) Note [Text Block]
Accumulated Other Comprehensive Loss
The following table shows changes in accumulated other comprehensive income (loss) by component for the years ended December 31, 2017, 2016 and 2015:
 
 
Unrealized Gains and Losses on Available-for-Sale Securities (1)
 
Unrealized Gains and Losses on Pension Plan Liability (1)
 
Total (1)
Year Ended December 31, 2017
 
(in thousands)
Beginning balance
 
$
(12,704
)
 
$
(6,295
)
 
$
(18,999
)
Other comprehensive income (loss) before reclassifications
 
(3,391
)
 
4,017

 
626

Amounts reclassified from accumulated other comprehensive loss (2)
 
7

 
223

 
230

Net current-period other comprehensive income (loss)
 
(3,384
)
 
4,240

 
856

Adjustment pursuant to adoption of ASU 2018-02
 
(3,691
)
 
(391
)
 
(4,082
)
Ending balance
 
$
(19,779
)
 
$
(2,446
)
 
$
(22,225
)
Year Ended December 31, 2016
 
 
 
 
 
 
Beginning balance
 
$
386

 
$
(6,681
)
 
$
(6,295
)
Other comprehensive loss before reclassifications
 
(12,338
)
 
(39
)
 
(12,377
)
Amounts reclassified from accumulated other comprehensive loss (2)
 
(752
)
 
425

 
(327
)
Net current-period other comprehensive income (loss)
 
(13,090
)
 
386

 
(12,704
)
Ending balance
 
$
(12,704
)
 
$
(6,295
)
 
$
(18,999
)
Year Ended December 31, 2015
 
 
 
 
 
 
Beginning balance
 
$
7,462

 
$
(1,841
)
 
$
5,621

Other comprehensive loss before reclassifications
 
(6,069
)
 
(5,054
)
 
(11,123
)
Amounts reclassified from accumulated other comprehensive income (2)
 
(1,007
)
 
214

 
(793
)
Net current-period other comprehensive loss
 
(7,076
)
 
(4,840
)
 
(11,916
)
Ending balance
 
$
386

 
$
(6,681
)
 
$
(6,295
)
__________
(1) All amounts are net of tax. Amounts in parenthesis indicate debits.
(2) See following table for details about these reclassifications.
In December 2017, the Company made an election to reclassify income tax effects related to the Tax Cuts and Jobs Act of $4.1 million from accumulated other comprehensive income to retained earnings. The Company uses the portfolio approach to account for the tax consequences of amounts reported in OCI.

The following table shows details regarding the reclassifications from accumulated other comprehensive income for the years ended December 31, 2017, 2016 and 2015:
 
 
Amount Reclassified from Accumulated Other Comprehensive Income
 
Affected line Item in the Consolidated Statement of Income
 
 
Years Ended
 
 
 
 
December 31, 2017
 
December 31, 2016
 
December 31, 2015
 
 
 
 
(in thousands)
 
 
Unrealized gains and losses on available-for-sale securities
 
$
(11
)
 
$
1,181

 
$
1,581

 
Investment securities gains (losses), net
 
 
(11
)
 
1,181

 
1,581

 
Total before tax
 
 
4

 
(429
)
 
(574
)
 
Income tax benefit (provision)
 
 
$
(7
)
 
$
752

 
$
1,007

 
Net of tax
 
 
 
 
 
 
 
 
 
Amortization of pension plan liability
actuarial losses
 
$
(350
)
 
$
(668
)
 
$
(336
)
 
Compensation and employee benefits
 
 
(350
)
 
(668
)
 
(336
)
 
Total before tax
 
 
127

 
243

 
122

 
Income tax benefit
 
 
$
(223
)
 
$
(425
)
 
$
(214
)
 
Net of tax
v3.8.0.1
Fair Value Accounting and Measurement
 12 Months Ended
Dec. 31, 2017
Fair Value Disclosures [Abstract]  
Fair Value Accounting and Measurement
Fair Value Accounting and Measurement
The Fair Value Measurements and Disclosures topic of the FASB ASC defines fair value, establishes a consistent framework for measuring fair value and expands disclosure requirements about fair value. We hold fixed and variable rate interest-bearing securities, investments in marketable equity securities and certain other financial instruments, which are carried at fair value. Fair value is determined based upon quoted prices when available or through the use of alternative approaches, such as matrix or model pricing, when market quotes are not readily accessible or available.
The valuation techniques are based upon observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our own market assumptions. These two types of inputs create the following fair value hierarchy:
Level 1 – Quoted prices for identical instruments in active markets that are accessible at the measurement date.
Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model derived valuations whose inputs are observable or whose significant value drivers are observable.
Level 3 – Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable.
Fair values are determined as follows:
Securities at fair value are priced using a combination of market activity, industry recognized information sources, yield curves, discounted cash flow models and other factors. These fair value calculations are considered a Level 2 input method under the provisions of the Fair Value Measurements and Disclosures topic of the FASB ASC for all securities other than U.S. Treasury Notes and other securities, which are considered a Level 1 input method.
Interest rate contract positions are valued in models, which use as their basis, readily observable market parameters and are classified within Level 2 of the valuation hierarchy.
The following table sets forth the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis at December 31, 2017 and 2016 by level within the fair value hierarchy. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement:
 
 
Fair value  at
December 31, 2017
 
Fair Value Measurements at Reporting Date Using
 
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
Securities available for sale
 
 
 
 
 
 
 
 
U.S. government agency and sponsored enterprise mortgage-back securities and collateralized mortgage obligations
 
$
1,726,725

 
$
—

 
$
1,726,725

 
$
—

State and municipal securities
 
596,004

 
—

 
596,004

 
—

U.S. government agency and government-sponsored enterprise securities
 
414,774

 
—

 
414,774

 
—

U.S. government securities
 
248

 
248

 
—

 
—

Other securities
 
5,080

 
5,080

 
—

 
—

Total securities available for sale
 
$
2,742,831

 
$
5,328

 
$
2,737,503

 
$
—

Other assets (Interest rate contracts)
 
$
6,707

 
$
—

 
$
6,707

 
$
—

Liabilities
 
 
 
 
 
 
 
 
Other liabilities (Interest rate contracts)
 
$
6,714

 
$
—

 
$
6,714

 
$
—

 
 
Fair value  at
December 31, 2016
 
Fair Value Measurements at Reporting Date Using
 
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
Securities available for sale
 
 
 
 
 
 
 
 
U.S. government agency and sponsored enterprise mortgage-back securities and collateralized mortgage obligations
 
$
1,465,732

 
$
—

 
$
1,465,732

 
$
—

State and municipal debt securities
 
475,060

 
—

 
475,060

 
—

U.S. government agency and government-sponsored enterprise securities
 
331,902

 
—

 
331,902

 
—

U.S. government securities
 
800

 
800

 
—

 
—

Other securities
 
5,083

 
—

 
5,083

 
—

Total securities available for sale
 
$
2,278,577

 
$
800

 
$
2,277,777

 
$
—

Other assets (Interest rate contracts)
 
$
9,012

 
$
—

 
$
9,012

 
$
—

Liabilities
 
 
 
 
 
 
 
 
Other liabilities (Interest rate contracts)
 
$
9,036

 
$
—

 
$
9,036

 
$
—


During the year ended December 31, 2017 there was a transfer of $5.1 million out of Level 2 of the valuation hierarchy and a corresponding transfer into Level 1 of the valuation hierarchy related to the Company’s other securities. The Company determined that the other securities were traded in active markets. The Company recognizes transfers between levels of the valuation hierarchy based on the valuation level at the end of the reporting period. There were no transfers between Level 1 and Level 2 of the valuation hierarchy during the year ended December 31, 2016.
Nonrecurring Measurements
Certain assets and liabilities are measured at fair value on a nonrecurring basis after initial recognition such as loans measured for impairment and OREO. The following methods were used to estimate the fair value of each such class of financial instrument:
Impaired loans—A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due (both interest and principal) according to the contractual terms of the loan agreement. Impaired loans are measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate, a loan’s observable market price, or the fair market value of the collateral less estimated costs to sell if the loan is a collateral-dependent loan. Generally, the Company utilizes the fair market value of the collateral to measure impairment. The impairment evaluations are performed in conjunction with the ALLL process on a quarterly basis by officers in the Special Credits group, which reports to the Chief Credit Officer. The Real Estate Appraisal Services Department (“REASD”), which also reports to the Chief Credit Officer, is responsible for obtaining appraisals from third-parties or performing internal evaluations. If an appraisal is obtained from a third-party, the REASD reviews the appraisal to evaluate the adequacy of the appraisal report, including its scope, methods, accuracy, and reasonableness.
Other real estate owned —OREO is real property that the Bank has taken ownership of in partial or full satisfaction of a loan or loans. OREO is generally measured based on the property’s fair market value as indicated by an appraisal or a letter of intent to purchase. OREO is initially recorded at the fair value less estimated costs to sell. This amount becomes the property’s new basis. Any fair value adjustments based on the property’s fair value less estimated costs to sell at the date of acquisition are charged to the ALLL, or in the event of a write-up without previous losses charged to the ALLL, a credit to earnings is recorded. Management periodically reviews OREO in an effort to ensure the property is recorded at its fair value, net of estimated costs to sell. Any fair value adjustments subsequent to acquisition are charged or credited to earnings. The initial and subsequent evaluations are performed by officers in the Special Credits group, which reports to the Chief Credit Officer. The REASD obtains appraisals from third-parties for OREO and performs internal evaluations. If an appraisal is obtained from a third-party, the REASD reviews the appraisal to evaluate the adequacy of the appraisal report, including its scope, methods, accuracy, and reasonableness.
The following table sets forth the Company’s assets that were measured using fair value estimates on a nonrecurring basis during the years ended December 31, 2017 and 2016:
 
 
Fair value  at
December 31, 2017
 
Fair Value Measurements at Reporting Date Using
 
Losses During the Year Ended
December 31, 2017
 
 
Level 1
 
Level 2
 
Level 3
 
 
 
(in thousands)
Impaired loans
 
$
6,577

 
$
—

 
$
—

 
$
6,577

 
$
2,507

OREO
 
1,423

 
—

 
—

 
1,423

 
239

 
 
$
8,000

 
$
—

 
$
—

 
$
8,000

 
$
2,746

 
 
Fair value  at
December 31, 2016
 
Fair Value Measurements at Reporting Date Using
 
Losses During the Year Ended
December 31, 2016
 
 
Level 1
 
Level 2
 
Level 3
 
 
 
(in thousands)
Impaired loans
 
$
3,787

 
$
—

 
$
—

 
$
3,787

 
$
5,413

OREO
 
4,388

 
—

 
—

 
4,388

 
332

 
 
$
8,175

 
$
—

 
$
—

 
$
8,175

 
$
5,745


The losses on impaired loans disclosed above represent the amount of the specific reserve and/or charge-offs during the period applicable to loans held at period end. The amount of the specific reserve is included in the “Allowance for loan and lease losses.” The losses on OREO disclosed above represent the write-downs taken at foreclosure that were charged to the allowance for loan and lease losses, as well as subsequent changes in any valuation allowances from updated appraisals that were recorded to earnings.
Quantitative information about Level 3 fair value measurements
The range and weighted-average of the significant unobservable inputs used to fair value our Level 3 nonrecurring assets during 2017 and 2016, along with the valuation techniques used, are shown in the following tables:
 
 
Fair value  at
December 31, 2017
 
Valuation Technique
 
Unobservable Input
 
Range (Weighted Average) (1)
 
 
(dollars in thousands)
Impaired loans - collateral-dependent (3)
 
$
3,519

 
Fair Market Value of Collateral
 
Adjustment to Stated Value
 
N/A (2)
Impaired loans - other
 
$
3,058

 
Discounted Cash Flow
 
Discount Rate
 
3.75% - 7.75% (4.12%)
OREO
 
$
1,423

 
Fair Market Value of Collateral
 
Adjustment to Appraisal Value
 
N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of real property and a government agency guarantee.

 
 
Fair value  at
December 31, 2016
 
Valuation Technique
 
Unobservable Input
 
Range (Weighted Average) (1)
 
 
(dollars in thousands)
Impaired loans - collateral-dependent (3)
 
$
2,248

 
Fair Market Value of Collateral
 
Adjustment to Stated Value
 
N/A (2)
Impaired loans - other
 
$
1,539

 
Discounted Cash Flow
 
Discount Rate
 
4.50% - 6.50% (5.26%)
OREO
 
$
4,388

 
Fair Market Value of Collateral
 
Adjustment to Appraisal Value
 
N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of accounts receivable, inventory, equipment and real property.

Fair value of financial instruments
Because broadly traded markets do not exist for most of the Company’s financial instruments, the fair value calculations attempt to incorporate the effect of current market conditions at a specific time. These determinations are subjective in nature, involve uncertainties and matters of significant judgment and do not include tax ramifications; therefore, the results cannot be determined with precision, substantiated by comparison to independent markets and may not be realized in an actual sale or immediate settlement of the instruments. There may be inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results. For all of these reasons, the aggregation of the fair value calculations presented herein do not represent, and should not be construed to represent, the underlying value of the Company.
The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value:
Cash and due from banks and interest-earning deposits with banks—The fair value of financial instruments that are short-term or reprice frequently and that have little or no risk are considered to have a fair value that approximates carrying value (Level 1).
Securities available for sale—Securities at fair value, other than U.S. Treasury Notes, are priced using a combination of market activity, industry recognized information sources, yield curves, discounted cash flow models and other factors (Level 2). U.S. Treasury Notes and other securities are priced using quotes in active markets (Level 1).
Federal Home Loan Bank stock—The fair value is based upon the par value of the stock which equates to its carrying value (Level 2).
Loans held for sale—The carrying amount of loans held for sale approximates their fair values due to the short period of time between the origination and sales dates (Level 2).
Loans—Loans are not recorded at fair value on a recurring basis. Nonrecurring fair value adjustments are periodically recorded on impaired loans that are measured for impairment based on the fair value of collateral. For most performing loans, fair value is estimated using expected duration and lending rates that would have been offered on December 31, 2017 or 2016 for loans which mirror the attributes of the loans with similar rate structures and average maturities. The fair values resulting from these calculations are reduced by an amount representing the change in estimated fair value attributable to changes in borrowers’ credit quality since the loans were originated. For nonperforming loans, fair value is estimated by applying a valuation discount based upon loan sales data from the FDIC. For PCI loans, fair value is estimated by discounting the expected future cash flows using a lending rate that would have been offered on December 31, 2017 (Level 3).
FDIC loss-sharing asset —The fair value of the FDIC loss-sharing asset was estimated based on discounting the expected future cash flows using an estimated market rate (Level 3).
Interest rate contracts—Interest rate contracts are valued in discounted cash flow models, which use readily observable market parameters as their basis (Level 2).
Deposits—For deposits with no contractual maturity, the fair value is equal to the carrying value (Level 1). The fair value of fixed maturity deposits is based on discounted cash flows using the difference between the deposit rate and current market rates for deposits of similar remaining maturities (Level 2).
FHLB advances—The fair value of FHLB advances is estimated based on discounting the future cash flows using the market rate currently offered (Level 2).
Repurchase agreements—The fair value of term repurchase agreements is estimated based on discounting the future cash flows using the market rate currently offered. The carrying amount of sweep repurchase agreements approximates their fair values due to the short period of time between repricing dates (Level 2).
Subordinated debentures—The fair value of subordinated debentures is estimated using the quoted prices for similar or identical instruments in markets that are not active (Level 2).
Junior subordinated debentures—The fair value is estimated as the carrying value as these obligations are redeemable and a market participant would expect redemption in the near-term. Subsequent to year-end, on January 7, 2018, the Company redeemed these obligations at their carrying amount (Level 2).
Other financial instruments—The majority of our commitments to extend credit and standby letters of credit carry current market interest rates if converted to loans, as such, carrying value is assumed to equal fair value.
The following tables summarize carrying amounts and estimated fair values of selected financial instruments for the periods indicated:
 
 
December 31,
2017
 
 
Carrying
Amount
 
Fair
Value
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
 
 
Cash and due from banks
 
$
244,615

 
$
244,615

 
$
244,615

 
$
—

 
$
—

Interest-earning deposits with banks
 
97,918

 
97,918

 
97,918

 
—

 
—

Securities available for sale
 
2,742,831

 
2,742,831

 
5,328

 
2,737,503

 
—

FHLB stock
 
10,440

 
10,440

 
—

 
10,440

 
—

Loans held for sale
 
5,766

 
5,766

 
—

 
5,766

 
—

Loans
 
8,283,011

 
8,055,817

 
—

 
—

 
8,055,817

Interest rate contracts
 
6,707

 
6,707

 
—

 
6,707

 
—

Liabilities
 
 
 
 
 
 
 
 
 
 
Deposits
 
$
10,532,085

 
$
10,524,135

 
$
10,041,040

 
$
483,095

 
$
—

FHLB advances
 
11,579

 
12,281

 
—

 
12,281

 
—

Repurchase agreements
 
79,059

 
79,070

 
—

 
79,070

 
—

Subordinated debentures
 
35,647

 
35,895

 
—

 
35,895

 
—

Junior subordinated debentures
 
8,248

 
8,248

 
—

 
8,248

 
—

Interest rate contracts
 
6,714

 
6,714

 
—

 
6,714

 
—


 
 
December 31,
2016
 
 
Carrying
Amount
 
Fair
Value
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
 
 
Cash and due from banks
 
$
193,038

 
$
193,038

 
$
193,038

 
$
—

 
$
—

Interest-earning deposits with banks
 
31,200

 
31,200

 
31,200

 
—

 
—

Securities available for sale
 
2,278,577

 
2,278,577

 
800

 
2,277,777

 
—

FHLB stock
 
10,240

 
10,240

 
—

 
10,240

 
—

Loans held for sale
 
5,846

 
5,846

 
—

 
5,846

 
—

Loans
 
6,143,380

 
6,040,439

 
—

 
—

 
6,040,439

FDIC loss-sharing asset
 
3,535

 
867

 
—

 
—

 
867

Interest rate contracts
 
9,012

 
9,012

 
—

 
9,012

 
—

Liabilities
 
 
 
 
 
 
 
 
 
 
Deposits
 
$
8,059,415

 
$
8,055,168

 
$
7,653,122

 
$
402,046

 
$
—

FHLB advances
 
6,493

 
7,070

 
—

 
7,070

 
—

Repurchase agreements
 
80,822

 
81,131

 
—

 
81,131

 
—

Interest rate contracts
 
9,036

 
9,036

 
—

 
9,036

 
—
v3.8.0.1
Earnings Per Common Share
 12 Months Ended
Dec. 31, 2017
Earnings Per Share [Abstract]  
Earnings Per Common Share
Earnings per Common Share
The Company applies the two-class method of computing basic and diluted EPS. Under the two-class method, EPS is determined for each class of common stock and participating security according to dividends declared and participation rights in undistributed earnings. The Company issues restricted shares under share-based compensation plans and preferred shares which qualify as participating securities.
The following table sets forth the computation of basic and diluted earnings per share for the periods indicated:
 
 
Year Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands except per share)
Basic EPS:
 
 
 
 
 
 
Net income
 
$
112,828

 
$
104,866

 
$
98,827

Less: Earnings allocated to participating securities
 
 
 
 
 
 
Preferred shares
 
3

 
185

 
175

Nonvested restricted shares
 
1,501

 
1,371

 
1,075

Earnings allocated to common shareholders
 
$
111,324

 
$
103,310

 
$
97,577

Weighted average common shares outstanding
 
59,882

 
57,184

 
57,019

Basic earnings per common share
 
$
1.86

 
$
1.81

 
$
1.71

Diluted EPS:
 
 
 
 
 
 
Earnings allocated to common shareholders
 
$
111,324

 
$
103,310

 
$
97,577

Weighted average common shares outstanding
 
59,882

 
57,184

 
57,019

Dilutive effect of equity awards and warrants
 
6

 
9

 
13

Weighted average diluted common shares outstanding
 
59,888

 
57,193

 
57,032

Diluted earnings per common share
 
$
1.86

 
$
1.81

 
$
1.71

Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive
 
13

 
19

 
37
v3.8.0.1
Share-Based Payments
 12 Months Ended
Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Share-Based Payments
Share-Based Payments
At December 31, 2017, the Company had one equity compensation plan (the “Plan”), which is shareholder approved, that provides for the granting of share options and shares to eligible employees and directors up to 1,800,000 shares.
Share Awards: Restricted share awards provide for the immediate issuance of shares of Company common stock to the recipient, with such shares held in escrow until certain service conditions are met, generally four years of continual service. Recipients of restricted shares do not pay any cash consideration to the Company for the shares, have the right to vote all shares subject to such grant, and receive all dividends with respect to such shares, whether or not the shares have vested. The fair value of share awards is equal to the fair market value of the Company’s common stock on the date of grant.
A summary of changes in the Company’s nonvested shares and related information for the years ended December 31, 2017, 2016 and 2015 is presented below:
Nonvested Shares
 
Shares
 
Weighted
Average
Grant-Date
Fair Value
Nonvested at January 1, 2015
 
519,785

 
$
23.03

Granted
 
306,007

 
$
28.57

Vested
 
(131,775
)
 
$
21.55

Forfeited
 
(28,315
)
 
$
24.79

Nonvested at December 31, 2015
 
665,702

 
$
25.80

Granted
 
335,593

 
$
28.40

Vested
 
(153,235
)
 
$
23.80

Forfeited
 
(29,305
)
 
$
27.13

Nonvested at December 31, 2016
 
818,755

 
$
25.81

Granted
 
337,384

 
$
38.51

Vested
 
(253,509
)
 
$
25.67

Forfeited
 
(96,924
)
 
$
28.97

Nonvested at December 31, 2017
 
805,706

 
$
25.89


As of December 31, 2017, there was $18.6 million of total unrecognized compensation cost related to nonvested share-based compensation arrangements granted under the Plan. That cost is expected to be recognized over a weighted average period of 2.5 years. The total fair value, as measured on the date of vesting, of shares vested during the years ended December 31, 2017, 2016, and 2015 was $6.5 million, $3.6 million, and $2.8 million, respectively.
Share Options: Option awards are generally granted with an exercise price equal to the market price of the Company’s stock at the date of grant; those option awards generally vest based on three years of continual service and are exercisable for a five-year period after vesting. Option awards granted have a 10-year maximum term.
The fair value of each option award is estimated on the date of grant using the Black-Scholes option valuation model. The fair value of all options is amortized on a straight-line basis over the requisite service periods, which are generally the vesting periods. The expected life of options granted represents the period of time that they are expected to be outstanding. The expected life is determined based on historical experience with similar awards, giving consideration to the contractual terms and vesting schedules. Expected volatilities of our common stock are estimated at the date of grant based on the historical volatility of the stock. The volatility factor is based on historical stock prices over the most recent period commensurate with the estimated expected life of the award. The risk-free interest rate is based on the U.S. Treasury curve in effect at the time of the award. The expected dividend yield is based on dividend trends and the market value of the Company’s stock price at the time of the award.
A summary of option activity under the Plan as of December 31, 2017, and changes during the year then ended is presented below:
Options
 
Shares
 
Weighted
Average
Exercise
Price
 
Weighted
Average
Remaining
Contractual
Term
 
Aggregate
Intrinsic
Value
($000)
Balance at December 31, 2016
 
23,429

 
$
45.98

 
 
 
 
Forfeited
 
(577
)
 
$
54.70

 
 
 
 
Expired
 
(2,284
)
 
$
135.97

 
 
 
 
Exercised
 
(2,242
)
 
$
10.05

 
 
 
 
Balance at December 31, 2017
 
18,326

 
$
38.88

 
0.7
 
$
214

Vested or expected to vest at December 31, 2017
 
18,326

 
$
38.88

 
0.7
 
$
214

Total Exercisable at December 31, 2017
 
18,326

 
$
38.88

 
0.7
 
$
214


The total intrinsic value of options exercised during the years ended December 31, 2017, 2016, and 2015 was $67 thousand, $232 thousand, and $85 thousand, respectively. There were no options granted during the years ended December 31, 2017, 2016, and 2015. There were no options that vested during the years ended December 2017, 2016, and 2015.
As of December 31, 2017, outstanding stock options consist of the following:
Ranges of
Exercise Prices
 
Number of
Option
Shares
 
Weighted Average
Remaining
Contractual Life
 
Weighted Average
Exercise Price of
Option Shares
 
Number of
Exercisable
Option Shares
 
Weighted Average
Exercise Price of
Exercisable Option
Shares
$0.00 - $9.99
 
6,393

 
1.3
 
$
9.91

 
6,393

 
$
9.91

$40.00 - $49.99
 
349

 
0.5
 
$
44.49

 
349

 
$
44.49

$50.00 - $136.93
 
11,584

 
0.3
 
$
54.70

 
11,584

 
$
54.70

 
 
18,326

 
0.7
 
$
38.88

 
18,326

 
$
38.88


It is the Company’s policy to issue new shares for share option exercises and share awards. The Company expenses awards of share options and shares on a straight-line basis over the related vesting term of the award. For the years ended December 31, 2017, 2016 and 2015, the Company recognized pre-tax share-based compensation expense of $7.7 million, $5.0 million and $4.1 million, respectively.
v3.8.0.1
Income Tax
 12 Months Ended
Dec. 31, 2017
Income Tax Disclosure [Abstract]  
Income Tax
Income Tax
The components of income tax expense are as follows:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Current tax expense
 
$
42,724

 
$
43,069

 
$
36,426

Deferred tax expense
 
22,431

 
1,846

 
6,367

Total
 
$
65,155

 
$
44,915

 
$
42,793


Significant components of the Company’s deferred tax assets and liabilities are as follows:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Deferred tax assets:
 
 
 
 
Allowance for loan and lease losses
 
$
18,315

 
$
26,638

Deferred compensation
 
9,539

 
16,232

Stock options and restricted stock
 
1,438

 
1,922

OREO
 
521

 
111

Nonaccrual interest
 
163

 
320

Purchase accounting
 
—

 
2,613

Unrealized loss on investment securities
 
5,992

 
7,492

Net operating losses and credit carryforwards
 
7,259

 
8,597

Depreciation
 
—

 
1,059

Other
 
985

 
851

Total deferred tax assets
 
44,212

 
65,835

Deferred tax liabilities:
 
 
 
 
Asset purchase tax basis difference
 
(5,709
)
 
(9,037
)
FHLB stock dividends
 
(782
)
 
(1,232
)
Deferred loan fees
 
(4,505
)
 
(5,126
)
Purchase accounting
 
(9,088
)
 
—

Depreciation
 
(1,581
)
 
—

Other
 
(2,036
)
 
(155
)
Total deferred tax liabilities
 
(23,701
)
 
(15,550
)
Net deferred tax asset
 
$
20,511

 
$
50,285


A reconciliation of the Company’s effective income tax rate with the federal statutory tax rate is as follows:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
Amount
 
Percent
 
Amount
 
Percent
 
Amount
 
Percent
 
 
(dollars in thousands)
Income tax based on statutory rate
 
$
62,262

 
35
 %
 
$
52,424

 
35
 %
 
$
49,567

 
35
 %
Reduction resulting from:
 
 
 
 
 
 
 
 
 
 
 
 
Tax exempt instruments
 
(8,485
)
 
(5
)%
 
(7,433
)
 
(5
)%
 
(6,761
)
 
(5
)%
Life insurance proceeds
 
(3,351
)
 
(2
)%
 
(1,680
)
 
(1
)%
 
(1,554
)
 
(1
)%
Acquisition costs
 
825

 
1
 %
 
—

 
—
 %
 
—

 
—
 %
Deferred tax asset revaluation
 
12,210

 
7
 %
 
—

 
—
 %
 
—

 
—
 %
Other, net
 
1,694

 
1
 %
 
1,604

 
1
 %
 
1,541

 
1
 %
Income tax provision
 
$
65,155

 
37
 %
 
$
44,915

 
30
 %
 
$
42,793

 
30
 %

As of December 31, 2017 and 2016, we had no unrecognized tax benefits. Our policy is to recognize interest and penalties on unrecognized tax benefits in “Provision for income taxes” in the Consolidated Statements of Income. There were no amounts related to interest and penalties recognized for the years ended December 31, 2017 and 2016. As a result of recent acquisitions, the Company has net operating loss carryforwards in the federal, Idaho and Oregon jurisdictions of $24.8 million, $26.9 million and $144 thousand, respectively, which begin to expire in 2024 and federal credit carryforwards of $450 thousand. Federal credit carryforwards relate to alternative minimum taxes and have no expiration. The amount of carryforwards that may be utilized annually is limited under Sections 382 and 383 as a result of changes in control. Management believes that these carryforwards will be used in the normal course of business, and as such, has not recorded a valuation allowance.
The Company’s 2017 results included the impact of the enactment of the Tax Cuts and Jobs Act, which was signed into law on December 22, 2017. The law includes significant changes to the U.S. corporate tax system, including a Federal corporate rate reduction from 35% to 21%. In 2017, the Company applied the newly enacted corporate federal income tax rate of 21% resulting in an approximately $12.2 million increase in tax expense from the re-measurement of its net deferred tax assets. The final impact of the tax rate change may differ due to changes in assumption made by the Company or actions the Company may take as a result of tax reform.
v3.8.0.1
Regulatory Capital Requirements
 12 Months Ended
Dec. 31, 2017
Regulatory Capital Requirements [Abstract]  
Regulatory Capital Requirements
Regulatory Capital Requirements
The Company (on a consolidated basis) and its banking subsidiary are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company and its banking subsidiary’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and its banking subsidiary must meet specific capital guidelines that involve quantitative measures of assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. The capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Prompt corrective action provisions are not applicable to bank holding companies.
Basel III capital requirements became effective on January 1, 2015. The new capital requirements, among other things (i) specify that Tier 1 capital consists of “Common Equity Tier 1,” or CET1, and “Additional Tier 1 capital” instruments meeting specified requirements, (ii) define CET1 narrowly by requiring that most deductions/adjustments to regulatory capital measures be made to CET1 and not to the other components of capital and (iii) expand the scope of the deductions/adjustments to capital as compared to existing regulations. Under the requirements that are now effective, the minimum capital ratios are (i) 4.5% CET1 to risk-weighted assets, (ii) 6% Tier 1 capital to risk-weighted assets, (iii) 8% total capital to risk-weighted assets and (iv) 4% Tier 1 capital to average total assets (Tier 1 leverage). The Company and the Bank have made the one-time election to opt-out of including accumulated other comprehensive income items in regulatory capital calculations.
The New Capital Rules also require a new capital conservation buffer designed to absorb losses during periods of economic stress. The capital conservation buffer is composed entirely of CET1, on top of these minimum risk-weighted asset ratios. In addition, the New Capital Rules provide for a countercyclical capital buffer applicable only to certain covered institutions. We do not expect the countercyclical capital buffer to be applicable to us or the Bank. Banking institutions with a ratio of CET1 to risk-weighted assets above the minimum but below the capital conservation buffer (or below the combined capital conservation buffer and countercyclical capital buffer, when the latter is applied) will face constraints on dividends, equity repurchases and compensation based on the amount of the shortfall.
The implementation of the capital conservation buffer began on January 1, 2016 at the 0.625% level and will be phased in over a three-year period (increasing by 0.625% on each subsequent January 1, until it reaches 2.5% on January 1, 2019). When fully phased-in, the New Capital Rules will require us, and the Bank, to maintain such additional capital conservation buffer of 2.5% of CET1, effectively resulting in minimum ratios of (i) 7% CET1 to risk-weighted assets, (ii) 8.5% Tier 1 capital to risk-weighted assets, and (iii) 10.5% total capital to risk-weighted assets. At December 31, 2017, the capital conservation buffer for the Company and the Bank was 4.9796% and 4.8123%, respectively. As such, we believe that, as of December 31, 2017, we and the Bank would meet all capital adequacy requirements under the New Capital Rules on a fully phased-in basis as if all such requirements were then in effect.
FDIC regulations set forth the qualifications necessary for a bank to be classified as “well-capitalized,” primarily for assignment of FDIC insurance premium rates. To qualify as “well-capitalized,” banks must have a CET1 risk-adjusted capital ratio of 6.5%, a Tier I risk-adjusted capital ratio of at least 8%, a total risk-adjusted capital ratio of at least 10% and a leverage ratio of at least 5%. Failure to qualify as “well-capitalized” can negatively impact a bank’s ability to expand and to engage in certain activities.
As of December 31, 2017, the most recent notification from the Federal Deposit Insurance Corporation categorized Columbia Bank as well-capitalized under the regulatory framework for prompt corrective action. To be categorized as well- capitalized, an institution must maintain minimum CET1 risk-based, Tier 1 risk-based, total risk-based and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since the notification that management believes have changed Columbia Bank’s category.
The Company and its banking subsidiary’s actual capital amounts and ratios as of December 31, 2017 and 2016 are presented in the following table:
 
 
Actual
 
Minimum Required
For Capital
Adequacy
Purposes
 
Minimum Required
Plus Capital
Conservation Buffer
Phase-In
 
Minimum Required
Plus Capital
Conservation Buffer
Fully Phased-In
 
To Be Well
Capitalized Under
Prompt
Corrective Action
Provision
Amount
 
Ratio
 
Amount
 
Ratio
 
Amount
 
Ratio
 
Amount
 
Ratio
 
Amount
 
Ratio
 
 
(dollars in thousands)
As of December 31, 2017
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CET1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,158,252

 
11.7421
%
 
$
443,886

 
4.50
%
 
$
567,187

 
5.75
%
 
$
690,489

 
7.00
%
 
N/A

 
N/A

Columbia Bank
 
$
1,184,476

 
12.0133
%
 
$
443,687

 
4.50
%
 
$
566,933

 
5.75
%
 
$
690,180

 
7.00
%
 
$
640,881

 
6.50
%
Tier 1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,165,903

 
11.8196
%
 
$
591,848

 
6.00
%
 
$
715,149

 
7.25
%
 
$
838,451

 
8.50
%
 
N/A

 
N/A

Columbia Bank
 
$
1,184,476

 
12.0133
%
 
$
591,582

 
6.00
%
 
$
714,829

 
7.25
%
 
$
838,075

 
8.50
%
 
$
788,777

 
8.00
%
Total Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,280,326

 
12.9796
%
 
$
789,130

 
8.00
%
 
$
912,432

 
9.25
%
 
$
1,035,734

 
10.50
%
 
N/A

 
N/A

Columbia Bank
 
$
1,263,252

 
12.8123
%
 
$
788,777

 
8.00
%
 
$
912,023

 
9.25
%
 
$
1,035,269

 
10.50
%
 
$
985,971

 
10.00
%
Tier 1 Capital Leverage (to average assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,165,903

 
10.9611
%
 
$
425,469

 
4.00
%
 
$
425,469

 
4.00
%
 
$
425,469

 
4.00
%
 
N/A

 
N/A

Columbia Bank
 
$
1,184,476

 
10.8186
%
 
$
437,939

 
4.00
%
 
$
437,939

 
4.00
%
 
$
437,939

 
4.00
%
 
$
547,423

 
5.00
%
As of December 31, 2016
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CET1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
873,217

 
11.6450
%
 
$
337,439

 
4.50
%
 
$
384,306

 
5.125
%
 
$
524,906

 
7.00
%
 
N/A

 
N/A

Columbia Bank
 
$
862,381

 
11.5051
%
 
$
337,304

 
4.50
%
 
$
384,152

 
5.125
%
 
$
524,696

 
7.00
%
 
$
487,217

 
6.50
%
Tier 1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
874,688

 
11.6646
%
 
$
449,919

 
6.00
%
 
$
496,786

 
6.625
%
 
$
637,386

 
8.50
%
 
N/A

 
N/A

Columbia Bank
 
$
862,381

 
11.5051
%
 
$
449,739

 
6.00
%
 
$
496,587

 
6.625
%
 
$
637,130

 
8.50
%
 
$
599,652

 
8.00
%
Total Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
947,436

 
12.6347
%
 
$
599,892

 
8.00
%
 
$
646,759

 
8.625
%
 
$
787,359

 
10.50
%
 
N/A

 
N/A

Columbia Bank
 
$
935,129

 
12.4756
%
 
$
599,652

 
8.00
%
 
$
646,500

 
8.625
%
 
$
787,043

 
10.50
%
 
$
749,565

 
10.00
%
Tier 1 Capital Leverage (to average assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
874,688

 
9.5526
%
 
$
366,263

 
4.00
%
 
$
366,263

 
4.00
%
 
$
366,263

 
4.00
%
 
N/A

 
N/A

Columbia Bank
 
$
862,381

 
9.4275
%
 
$
365,902

 
4.00
%
 
$
365,902

 
4.00
%
 
$
365,902

 
4.00
%
 
$
457,378

 
5.00
%
v3.8.0.1
Parent Company Financial Information
 12 Months Ended
Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]  
Parent Company Financial Information
Parent Company Financial Information
Condensed Balance Sheets—Parent Company Only
 
 
December 31,
2017
 
2016 (1)
 
 
(in thousands)
Assets
 
 
 
 
Cash and due from banking subsidiary
 
$
533

 
$
1,718

Interest-earning deposits
 
8,765

 
729

Total cash and cash equivalents
 
9,298

 
2,447

Investment in banking subsidiary
 
1,971,788

 
1,238,712

Investment in other subsidiaries
 
5,157

 
4,978

Goodwill (1)
 
4,729

 
7

Other assets
 
3,426

 
5,139

Total assets
 
$
1,994,398

 
$
1,251,283

Liabilities and Shareholders’ Equity
 
 
 
 
Subordinated debentures
 
$
35,647

 
$
—

Junior subordinated debentures
 
8,248

 
—

Other liabilities
 
581

 
271

Total liabilities
 
44,476

 
271

Shareholders’ equity
 
1,949,922

 
1,251,012

Total liabilities and shareholders’ equity
 
$
1,994,398

 
$
1,251,283


_________
(1) Reclassified to conform to current period’s presentation. The reclassification was limited to adding a separate line for Goodwill, which was previously included in other assets.
Condensed Statements of Income—Parent Company Only
 
 
Years Ended December 31,
2017
 
2016
 
2015
(in thousands)
Income
 
 
 
 
 
 
Dividend from banking subsidiary
 
$
66,800

 
$
83,500

 
$
67,000

Interest-earning deposits
 
2

 
4

 
5

Other income
 
8

 
8

 
92

Total income
 
66,810

 
83,512

 
67,097

Expense
 
 
 
 
 
 
Compensation and employee benefits
 
732

 
543

 
618

Subordinated debentures interest expense
 
304

 
—

 
—

Other borrowings interest expense
 
60

 
—

 
5

Other expense
 
3,090

 
1,608

 
1,368

Total expenses
 
4,186

 
2,151

 
1,991

Income before income tax benefit and equity in undistributed earnings of subsidiaries
 
62,624

 
81,361

 
65,106

Income tax benefit
 
(548
)
 
(748
)
 
(663
)
Income before equity in undistributed earnings of subsidiaries
 
63,172

 
82,109

 
65,769

Equity in undistributed earnings of subsidiaries
 
49,656

 
22,757

 
33,058

Net income
 
$
112,828

 
$
104,866

 
$
98,827


Condensed Statements of Cash Flows—Parent Company Only
 
 
Years Ended December 31,
2017
 
2016
 
2015
(in thousands)
Operating Activities
 
 
 
 
 
 
Net income
 
$
112,828

 
$
104,866

 
$
98,827

Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
 
 
 
Equity in undistributed earnings of subsidiaries
 
(49,656
)
 
(22,757
)
 
(33,058
)
Stock-based compensation expense
 
7,745

 
5,009

 
4,090

Net changes in other assets and liabilities
 
1,672

 
(394
)
 
(3,170
)
Net cash provided by operating activities
 
72,589

 
86,724

 
66,689

Investing Activities
 
 
 
 
 
 
Net cash paid in business combinations
 
(580
)
 
—

 
—

Net cash provided by investing activities
 
(580
)
 
—

 
—

Financing Activities
 
 
 
 
 
 
Preferred stock dividends
 
—

 
(157
)
 
(137
)
Common stock dividends
 
(51,308
)
 
(88,677
)
 
(77,263
)
Repayment of junior subordinated debentures
 
(6,186
)
 
—

 
(8,248
)
Cash settlement of acquired equity awards
 
(7,345
)
 
—

 
—

Purchase and retirement of common stock
 
(2,299
)
 
(1,125
)
 
(906
)
Proceeds from exercise of stock options
 
1,980

 
1,349

 
1,258

Excess tax benefit associated with share-based compensation
 
—

 
344

 
—

Net cash used in financing activities
 
(65,158
)
 
(88,266
)
 
(85,296
)
Increase (decrease) in cash and cash equivalents
 
6,851

 
(1,542
)
 
(18,607
)
Cash and cash equivalents at beginning of year
 
2,447

 
3,989

 
22,596

Cash and cash equivalents at end of year
 
$
9,298

 
$
2,447

 
$
3,989

 
 
 
 
 
 
 
Supplemental disclosure of noncash investing and financing activities
 
 
 
 
 
 
Share-based consideration issued in business combinations
 
$
636,385

 
$
—

 
$
—
v3.8.0.1
Summary Of Quarterly Financial Information (Unaudited)
 12 Months Ended
Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]  
Summary of Quarterly Financial Information (Unaudited)
Summary of Quarterly Financial Information (Unaudited)
Quarterly financial information for the years ended December 31, 2017 and 2016 is summarized as follows:
 
 
Fourth
Quarter (1)
 
Third
Quarter (2)
 
Second
Quarter
 
First
Quarter
 
Year Ended
December 31,
 
 
(in thousands, except per share amounts)
 
 
2017
 
 
 
 
 
 
 
 
 
 
Total interest income
 
$
108,841

 
$
90,303

 
$
87,786

 
$
87,816

 
$
374,746

Total interest expense
 
2,617

 
1,374

 
1,625

 
1,141

 
6,757

Net interest income
 
106,224

 
88,929

 
86,161

 
86,675

 
367,989

Provision (recapture) for loan and lease losses
 
3,327

 
(648
)
 
3,177

 
2,775

 
8,631

Noninterest income
 
23,581

 
37,067

 
24,135

 
24,859

 
109,642

Noninterest expense
 
85,627

 
67,537

 
68,867

 
68,986

 
291,017

Income before income taxes
 
40,851

 
59,107

 
38,252

 
39,773

 
177,983

Provision for income taxes
 
25,123

 
18,338

 
11,120

 
10,574

 
65,155

Net income
 
$
15,728

 
$
40,769

 
$
27,132

 
$
29,199

 
$
112,828

Per common share (3)
 
 
 
 
 
 
 
 
 
 
Earnings (basic)
 
$
0.23

 
$
0.70

 
$
0.47

 
$
0.50

 
$
1.86

Earnings (diluted)
 
$
0.23

 
$
0.70

 
$
0.47

 
$
0.50

 
$
1.86

2016
 
 
 
 
 
 
 
 
 
 
Total interest income
 
$
86,734

 
$
86,758

 
$
83,303

 
$
81,174

 
$
337,969

Total interest expense
 
997

 
1,186

 
1,163

 
1,004

 
4,350

Net interest income
 
85,737

 
85,572

 
82,140

 
80,170

 
333,619

Provision for loan and lease losses
 
18

 
1,866

 
3,640

 
5,254

 
10,778

Noninterest income
 
22,330

 
23,166

 
21,940

 
20,646

 
88,082

Noninterest expense
 
65,014

 
67,264

 
63,790

 
65,074

 
261,142

Income before income taxes
 
43,035

 
39,608

 
36,650

 
30,488

 
149,781

Provision for income taxes
 
12,317

 
12,124

 
11,245

 
9,229

 
44,915

Net income
 
$
30,718

 
$
27,484

 
$
25,405

 
$
21,259

 
$
104,866

Per common share (3)
 
 
 
 
 
 
 
 
 
 
Earnings (basic)
 
$
0.53

 
$
0.47

 
$
0.44

 
$
0.37

 
$
1.81

Earnings (diluted)
 
$
0.53

 
$
0.47

 
$
0.44

 
$
0.37

 
$
1.81

 __________
v3.8.0.1
Subsequent Events
 12 Months Ended
Dec. 31, 2017
Subsequent Events [Abstract]  
Subsequent Events [Text Block]
Subsequent Events
On January 8, 2018, the Company redeemed the remaining $8.2 million junior subordinated debentures.
v3.8.0.1
Summary of Significant Accounting Policies (Policies)
 12 Months Ended
Dec. 31, 2017
Accounting Policies [Line Items]  
Cash and cash equivalents
Cash and cash equivalents
Cash and cash equivalents include cash and due from banks, and interest-bearing balances due from correspondent banks and the Federal Reserve Bank. Cash equivalents have a maturity of 90 days or less at the time of purchase.
Securities
Securities
Securities are classified based on management’s intention on the date of purchase. All securities are classified as available for sale and are presented at fair value. Unrealized gains or losses on securities available for sale are excluded from net income but are included as separate components of other comprehensive income, net of taxes. Purchase premiums or discounts on securities available for sale are amortized or accreted into income using the interest method over the terms of the individual securities. The Company performs a quarterly assessment to determine whether a decline in fair value below amortized cost is other-than-temporary. Amortized cost includes adjustments made to the cost of an investment for accretion, amortization, collection of cash and previous other-than temporary impairment recognized in earnings. Other-than-temporary impairment exists when it is probable that the Company will be unable to recover the entire amortized cost basis of the security.
In performing the quarterly assessment for debt securities, management considers whether or not the Company expects to recover the entire amortized cost basis of the security. In addition, management also considers whether it is more likely than not that it will not have to sell the security before recovery of its cost basis. If the Company intends to sell a security or it is more likely than not it will be required to sell a security prior to recovery of its cost basis, the entire amount of impairment is recognized in earnings. If the Company does not intend to sell the security or it is not more likely than not it will be required to sell the security prior to recovery of its cost basis, the credit loss component of impairment is recognized in earnings and impairment associated with non-credit factors, such as market liquidity, is recognized in “Other comprehensive income (loss), net of tax”. A credit loss is the difference between the cost basis of the security and the present value of cash flows expected to be collected, discounted at the security’s effective interest rate at the date of acquisition. The cost basis of an other-than-temporarily impaired security is written down by the amount of impairment recognized in earnings. The new cost basis is not adjusted for subsequent recoveries in fair value. However, the difference between the new amortized cost basis and the cash flows expected to be collected is accreted as interest income. The total other-than-temporary impairment, if any, is presented in the Consolidated Statements of Income with a reduction for the amount of other-than-temporary impairment that is recognized in “Other Comprehensive Income,” if any.
Realized gains or losses on sales of securities available for sale are recorded using the specific identification method.
Federal Home Loan Bank Stock
Federal Home Loan Bank Stock
The Company holds shares of Class B stock issued by the Federal Home Loan Bank of Des Moines (the “FHLB”), which has been designated as FHLB membership stock or FHLB activity based stock in accordance with the capital plan of the FHLB. Membership stock is stock we are required to purchase and hold as a condition of membership in the FHLB. The Company’s membership stock purchase requirement is measured as a percentage of our year-end assets, subject to a $10 million cap. Activity based stock is stock we are required to purchase and hold in order to obtain an advance or participate in FHLB mortgage programs. Class B stock may be redeemed, subject to certain limitations, on five years’ written notice to the FHLB. Our FHLB stock is carried at par value because the shares are issued, transferred, redeemed, and repurchased by the FHLB at a par value of $100. The FHLB stock is subject to recoverability testing per the Financial Services-Depository and Lending topic of the FASB Accounting Standards Codification (“ASC”).
Loans
Loans
Loans, excluding purchased credit impaired loans, are generally carried at the unpaid principal balance, net of purchase premiums, purchase discounts and net deferred loan fees. Net deferred loan fees include nonrefundable loan origination fees less direct loan origination costs. Net deferred loan fees, purchase premiums and purchase discounts are amortized into interest income using either the interest method or straight-line method over the terms of the loans, adjusted for actual prepayments. The interest method is used for all loans except revolving loans, for which the straight-line method is used. Interest income is accrued as earned. Fees related to lending activities other than the origination or purchase of loans are recognized as noninterest income during the period the related services are performed.
Nonaccrual loans—Loans are placed on nonaccrual status when a loan becomes contractually past due 90 days with respect to interest or principal unless the loan is both well secured and in the process of collection, or if full collection of interest or principal becomes uncertain. When a loan is placed on nonaccrual status, any accrued and unpaid interest receivable is reversed and the amortization of net deferred loan fees, premiums and discounts ceases. The interest payments received on nonaccrual loans are generally accounted for on the cost-recovery method whereby the interest payment is applied to the principal balances. Loans may be returned to accrual status when improvements in credit quality eliminate the doubt as to the full collectability of both interest and principal and a period of sustained performance has occurred.
Impaired loans—Loans are considered impaired when based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement or when a loan has been modified in a troubled debt restructuring. The assessment for impairment occurs when and while such loans are designated as classified per the Company’s internal risk rating system or when and while such loans are on nonaccrual. All nonaccrual loans greater than $500,000 and all troubled debt restructured loans are considered impaired and analyzed individually on a quarterly basis. Classified loans with an outstanding balance greater than $500,000 are evaluated for potential impairment on a quarterly basis.
Restructured Loans—A loan is classified as a troubled debt restructuring when a borrower is experiencing financial difficulties that lead to a restructuring of the loan, and the Company grants concessions to the borrower in the restructuring that it would not otherwise consider. These concessions may include interest rate reductions, principal forgiveness, extension of maturity date and other actions intended to minimize potential losses. Generally, a nonaccrual loan that is restructured remains on nonaccrual status for a period of six months to demonstrate that the borrower can meet the restructured terms. If the borrower’s performance under the new terms is not reasonably assured, the loan remains classified as a nonaccrual loan.
Purchased Credit Impaired Loans (“PCI Loans”)—Loans acquired with evidence of credit deterioration since origination for which it is probable that all contractually required payments will not be collected are accounted for under ASC 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality. In addition, because of the significant discounts associated with certain of the acquired loan portfolios, the Company elected to account for those certain acquired loans under ASC 310-30.
In situations where such loans have similar risk characteristics, loans are aggregated into pools to estimate cash flows. A pool is accounted for as a single asset with a single interest rate, cumulative loss rate and cash flow expectation. Expected cash flows at the acquisition date in excess of the fair value of loans are considered to be accretable yield, which is recognized as interest income over the life of the loan pool using a level yield method if the timing and amount of the future cash flows of the pool is reasonably estimable. Subsequent to the acquisition date, any increases in cash flow over those expected at purchase date in excess of fair value are recorded as interest income prospectively. Any subsequent decreases in cash flow over those expected at purchase date due to credit deterioration are recognized by recording an allowance for losses on purchased credit impaired loans. Any disposals of loans, including sales of loans, payments in full or foreclosures result in the removal of the loan from the loan pool at the carrying amount.
Unfunded loan commitments—Unfunded commitments are generally related to providing credit facilities to clients of the Bank and are not actively traded financial instruments. These unfunded commitments are disclosed as financial instruments with off-balance sheet risk in Note 18 in the Notes to Consolidated Financial Statements.
Allowance for Loan and Lease Losses
Allowance for Loan and Lease Losses
The allowance for loan and lease losses (the “allowance”) is an accounting estimate of incurred credit losses in our loan portfolio at the balance sheet date. The provision for loan and lease losses is the expense recognized in the Consolidated Statements of Income to adjust the allowance to the levels deemed appropriate by management, as measured by the Company’s credit loss estimation methodologies.
Loans Collectively Evaluated for Impairment—This measure of estimated credit losses is based upon the loss experience over a historical base period adjusted for a loss emergence period. The loss emergence period is an estimate of the period that it takes, on average, for us to identify the amount of loss incurred for a loan that has suffered a loss-causing event. Management then considers the effects of the following qualitative factors to ensure our allowance reflects the inherent losses in the loan portfolio:
•
Economic and business conditions;
•
Concentration of credit;
•
Lending management and staff;
•
Lending policies and procedures;
•
Loss and recovery trends;
•
Nature and volume of the portfolio;
•
Trends in problem loans, loan delinquencies and nonaccrual loans;
•
Quality of internal loan review; and
•
External factors.
These qualitative factors have a high degree of subjectivity and changes in any of the factors could have a significant impact on our calculation of the allowance. The qualitative adjustment by loan segment is based upon management's assessment of inherent losses within a range between the weighted historical loss factor by segment and the maximum consecutive quarterly losses in the relevant loss emergence period by segment over the historical base period.
Loan and lease losses are charged against the allowance when management believes the collectability of a loan balance is unlikely. Subsequent recoveries, if any, are credited to the allowance.
Loans Individually Evaluated for Impairment—This measure of estimated credit losses begins if, based upon current information and events, we believe it is probable that we will be unable to collect all amounts due according to the contractual terms of the loan agreement or when a loan has been modified in a troubled debt restructuring. When a loan has been identified as impaired, the amount of impairment will be measured using discounted cash flows, except when it is determined that the remaining source of repayment for the loan is the operation or liquidation of the underlying collateral. In these cases, the current fair value of the collateral, reduced by costs to sell, will be used in place of discounted cash flows. As a final alternative, the observable market price of the debt may be used to assess impairment. Predominantly, the Company uses the fair value of collateral approach based upon a reliable valuation. When the measurement of the impaired loan is less than the recorded amount of the loan, an impairment is recognized by recording a charge-off to the allowance or by designating a specific reserve.
Allowance for Unfunded Commitments and Letters of Credit
Unfunded Commitments and Letters of Credit—The allowance for unfunded commitments is maintained at a level believed by management to be sufficient to absorb estimated probable losses related to these unfunded credit facilities. The determination of the adequacy of the allowance is based on periodic evaluations of the unfunded credit facilities including an assessment of the probability of commitment usage, credit risk factors for loans outstanding to these same customers, and the terms and expiration dates of the unfunded credit facilities. The allowance for unfunded commitments is included in “Other liabilities” on the Consolidated Balance Sheets, with changes to the balance charged against noninterest expense.
Premises and Equipment
Premises and Equipment
Land, buildings, leasehold improvements and equipment are stated at cost less accumulated depreciation and amortization. Gains or losses on dispositions are reflected in current operations. Expenditures for improvements and major renewals are capitalized, and ordinary maintenance, repairs and small purchases are charged to “Occupancy” in the Consolidated Statements of Income. Depreciation and amortization are computed based on the straight-line method over the estimated useful lives of the various classes of assets. The ranges of useful lives for the principal classes of assets are as follows:
Buildings and building improvements
5 to 39 years
Leasehold improvements
Term of lease or useful life, whichever is shorter
Furniture, fixtures and equipment
3 to 7 years
Vehicles
5 years
Computer software
3 to 5 years
Software
Software
Capitalized software is stated at cost, less accumulated amortization. Amortization is computed on a straight-line basis and charged to expense over the estimated useful life of the software, which is generally three years. Capitalized software is included in “Premises and equipment, net” in the Consolidated Balance Sheets.
Other Real Estate Owned—Noncovered
Other Real Estate Owned
Other real estate owned (“OREO”) is composed of real estate acquired by the Company through either foreclosure or deed in lieu of foreclosure in satisfaction of debt. At acquisition, OREO is recorded at fair value less estimated costs to sell. Any fair value adjustments at acquisition are charged to the allowance, or in the event of a write-up without previous losses charged to the allowance, a credit to earnings is recorded. The fair value of the OREO is based upon current appraisal. Losses that result from the ongoing periodic valuation of these properties are charged to the net cost of operation of OREO in the period in which they are identified. Improvements to the OREO are capitalized and holding costs are charged to the net cost of operation of OREO as incurred.
Goodwill and Intangibles
Goodwill and Intangibles
Net assets of companies acquired in a business combination are recorded at fair value at the date of acquisition. Any excess of the purchase price over the fair value of net assets acquired, including identified intangible assets, is recognized as goodwill. Goodwill is reviewed for potential impairment annually, during the third quarter, or, more frequently, if events or circumstances indicate a potential impairment, at the reporting unit level. A reporting unit is an operating segment or one level below an operating segment for which discrete financial information is available and regularly reviewed by management. The Company consists of a single reporting unit. If the fair value of the reporting unit, including goodwill, is determined to be less than the carrying amount of the reporting unit, a further test is required to measure the amount of impairment. If an impairment loss exists, the carrying amount of goodwill is adjusted to a new cost basis. Subsequent reversal of a previously recognized goodwill impairment loss is prohibited.
Identified intangible assets are amortized on an accelerated basis over the period benefited. Intangible assets are also evaluated for impairment if events and circumstances indicate a possible impairment. Such evaluation is based on undiscounted cash flow projections. At December 31, 2017, intangible assets included in the Consolidated Balance Sheets principally consisted of core deposit intangibles with an original estimated life of 10 years.
Income Taxes
Income Taxes
The provision for income taxes includes current and deferred income tax expense on net income adjusted for temporary and permanent differences such as interest income from state and municipal securities and investments in affordable housing tax credits. Deferred tax assets and liabilities are recognized for the expected future tax consequences of existing temporary differences between the financial reporting and tax reporting basis of assets and liabilities using enacted tax laws and rates. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. On a quarterly basis, management evaluates deferred tax assets to determine if these tax benefits are expected to be realized in future periods. This determination is based on facts and circumstances, including the Company’s current and future tax outlook. To the extent a deferred tax asset is no longer considered “more likely than not” to be realized, a valuation allowance is established.
We recognize the tax benefit from uncertain tax positions only if it is more likely than not that the tax positions will be sustained on examination by the tax authorities, based on the technical merits of the position. The tax benefit is measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. We recognize interest and penalties related to unrecognized tax benefits in “Provision for income taxes” in the Consolidated Statements of Income.
Earnings per Common Share
Earnings per Common Share
The Company’s capital structure includes common shares, restricted common share awards, common share options, and, during 2015, 2016 and a portion of 2017, convertible preferred shares. Restricted common share awards participate in dividends declared on common shares at the same rate as common shares. Convertible preferred shares participated in dividends declared on common shares on an “as if converted” basis. Restricted common share awards and convertible preferred shares are considered participating securities under the Earnings per Share topic of the FASB ASC.
The Company calculates earnings per common share (“EPS”) using the two-class method. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common shareholders but does not require the presentation of basic and diluted EPS for securities other than common shares. Under the two-class method, basic EPS is computed by dividing earnings allocated to common shareholders by the weighted average number of common shares outstanding for the period. Earnings allocated to common shareholders represents net income reduced by earnings allocated to participating securities. Diluted EPS is computed in the same manner as basic earnings per share except that the denominator is increased to include the number of additional common shares that would have been outstanding if certain shares issuable upon exercise of common share options were included unless those additional shares would have been anti-dilutive. For the diluted EPS computation, the treasury stock method is applied and compared to the two-class method and whichever method results in a more dilutive impact is utilized to calculate diluted EPS.
Advertising
Advertising
Advertising costs are generally expensed as incurred.
Share-Based Payment
Share-Based Payment
The Company accounts for stock options and stock awards in accordance with the Compensation—Stock Compensation topic of the FASB ASC. Authoritative guidance requires the Company to measure the cost of employee services received in exchange for an award of equity instruments, such as stock options or stock awards, based on the fair value of the award on the grant date. This cost must be recognized in the Consolidated Statements of Income over the vesting period of the award.
The Company issues restricted common share awards which generally vest over a four or five-year period during which time the holder receives dividends and has full voting rights. Restricted stock is valued at the closing price of the Company’s stock on the date of an award.
Derivatives and Hedging Activities
Derivatives and Hedging Activities
In accordance with the Derivatives and Hedging topic of the FASB ASC, the Company recognizes derivatives as assets or liabilities on the Consolidated Balance Sheets at their fair value. The Company periodically enters into interest rate contracts with customers and offsetting contracts with third parties. As these interest rate contracts are not designated as hedges under the Derivatives and Hedging topic of the FASB ASC, the changes in fair value of these instruments are recognized immediately in earnings.
Purchased Credit Impaired Loans [Member]  
Accounting Policies [Line Items]  
Allowance for Loan and Lease Losses
Purchased Credit Impaired Loans—The Company updates its cash flow projections for purchased credit impaired loans accounted for under ASC 310-30 on a quarterly basis. Assumptions utilized in this process include projections related to probability of default, loss severity, prepayment and recovery lag. Projections related to probability of default and prepayment are calculated utilizing a loan migration analysis. The loan migration analysis is a matrix of probability that is used to estimate the probability of a loan pool transitioning into a particular delinquency state given its delinquency state at the re-measurement date. Loss severity factors are based upon either actual charge-off data within the loan pools or industry averages, and recovery lags are based upon the collateral within the loan pools.
Any decreases in expected cash flows after the acquisition date and subsequent measurement periods are recognized by recording a provision for loan losses. See “Purchased Credit Impaired Loans” for further discussion.
v3.8.0.1
Business Combinations (Tables) - Pacific Continental [Member]
 12 Months Ended
Dec. 31, 2017
Business Acquisition [Line Items]  
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]
The table below summarizes the amounts recognized as of the acquisition date for each major class of assets acquired and liabilities assumed:
 
 
November 1, 2017
 
 
(in thousands)
 
 
 
 
 
Merger consideration
 
 
 
$
637,103

Identifiable net assets acquired, at fair value
 
 
 
 
Assets acquired
 
 
 
 
Cash and cash equivalents
 
$
81,190

 
 
Investment Securities
 
449,291

 
 
Federal Home Loan Bank stock
 
7,084

 
 
Loans
 
1,873,987

 
 
Interest receivable
 
7,827

 
 
Premises and equipment
 
27,343

 
 
Other real estate owned
 
10,279

 
 
Core deposit intangible
 
46,875

 
 
Other assets
 
50,638

 
 
   Total assets acquired
 
 
 
2,554,514

Liabilities assumed
 
 
 
 
Deposits
 
(2,118,982
)
 
 
Federal Home Loan Bank advances
 
(101,127
)
 
 
Subordinated debentures
 
(35,678
)
 
 
Junior subordinated debentures
 
(14,434
)
 
 
Securities sold under agreements to repurchase
 
(1,617
)
 
 
Other liabilities
 
(28,653
)
 
 
Total liabilities assumed
 
 
 
(2,300,491
)
Total fair value of identifiable net assets, at fair value
 
 
 
254,023

Goodwill
 
 
 
$
383,080
Business Acquisition, Pro Forma Information [Table Text Block]
For illustrative purposes only, the following table presents certain unaudited pro forma information for the years ended December 31, 2017 and 2016. This unaudited estimated pro forma financial information was calculated as if Pacific Continental had been acquired as of the beginning of the year prior to the date of acquisition. This unaudited pro forma information combines the historical results of Pacific Continental with the Company’s consolidated historical results and includes certain adjustments reflecting the estimated impact of certain fair value adjustments for the respective periods. The pro forma information is not indicative of what would have occurred had the acquisition occurred as of the beginning of the year prior to the acquisition. In particular, no adjustments have been made to eliminate the impact of other-than-temporary impairment losses and losses recognized on the sale of securities that may not have been necessary had the investment securities been recorded at fair value as of the beginning of the year prior to the date of acquisition. The unaudited pro forma information does not consider any changes to the provision for credit losses resulting from recording loan assets at fair value. Additionally, Columbia expects to achieve further operating cost savings and other business synergies, including revenue growth as a result of the acquisition, which are not reflected in the pro forma amounts that follow. As a result, actual amounts would have differed from the unaudited pro forma information presented.
 
 
Unaudited Pro Forma
 
 
Years Ended December 31,
 
 
2017
 
2016
 
 
(in thousands except per share)
Total revenues (net interest income plus noninterest income)
 
$
571,944

 
$
520,419

Net income
 
$
149,859

 
$
124,550

Earnings per share - basic
 
$
2.23

 
$
1.86

Earnings per share - diluted
 
$
2.23

 
$
1.86
Business Acquisition, Integration, Restructuring and Other Related Costs [Text Block]
The following table shows the impact of the acquisition-related expenses related to the acquisition of Pacific Continental for the periods indicated to the various components of noninterest expense:
 
 
Year ended December 31,
 
 
2017
 
2016
 
 
(in thousands)
Noninterest Expense
 
 
 
 
Compensation and employee benefits
 
$
8,014

 
$
—

Occupancy
 
1,912

 
—

Advertising and promotion
 
467

 
—

Data processing
 
1,555

 
—

Legal and professional fees
 
4,618

 
291

Taxes, licenses and fees
 
10

 
—

Other
 
620

 
—

Total impact of acquisition-related costs to noninterest expense
 
$
17,196

 
$
291
v3.8.0.1
Securities (Tables)
 12 Months Ended
Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]  
Securities Available for Sale
The following table summarizes the amortized cost, gross unrealized gains and losses and the resulting fair value of securities available for sale:
 
 
Amortized
Cost
 
Gross
Unrealized
Gains
 
Gross
Unrealized
Losses
 
Fair Value
December 31, 2017
 
(in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
1,752,236

 
$
1,815

 
$
(27,326
)
 
$
1,726,725

State and municipal securities
 
593,940

 
6,023

 
(3,959
)
 
596,004

U.S. government agency and government-sponsored enterprise securities
 
416,894

 
642

 
(2,762
)
 
414,774

U.S. government securities
 
251

 
—

 
(3
)
 
248

Other securities
 
5,284

 
84

 
(288
)
 
5,080

Total
 
$
2,768,605

 
$
8,564

 
$
(34,338
)
 
$
2,742,831

December 31, 2016
 
 
 
 
 
 
 
 
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
1,486,690

 
$
2,760

 
$
(23,718
)
 
$
1,465,732

State and municipal securities
 
473,914

 
6,343

 
(5,197
)
 
475,060

U.S. government agency and government-sponsored enterprise securities
 
332,348

 
1,065

 
(1,511
)
 
331,902

U.S. government securities
 
801

 
—

 
(1
)
 
800

Other securities
 
5,284

 
63

 
(264
)
 
5,083

Total
 
$
2,299,037

 
$
10,231

 
$
(30,691
)
 
$
2,278,577
Schedule of gross realized gains and losses on sales and calls of securities available for sale [Table Text Block]
The following table provides the proceeds and gross realized gains and losses on the sales and calls of securities for the periods indicated:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Proceeds from sales and calls of available for sale securities
 
$
30,403

 
$
124,142

 
$
95,375

 
 
 
 
 
 
 
Gross realized gains
 
$
111

 
$
1,181

 
$
1,591

Gross realized losses
 
(122
)
 
—

 
(10
)
Net realized gains
 
$
(11
)
 
$
1,181

 
$
1,581
Schedule of Contractual Maturities of Investment Securities Available for Sale
The scheduled contractual maturities of investment securities available for sale at December 31, 2017 are presented as follows:
 
 
December 31, 2017
 
 
Amortized Cost
 
Fair Value
 
 
(in thousands)
Due within one year
 
$
124,885

 
$
124,763

Due after one year through five years
 
638,921

 
636,860

Due after five years through ten years
 
804,462

 
796,611

Due after ten years
 
1,195,053

 
1,179,517

Other securities with no stated maturity
 
5,284

 
5,080

Total investment securities available-for-sale
 
$
2,768,605

 
$
2,742,831
Schedule of Securities pledged as collateral [Table Text Block]
The following table summarizes the carrying value of securities pledged as collateral to secure public deposits, borrowings and other purposes as permitted or required by law:
 
 
December 31, 2017
 
December 31, 2016
 
 
(in thousands)
Washington and Oregon State to secure public deposits
 
$
245,222

 
$
232,714

Federal Reserve Bank to secure borrowings
 
52,917

 
33,825

Other securities pledged
 
121,244

 
132,350

Total securities pledged as collateral
 
$
419,383

 
$
398,889
Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses
The following tables show the gross unrealized losses and fair value of the Company’s investments with unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at December 31, 2017 and 2016:
 
 
Less than 12 Months
 
12 Months or More
 
Total
 
 
Fair
Value
 
Unrealized
Losses
 
Fair
Value
 
Unrealized
Losses
 
Fair
Value
 
Unrealized
Losses
December 31, 2017
 
(in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
816,678

 
$
(6,710
)
 
$
717,211

 
$
(20,616
)
 
$
1,533,889

 
(27,326
)
State and municipal securities
 
220,019

 
(1,723
)
 
75,172

 
(2,236
)
 
295,191

 
(3,959
)
U.S. government agency and government-sponsored enterprise securities
 
184,046

 
(1,006
)
 
155,983

 
(1,756
)
 
340,029

 
(2,762
)
U.S. government securities
 
249

 
(3
)
 
—

 
—

 
249

 
(3
)
Other securities
 
—

 
—

 
4,982

 
(288
)
 
4,982

 
(288
)
Total
 
$
1,220,992

 
$
(9,442
)
 
$
953,348

 
$
(24,896
)
 
$
2,174,340

 
$
(34,338
)
December 31, 2016
 
 
 
 
 
 
 
 
 
 
 
 
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
1,029,116

 
$
(18,788
)
 
$
159,046

 
$
(4,930
)
 
$
1,188,162

 
$
(23,718
)
State and municipal securities
 
211,342

 
(5,064
)
 
3,384

 
(133
)
 
214,726

 
(5,197
)
U.S. government agency and government-sponsored enterprise securities
 
218,811

 
(1,511
)
 
—

 
—

 
218,811

 
(1,511
)
U.S. government securities
 
251

 
(1
)
 
—

 
—

 
251

 
(1
)
Other securities
 
2,263

 
(51
)
 
2,743

 
(213
)
 
5,006

 
(264
)
Total
 
$
1,461,783

 
$
(25,415
)
 
$
165,173

 
$
(5,276
)
 
$
1,626,956

 
$
(30,691
)
v3.8.0.1
Loans (Tables)
 12 Months Ended
Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]  
Analysis of Loan Portfolio by Major Types of Loans
The following is an analysis of the loan portfolio by segment (net of unearned income):
 
 
December 31, 2017
 
December 31, 2016
 
 
Loans, excluding PCI loans
 
PCI Loans
 
Total
 
Loans, excluding PCI loans
 
PCI Loans
 
Total
 
 
(in thousands)
Commercial business
 
$
3,377,324

 
$
12,628

 
$
3,389,952

 
$
2,551,054

 
$
20,185

 
$
2,571,239

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
188,396

 
12,395

 
200,791

 
170,331

 
17,862

 
188,193

Commercial and multifamily residential
 
3,825,739

 
75,594

 
3,901,333

 
2,719,830

 
89,231

 
2,809,061

Total real estate
 
4,014,135

 
87,989

 
4,102,124

 
2,890,161

 
107,093

 
2,997,254

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
200,518

 
177

 
200,695

 
121,887

 
832

 
122,719

Commercial and multifamily residential
 
371,931

 
607

 
372,538

 
209,118

 
1,565

 
210,683

Total real estate construction
 
572,449

 
784

 
573,233

 
331,005

 
2,397

 
333,402

Consumer
 
334,190

 
11,269

 
345,459

 
329,261

 
15,985

 
345,246

Less: Net unearned income
 
(52,111
)
 
—

 
(52,111
)
 
(33,718
)
 
—

 
(33,718
)
Total loans, net of unearned income
 
8,245,987

 
112,670

 
8,358,657

 
6,067,763

 
145,660

 
6,213,423

Less: Allowance for loan and lease losses
 
(68,739
)
 
(6,907
)
 
(75,646
)
 
(59,528
)
 
(10,515
)
 
(70,043
)
Total loans, net
 
$
8,177,248

 
$
105,763

 
$
8,283,011

 
$
6,008,235

 
$
135,145

 
$
6,143,380

Loans held for sale
 
$
5,766

 
$
—

 
$
5,766

 
$
5,846

 
$
—

 
$
5,846
Analysis of Nonaccrual Loans
The following is an analysis of nonaccrual loans as of December 31, 2017 and 2016:
 
 
December 31, 2017
 
December 31, 2016
 
 
Recorded
Investment
Nonaccrual
Loans
 
Unpaid Principal
Balance
Nonaccrual
Loans
 
Recorded
Investment
Nonaccrual
Loans
 
Unpaid Principal
Balance
Nonaccrual
Loans
 
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
Secured
 
$
45,410

 
$
56,865

 
$
11,524

 
$
21,503

Unsecured
 
50

 
49

 
31

 
303

Real estate:
 
 
 
 
 
 
 
 
One-to-four family residential
 
785

 
1,182

 
568

 
1,302

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
Commercial land
 
2,628

 
2,623

 
934

 
922

Income property
 
4,284

 
5,410

 
4,005

 
4,247

Owner occupied
 
7,029

 
7,270

 
6,248

 
9,030

Real estate construction:
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
Land and acquisition
 
25

 
26

 
14

 
102

Residential construction
 
1,829

 
1,828

 
549

 
549

Consumer
 
4,149

 
4,633

 
3,883

 
4,331

Total
 
$
66,189

 
$
79,886

 
$
27,756

 
$
42,289
Loans, Excluding Purchased Credit Impaired Loans [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Analysis of the Aged Loan Portfolio
The following is an aging of the recorded investment of the loan portfolio as of December 31, 2017 and 2016:
 
 
Current
Loans
 
30 - 59
Days
Past Due
 
60 - 89
Days
Past Due
 
Greater
than 90
Days Past
Due
 
Total
Past Due
 
Nonaccrual
Loans
 
Total Loans
December 31, 2017
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
3,185,321

 
$
2,530

 
$
2,400

 
$
—

 
$
4,930

 
$
45,410

 
$
3,235,661

Unsecured
 
123,524

 
100

 
501

 
—

 
601

 
50

 
124,175

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
184,256

 
1,111

 
402

 
—

 
1,513

 
785

 
186,554

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
292,680

 
92

 
—

 
581

 
673

 
2,628

 
295,981

Income property
 
1,898,655

 
2,426

 
971

 
—

 
3,397

 
4,284

 
1,906,336

Owner occupied
 
1,590,004

 
2,485

 
468

 
—

 
2,953

 
7,029

 
1,599,986

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
9,882

 
—

 
—

 
—

 
—

 
25

 
9,907

Residential construction
 
187,862

 
—

 
—

 
—

 
—

 
1,829

 
189,691

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
293,028

 
—

 
—

 
—

 
—

 
—

 
293,028

Owner occupied
 
72,443

 
—

 
—

 
—

 
—

 
—

 
72,443

Consumer
 
325,928

 
1,446

 
702

 
—

 
2,148

 
4,149

 
332,225

Total
 
$
8,163,583

 
$
10,190

 
$
5,444

 
$
581

 
$
16,215

 
$
66,189

 
$
8,245,987

 
 
Current
Loans
 
30 - 59
Days
Past Due
 
60 - 89
Days
Past Due
 
Greater
than 90
Days Past
Due
 
Total
Past Due
 
Nonaccrual
Loans
 
Total Loans
December 31, 2016
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
2,439,250

 
$
806

 
$
10

 
$
—

 
$
816

 
$
11,524

 
$
2,451,590

Unsecured
 
94,118

 
287

 
301

 
—

 
588

 
31

 
94,737

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
164,416

 
2,448

 
500

 
—

 
2,948

 
568

 
167,932

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
269,816

 
64

 
—

 
—

 
64

 
934

 
270,814

Income property
 
1,365,150

 
480

 
111

 
—

 
591

 
4,005

 
1,369,746

Owner occupied
 
1,052,078

 
1,652

 
—

 
—

 
1,652

 
6,248

 
1,059,978

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
11,542

 
—

 
—

 
—

 
—

 
14

 
11,556

Residential construction
 
109,080

 
—

 
—

 
—

 
—

 
549

 
109,629

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
103,779

 
—

 
—

 
—

 
—

 
—

 
103,779

Owner occupied
 
103,480

 
—

 
—

 
—

 
—

 
—

 
103,480

Consumer
 
318,369

 
2,035

 
235

 
—

 
2,270

 
3,883

 
324,522

Total
 
$
6,031,078

 
$
7,772

 
$
1,157

 
$
—

 
$
8,929

 
$
27,756

 
$
6,067,763
Impaired Financing Receivables
The following is an analysis of the impaired loans (see Note 1) as of December 31, 2017 and 2016:
 
 
Recorded Investment
of Loans
Collectively Measured
for Contingency
Provision
 
Recorded Investment
of Loans
Individually
Measured for
Specific
Impairment
 
Impaired Loans With
Recorded Allowance
 
Impaired Loans Without
Recorded Allowance
 
 
Recorded
Investment
 
Unpaid
Principal
Balance
 
Related
Allowance
 
Recorded
Investment
 
Unpaid
Principal
Balance
December 31, 2017
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
3,195,649

 
$
40,012

 
$
3,808

 
$
3,937

 
$
1,867

 
$
36,204

 
$
42,314

Unsecured
 
124,150

 
25

 
25

 
24

 
3

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
185,659

 
895

 
867

 
1,408

 
103

 
28

 
337

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
293,694

 
2,287

 
—

 
—

 
—

 
2,287

 
2,282

Income property
 
1,901,313

 
5,023

 
2,768

 
3,328

 
185

 
2,255

 
2,601

Owner occupied
 
1,591,298

 
8,688

 
77

 
80

 
3

 
8,611

 
10,077

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
9,907

 
—

 
—

 
—

 
—

 
—

 
—

Residential construction
 
188,481

 
1,210

 
—

 
—

 
—

 
1,210

 
1,210

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
293,028

 
—

 
—

 
—

 
—

 
—

 
—

Owner occupied
 
68,393

 
4,050

 
—

 
—

 
—

 
4,050

 
4,050

Consumer
 
325,210

 
7,015

 
5,303

 
5,568

 
199

 
1,712

 
1,864

Total
 
$
8,176,782

 
$
69,205

 
$
12,848

 
$
14,345

 
$
2,360

 
$
56,357

 
$
64,735

 
 
 
Recorded Investment
of Loans
Collectively Measured
for Contingency
Provision
 
Recorded Investment
of Loans
Individually
Measured for
Specific
Impairment
 
Impaired Loans With
Recorded Allowance
 
Impaired Loans Without
Recorded Allowance
 
 
Recorded
Investment
 
Unpaid
Principal
Balance
 
Related
Allowance
 
Recorded
Investment
 
Unpaid
Principal
Balance
December 31, 2016
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
2,442,772

 
$
8,818

 
$
2,414

 
$
2,484

 
$
664

 
$
6,404

 
$
12,831

Unsecured
 
94,737

 
—

 
—

 
—

 
—

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
167,403

 
529

 
435

 
693

 
12

 
94

 
291

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
270,106

 
708

 
—

 
—

 
—

 
708

 
687

Income property
 
1,365,321

 
4,425

 
540

 
544

 
27

 
3,885

 
4,148

Owner occupied
 
1,054,564

 
5,414

 
—

 
—

 
—

 
5,414

 
8,102

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
11,542

 
14

 
14

 
102

 
1

 
—

 
—

Residential construction
 
109,293

 
336

 
—

 
—

 
—

 
336

 
336

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
103,779

 
—

 
—

 
—

 
—

 
—

 
—

Owner occupied
 
103,480

 
—

 
—

 
—

 
—

 
—

 
—

Consumer
 
319,307

 
5,215

 
4,464

 
4,558

 
57

 
751

 
833

Total
 
$
6,042,304

 
$
25,459

 
$
7,867

 
$
8,381

 
$
761

 
$
17,592

 
$
27,228


The following table provides additional information on impaired loans for the years ended December 31, 2017, 2016 and 2015:
 
 
Year Ended December 31, 2017
 
Year Ended December 31, 2016
 
Year Ended December 31, 2015
 
 
Average Recorded
Investment
Impaired Loans 
 
Interest Recognized
on
Impaired Loans
 
Average Recorded
Investment
Impaired Loans 
 
Interest Recognized
on
Impaired Loans
 
Average Recorded
Investment
Impaired Loans 
 
Interest Recognized
on
Impaired Loans
 
 
(in thousands)
Commercial business
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
20,282

 
$
60

 
$
9,368

 
$
79

 
$
7,987

 
$
84

Unsecured
 
5

 
—

 
—

 
—

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
730

 
49

 
743

 
10

 
2,848

 
47

Commercial & multifamily residential
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
2,079

 
—

 
425

 
—

 
94

 
—

Income property
 
4,314

 
51

 
2,492

 
26

 
2,913

 
36

Owner occupied
 
5,335

 
445

 
5,084

 
—

 
7,052

 
26

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
3

 
—

 
199

 
—

 
641

 
5

Residential construction
 
309

 
—

 
472

 
—

 
648

 
—

Commercial & multifamily residential
 
 
 
 
 
 
 
 
 
 
 
 
Owner occupied
 
1,620

 
203

 
—

 
—

 
—

 
—

Consumer
 
5,973

 
163

 
2,710

 
122

 
189

 
4

Total
 
$
40,650

 
$
971

 
$
21,493

 
$
237

 
$
22,372

 
$
202
Analysis of loans classified as Troubled Debt Restructurings (“TDR”)
The following is an analysis of loans classified as troubled debt restructurings (“TDR”) for the years ended December 31, 2017, 2016 and 2015:
 
 
Year Ended December 31, 2017
 
Year Ended December 31, 2016
 
Year Ended December 31, 2015
 
 
Number of TDR Modifications
 
Pre-Modification
Outstanding
Recorded
Investment
 
Post-Modification
Outstanding
Recorded
Investment
 
Number of TDR Modifications
 
Pre-Modification
Outstanding
Recorded
Investment
 
Post-Modification
Outstanding
Recorded
Investment
 
Number of TDR Modifications
 
Pre-Modification
Outstanding
Recorded
Investment
 
Post-Modification
Outstanding
Recorded
Investment
 
 
(dollars in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
10

 
$
5,655

 
$
5,655

 
9

 
$
2,131

 
$
2,131

 
5

 
$
3,724

 
$
3,706

Unsecured
 
1

 
26

 
26

 
—

 
—

 
—

 
—

 
—

 
—

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
3

 
583

 
583

 
3

 
203

 
203

 
1

 
30

 
30

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
1

 
687

 
687

 
—

 
—

 
—

 
—

 
—

 
—

Income property
 
1

 
1,152

 
1,152

 
—

 
—

 
—

 
—

 
—

 
—

Owner occupied
 
1

 
78

 
78

 
1

 
250

 
250

 
—

 
—

 
—

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Owner occupied
 
1

 
4,050

 
4,050

 
—

 
—

 
—

 
—

 
—

 
—

Consumer
 
42

 
5,891

 
5,891

 
41

 
5,095

 
5,093

 
1

 
54

 
54

Total
 
60

 
$
18,122

 
$
18,122

 
54

 
$
7,679

 
$
7,677

 
7

 
$
3,808

 
$
3,790
Purchased Credit Impaired Loans [Member]  
Financing Receivable, Recorded Investment [Line Items]  
Analysis of Loan Portfolio by Major Types of Loans
The following is an analysis of our PCI loans, net of related allowance for losses and remaining valuation discounts as of December 31, 2017 and 2016:
 
 
December 31, 2017
 
December 31, 2016
 
 
(in thousands)
Commercial business
 
$
13,753

 
$
21,606

Real estate:
 
 
 
 
One-to-four family residential
 
14,610

 
20,643

Commercial and multifamily residential
 
79,211

 
94,795

Total real estate
 
93,821

 
115,438

Real estate construction:
 
 
 
 
One-to-four family residential
 
177

 
832

Commercial and multifamily residential
 
595

 
1,726

Total real estate construction
 
772

 
2,558

Consumer
 
12,412

 
17,649

Subtotal of purchased credit impaired loans
 
120,758

 
157,251

Less:
 
 
 
 
Valuation discount resulting from acquisition accounting
 
8,088

 
11,591

Allowance for loan losses
 
6,907

 
10,515

PCI loans, net of valuation discounts and allowance for loan losses
 
$
105,763

 
$
135,145
Changes in Accretable Yield for Acquired Loans [Table Text Block]
The following table shows the changes in accretable yield for acquired loans for the years ended December 31, 2017, 2016, and 2015:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Balance at beginning of period
 
$
45,191

 
$
58,981

 
$
73,849

Accretion
 
(12,357
)
 
(16,266
)
 
(21,919
)
Disposals
 
(158
)
 
(148
)
 
(1,681
)
Reclassifications from (to) nonaccretable difference
 
(1,500
)
 
2,624

 
8,732

Balance at end of period
 
$
31,176

 
$
45,191

 
$
58,981
v3.8.0.1
Allowance for Loan and Lease Losses and Unfunded Commitments and Letters of Credit (Tables)
 12 Months Ended
Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]  
Changes in the Allowance for Loan and Lease Losses
The following tables show a detailed analysis of the allowance for loans for the years ended December 31, 2017, 2016 and 2015:
 
 
Beginning
Balance
 
Charge-offs
 
Recoveries
 
Provision (Recovery)
 
Ending
Balance
 
Specific
Reserve
 
General
Allocation
Year Ended December 31, 2017
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
36,050

 
$
(7,524
)
 
$
4,283

 
$
(3,468
)
 
$
29,341

 
$
1,867

 
$
27,474

Unsecured
 
960

 
(89
)
 
553

 
576

 
2,000

 
3

 
1,997

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
599

 
(460
)
 
568

 
(6
)
 
701

 
103

 
598

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
1,797

 
—

 
53

 
2,415

 
4,265

 
—

 
4,265

Income property
 
7,342

 
(287
)
 
498

 
(1,881
)
 
5,672

 
185

 
5,487

Owner occupied
 
6,439

 
—

 
124

 
(1,104
)
 
5,459

 
3

 
5,456

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
316

 
(14
)
 
72

 
589

 
963

 
—

 
963

Residential construction
 
669

 
—

 
106

 
2,934

 
3,709

 
—

 
3,709

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
404

 
—

 
1

 
6,648

 
7,053

 
—

 
7,053

Owner occupied
 
1,192

 
—

 
—

 
3,221

 
4,413

 
—

 
4,413

Consumer
 
3,534

 
(1,474
)
 
1,187

 
1,916

 
5,163

 
199

 
4,964

Purchased credit impaired
 
10,515

 
(6,812
)
 
6,187

 
(2,983
)
 
6,907

 
—

 
6,907

Unallocated
 
226

 
—

 
—

 
(226
)
 
—

 
—

 
—

Total
 
$
70,043

 
$
(16,660
)
 
$
13,632

 
$
8,631

 
$
75,646

 
$
2,360

 
$
73,286

 
 
Beginning
Balance
 
Charge-offs
 
Recoveries
 
Provision (Recovery)
 
Ending
Balance
 
Specific
Reserve
 
General
Allocation
Year Ended December 31, 2016
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
32,321

 
$
(9,993
)
 
$
2,483

 
$
11,239

 
$
36,050

 
$
664

 
$
35,386

Unsecured
 
1,299

 
(75
)
 
162

 
(426
)
 
960

 
—

 
960

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
916

 
(35
)
 
171

 
(453
)
 
599

 
12

 
587

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
1,178

 
(26
)
 
2

 
643

 
1,797

 
—

 
1,797

Income property
 
6,616

 
—

 
966

 
(240
)
 
7,342

 
27

 
7,315

Owner occupied
 
5,550

 
(63
)
 
434

 
518

 
6,439

 
—

 
6,439

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
339

 
(88
)
 
57

 
8

 
316

 
1

 
315

Residential construction
 
733

 
—

 
234

 
(298
)
 
669

 
—

 
669

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
388

 
—

 
109

 
(93
)
 
404

 
—

 
404

Owner occupied
 
1,006

 
—

 
—

 
186

 
1,192

 
—

 
1,192

Consumer
 
3,531

 
(1,238
)
 
933

 
308

 
3,534

 
57

 
3,477

Purchased credit impaired
 
13,726

 
(9,944
)
 
7,004

 
(271
)
 
10,515

 
—

 
10,515

Unallocated
 
569

 
—

 
—

 
(343
)
 
226

 
—

 
226

Total
 
$
68,172

 
$
(21,462
)
 
$
12,555

 
$
10,778

 
$
70,043

 
$
761

 
$
69,282


 
 
Beginning
Balance
 
Charge-offs
 
Recoveries
 
Provision (Recovery)
 
Ending
Balance
 
Specific
Reserve
 
General
Allocation
Year ended December 31, 2015
 
(in thousands)
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
25,923

 
$
(7,486
)
 
$
2,069

 
$
11,815

 
$
32,321

 
$
321

 
$
32,000

Unsecured
 
927

 
(780
)
 
267

 
885

 
1,299

 
—

 
1,299

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
2,281

 
(376
)
 
307

 
(1,296
)
 
916

 
314

 
602

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
799

 
—

 
291

 
88

 
1,178

 
—

 
1,178

Income property
 
9,159

 
(390
)
 
3,568

 
(5,721
)
 
6,616

 
—

 
6,616

Owner occupied
 
5,007

 
(115
)
 
116

 
542

 
5,550

 
—

 
5,550

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
1,197

 
—

 
103

 
(961
)
 
339

 
—

 
339

Residential construction
 
1,860

 
—

 
90

 
(1,217
)
 
733

 
3

 
730

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
622

 
—

 
8

 
(242
)
 
388

 
—

 
388

Owner occupied
 
434

 
—

 
—

 
572

 
1,006

 
—

 
1,006

Consumer
 
3,180

 
(2,066
)
 
931

 
1,486

 
3,531

 
15

 
3,516

Purchased credit impaired
 
16,336

 
(13,854
)
 
7,329

 
3,915

 
13,726

 
—

 
13,726

Unallocated
 
1,844

 
—

 
—

 
(1,275
)
 
569

 
—

 
569

Total
 
$
69,569

 
$
(25,067
)
 
$
15,079

 
$
8,591

 
$
68,172

 
$
653

 
$
67,519
Changes in the Allowance for Unfunded Commitments and Letters of Credit
Changes in the allowance for unfunded commitments and letters of credit, a component of “Other liabilities” in the Consolidated Balance Sheets, are summarized as follows:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Beginning balance
 
$
2,705

 
$
2,930

 
$
2,655

Net changes in the allowance for unfunded commitments and letters of credit
 
425

 
(225
)
 
275

Ending balance
 
$
3,130

 
$
2,705

 
$
2,930
Financing Receivable Credit Quality Indicators [Table Text Block]
The following is an analysis of the credit quality of our loan portfolio, excluding PCI loans as of December 31, 2017 and 2016:
 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2017
 
(in thousands)
Loans, excluding PCI loans
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
3,049,031

 
$
64,600

 
$
122,030

 
$
—

 
$
—

 
$
3,235,661

Unsecured
 
123,621

 
—

 
554

 
—

 
—

 
124,175

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
183,312

 
1,186

 
2,056

 
—

 
—

 
186,554

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
283,673

 
5,204

 
7,104

 
—

 
—

 
295,981

Income property
 
1,857,832

 
17,181

 
31,323

 
—

 
—

 
1,906,336

Owner occupied
 
1,546,775

 
7,380

 
45,831

 
—

 
—

 
1,599,986

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
9,882

 
—

 
25

 
—

 
—

 
9,907

Residential construction
 
187,863

 
—

 
1,828

 
—

 
—

 
189,691

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
293,028

 
—

 
—

 
—

 
—

 
293,028

Owner occupied
 
68,393

 
—

 
4,050

 
—

 
—

 
72,443

Consumer
 
323,129

 
—

 
9,096

 
—

 
—

 
332,225

Total
 
$
7,926,539

 
$
95,551

 
$
223,897

 
$
—

 
$
—

 
8,245,987

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Allowance for loan losses
 
68,739

Loans, excluding PCI loans, net
 
$
8,177,248

 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2016
 
(in thousands)
Loans, excluding PCI loans
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
2,289,307

 
$
65,846

 
$
96,437

 
$
—

 
$
—

 
$
2,451,590

Unsecured
 
93,721

 
800

 
216

 
—

 
—

 
94,737

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
164,797

 
395

 
2,740

 
—

 
—

 
167,932

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
263,195

 
3,228

 
4,391

 
—

 
—

 
270,814

Income property
 
1,341,978

 
17,902

 
9,866

 
—

 
—

 
1,369,746

Owner occupied
 
1,027,019

 
6,608

 
26,351

 
—

 
—

 
1,059,978

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
11,541

 
—

 
15

 
—

 
—

 
11,556

Residential construction
 
108,941

 
—

 
688

 
—

 
—

 
109,629

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
103,779

 
—

 
—

 
—

 
—

 
103,779

Owner occupied
 
98,948

 
88

 
4,444

 
—

 
—

 
103,480

Consumer
 
317,728

 
—

 
6,794

 
—

 
—

 
324,522

Total
 
$
5,820,954

 
$
94,867

 
$
151,942

 
$
—

 
$
—

 
6,067,763

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Allowance for loan losses
 
59,528

Loans, excluding PCI loans, net
 
$
6,008,235


The following is an analysis of the credit quality of our PCI loan portfolio as of December 31, 2017 and 2016:
 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2017
 
(in thousands)
PCI loans:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
11,918

 
$
—

 
$
723

 
$
—

 
$
—

 
$
12,641

Unsecured
 
1,045

 
—

 
67

 
—

 
—

 
1,112

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
13,817

 
—

 
793

 
—

 
—

 
14,610

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
9,460

 
349

 
—

 
—

 
—

 
9,809

Income property
 
25,981

 
—

 
35

 
—

 
—

 
26,016

Owner occupied
 
42,617

 
—

 
769

 
—

 
—

 
43,386

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
169

 
—

 
8

 
—

 
—

 
177

Residential construction
 
—

 
—

 
—

 
—

 
—

 
—

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
595

 
—

 
—

 
—

 
—

 
595

Owner occupied
 
—

 
—

 
—

 
—

 
—

 
—

Consumer
 
11,705

 
—

 
707

 
—

 
—

 
12,412

Total
 
$
117,307

 
$
349

 
$
3,102

 
$
—

 
$
—

 
120,758

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Valuation discount resulting from acquisition accounting
 
8,088

Allowance for loan losses
 
6,907

PCI loans, net
 
$
105,763

 
 
Pass
 
Special Mention
 
Substandard
 
Doubtful
 
Loss
 
Total
December 31, 2016
 
(in thousands)
PCI loans:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial business:
 
 
 
 
 
 
 
 
 
 
 
 
Secured
 
$
18,824

 
$
92

 
$
1,954

 
$
—

 
$
—

 
$
20,870

Unsecured
 
736

 
—

 
—

 
—

 
—

 
736

Real estate:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential
 
19,293

 
—

 
1,350

 
—

 
—

 
20,643

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Commercial land
 
7,333

 
—

 
213

 
—

 
—

 
7,546

Income property
 
31,042

 
—

 
1,678

 
—

 
—

 
32,720

Owner occupied
 
53,623

 
—

 
906

 
—

 
—

 
54,529

Real estate construction:
 
 
 
 
 
 
 
 
 
 
 
 
One-to-four family residential:
 
 
 
 
 
 
 
 
 
 
 
 
Land and acquisition
 
744

 
—

 
88

 
—

 
—

 
832

Residential construction
 
—

 
—

 
—

 
—

 
—

 
—

Commercial and multifamily residential:
 
 
 
 
 
 
 
 
 
 
 
 
Income property
 
1,217

 
—

 
—

 
—

 
—

 
1,217

Owner occupied
 
509

 
—

 
—

 
—

 
—

 
509

Consumer
 
17,202

 
—

 
447

 
—

 
—

 
17,649

Total
 
$
150,523

 
$
92

 
$
6,636

 
$
—

 
$
—

 
157,251

Less:
 
 
 
 
 
 
 
 
 
 
 
 
Valuation discount resulting from acquisition accounting
 
11,591

Allowance for loan losses
 
10,515

PCI loans, net
 
$
135,145
v3.8.0.1
Other Real Estate Owned (Tables)
 12 Months Ended
Dec. 31, 2017
Other Real Estate, Foreclosed Assets, and Repossessed Assets [Abstract]  
Summary of Other Real Estate Owned
The following table sets forth activity in OREO for the period:
 
 
December 31, 2017
 
December 31, 2016
 
 
(in thousands)
Balance, beginning of period
 
$
5,998

 
$
13,738

Established through acquisitions
 
10,279

 
—

Transfers in
 
106

 
1,047

Valuation adjustments
 
(364
)
 
(860
)
Proceeds from sale of OREO property
 
(2,590
)
 
(8,158
)
Gain (loss) on sale of OREO, net
 
(131
)
 
231

Balance, end of period
 
$
13,298

 
$
5,998
v3.8.0.1
FDIC Loss-sharing Asset and Covered Assets (Tables)
 12 Months Ended
Dec. 31, 2017
Covered Assets And FDIC Loss Sharing Asset [Line Items]  
FDIC Loss-sharing Asset
The following table shows a detailed analysis of the FDIC loss-sharing asset for the years ending December 31, 2017 and 2016:
 
 
2017
 
2016
 
 
(in thousands)
Balance at beginning of period
 
$
3,535

 
$
6,568

Adjustments not reflected in income:
 
 
 
 
Cash paid to the FDIC, net
 
184

 
705

FDIC shared recoveries, net
 
(149
)
 
(1,153
)
Termination of FDIC loss-sharing agreements
 
(3,123
)
 
—

Adjustments reflected in noninterest income (1):
 
 
 
 
Amortization, net
 
(414
)
 
(2,829
)
Loan impairment
 
40

 
301

Sale of other real estate
 
18

 
148

Valuation adjustments of other real estate
 
—

 
(22
)
Other
 
(91
)
 
(183
)
Balance at end of period
 
$
—

 
$
3,535
v3.8.0.1
Premises and Equipment (Tables)
 12 Months Ended
Dec. 31, 2017
Property, Plant and Equipment [Abstract]  
Property, Plant and Equipment
Real and personal property and software, less accumulated depreciation and amortization, were as follows:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Land
 
$
54,510

 
$
47,438

Buildings
 
110,216

 
101,196

Leasehold improvements
 
24,184

 
19,491

Furniture and equipment
 
30,486

 
26,709

Vehicles
 
473

 
536

Computer software
 
20,384

 
18,657

Total cost
 
240,253

 
214,027

Less accumulated depreciation and amortization
 
(70,763
)
 
(63,685
)
Total
 
$
169,490

 
$
150,342
v3.8.0.1
Goodwill and Intangible Assets (Tables)
 12 Months Ended
Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]  
Schedule of Goodwill and Intangible Assets
The following table sets forth activity for goodwill and other intangible assets for the period:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Goodwill, beginning of period
 
$
382,762

 
$
382,762

 
$
382,537

Established through acquisitions and provisional period adjustments (1)
 
383,080

 
—

 
225

Total goodwill, end of period
 
765,842

 
382,762

 
382,762

Other intangible assets, net
 
 
 
 
 
 
Core deposit intangible:
 
 
 
 
 
 
Gross core deposit intangible balance, beginning of period
 
58,598

 
58,598

 
58,598

Accumulated amortization, beginning of period
 
(41,886
)
 
(35,940
)
 
(29,058
)
Core deposit intangible, net, beginning of period
 
16,712

 
22,658

 
29,540

Established through acquisition
 
46,875

 
—

 
—

CDI current period amortization
 
(6,333
)
 
(5,946
)
 
(6,882
)
Total core deposit intangible, end of period
 
57,254

 
16,712

 
22,658

Intangible assets not subject to amortization
 
919

 
919

 
919

Other intangible assets, net at end of period
 
58,173

 
17,631

 
23,577

Total goodwill and intangible assets, end of period
 
$
824,015

 
$
400,393

 
$
406,339
Estimated Future Amortization Expense of Core Deposit Intangibles
The following table provides the estimated future amortization expense of core deposit intangibles for the succeeding five years:
Years Ending December 31,
 
(in thousands)
2018
 
$
12,235

2019
 
10,479

2020
 
8,724

2021
 
7,264

2022
 
5,880
v3.8.0.1
Deposits (Tables)
 12 Months Ended
Dec. 31, 2017
Deposits [Abstract]  
Schedule Of Deposits
Year-end deposits are summarized in the following table:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Core deposits:
 
 
 
 
Demand and other noninterest-bearing
 
$
5,081,901

 
$
3,944,495

Interest-bearing demand
 
1,265,212

 
985,293

Money market
 
2,543,712

 
1,791,283

Savings
 
861,941

 
723,667

Certificates of deposit, less than $250,000
 
286,791

 
304,830

Total core deposits
 
10,039,557

 
7,749,568

Certificates of deposit, $250,000 or more
 
100,399

 
79,424

Certificates of deposit insured through CDARS®
 
25,374

 
22,039

Other brokered certificates of deposits
 
78,481

 
—

Brokered money market accounts
 
289,031

 
208,348

Subtotal
 
10,532,842

 
8,059,379

Valuation adjustment resulting from acquisition accounting
 
(757
)
 
36

Total deposits
 
$
10,532,085

 
$
8,059,415
Schedule Of Time Deposits Maturity
The following table shows the amount and maturity of time deposits:
Years Ending December 31,
 
(in thousands)
2018
 
$
338,958

2019
 
74,177

2020
 
34,727

2021
 
20,857

2022
 
12,600

Thereafter
 
9,726

Total
 
$
491,045
v3.8.0.1
Federal Home Loan Bank and Federal Reserve Bank Borrowings (Tables)
 12 Months Ended
Dec. 31, 2017
Federal Home Loan Bank Advances [Member]  
Debt Instrument [Line Items]  
Schedule of Maturities of Long-term Debt
At December 31, 2017, FHLB advances were scheduled to mature as follows:
 
 
Federal Home Loan Bank Advances
Fixed rate advances
 
 
Weighted Average Rate
 
Amount
 
 
(dollars in thousands)
Within 1 year
 
2.58
%
 
$
4,000

Over 1 through 5 years
 
3.85
%
 
2,000

Due after 10 years
 
5.37
%
 
5,000

Total
 
11,000

Valuation adjustment from acquisition accounting
 
579

Total
 
$
11,579
Debt Instrument Activity For Year
The maximum, average outstanding and year-end balances and average interest rates on advances from the FHLB were as follows for the years ended December 31, 2017, 2016 and 2015:
 
 
Years ended December 31,
 
 
2017
 
2016
 
2015
 
 
(dollars in thousands)
Balance at end of period
 
$
11,579

 
$
6,493

 
$
68,531

Average balance during period
 
$
79,788

 
$
79,673

 
$
70,678

Maximum month-end balance during period
 
$
317,480

 
$
250,515

 
$
242,556

Weighted average rate during period
 
1.33
%
 
0.80
%
 
0.68
%
Weighted average rate at December 31
 
4.08
%
 
5.42
%
 
0.79
%
Schedule of Financial Instruments Owned and Pledged as Collateral
FHLB advances are collateralized by the following:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Recorded value of blanket pledge on loans receivable
 
$
1,443,554

 
$
1,510,514

Total
 
$
1,443,554

 
$
1,510,514

FHLB borrowing capacity
 
$
1,432,554

 
$
1,502,284
Federal Reserve Bank Advances [Member]  
Debt Instrument [Line Items]  
Schedule of Financial Instruments Owned and Pledged as Collateral
The following table shows amounts pledged to the Federal Reserve Bank:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Fair value of investment securities
 
$
51,172

 
$
32,795

Recorded value of pledged commercial loans
 
48,882

 
28,212

Total
 
$
100,054

 
$
61,007

Federal Reserve Bank borrowing capacity
 
$
100,054

 
$
61,007
v3.8.0.1
Derivatives and Balance Sheet Offsetting (Tables)
 12 Months Ended
Dec. 31, 2017
Derivative [Line Items]  
Balance Sheet Offsetting [Table Text Block]
The following tables show the gross interest rate swap agreements and repurchase agreements in the Consolidated Balance Sheets and the respective collateral received or pledged in the form of other financial instruments, which are generally marketable securities. The collateral amounts in these tables are limited to the outstanding balances of the related asset or liability. Therefore, instances of overcollateralization are not shown.
 
Gross Amounts of Recognized Assets/Liabilities
 
Gross Amounts Offset in the Consolidated Balance Sheets
 
Net Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheets
 
Gross Amounts Not Offset in the Consolidated Balance Sheets
 
 
 
 
Collateral Posted
 
Net Amount
December 31, 2017
(in thousands)
Assets
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
6,707

 
$
—

 
$
6,707

 
$
—

 
$
6,707

Liabilities
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
6,714

 
$
—

 
$
6,714

 
$
(6,714
)
 
$
—

Repurchase agreements
$
79,059

 
$
—

 
$
79,059

 
$
(79,059
)
 
$
—

 
 
 
 
 
 
 
 
 
 
December 31, 2016
 
 
 
 
 
 
 
 
 
Assets
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
9,012

 
$
—

 
$
9,012

 
$
—

 
$
9,012

Liabilities
 
 
 
 
 
 
 
 
 
Interest rate contracts
$
9,036

 
$
—

 
$
9,036

 
$
(9,036
)
 
$
—

Repurchase agreements
$
80,822

 
$
—

 
$
80,822

 
$
(80,822
)
 
$
—
Not Designated as Hedging Instrument [Member]  
Derivative [Line Items]  
Schedule of Fair Value Derivative Instruments
The following table presents the fair value and balance sheet classification of derivatives not designated as hedging instruments at December 31, 2017 and 2016:
 
Asset Derivatives
 
Liability Derivatives
 
2017
 
2016
 
2017
 
2016
(in thousands)
Balance Sheet
Location
 
Fair Value
 
Balance Sheet
Location
 
Fair Value
 
Balance Sheet
Location
 
Fair Value
 
Balance Sheet
Location
 
Fair Value
Interest rate contracts
Other assets
 
$
6,707

 
Other assets
 
$
9,012

 
Other liabilities
 
$
6,714

 
Other liabilities
 
$
9,036
Available-for-sale Securities [Member]  
Derivative [Line Items]  
Schedule of Financial Instruments Owned and Pledged as Collateral [Table Text Block]
The following table presents the class of collateral pledged for repurchase agreements as well as the remaining contractual maturity of the repurchase agreements:
 
 
Remaining contractual maturity of the agreements
 
 
Overnight and continuous
 
Up to 30 days
 
30 - 90 days
 
Greater than 90 days
 
Total
December 31, 2017
 
(in thousands)
Class of collateral pledged for repurchase agreements
 
 
 
 
 
 
 
 
 
 
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations
 
$
54,059

 
$
—

 
$
25,000

 
$
—

 
$
79,059

Gross amount of recognized liabilities for repurchase agreements
 
79,059

Amounts related to agreements not included in offsetting disclosure
 
$
—
v3.8.0.1
Employee Benefit Plans (Tables)
 12 Months Ended
Dec. 31, 2017
Employee Benefit [Line Items]  
Schedule of Accumulated and Projected Benefit Obligations
The following table reconciles the accumulated liability for the projected benefit obligation:
 
 
December 31,
2017
 
2016
 
 
(in thousands)
Balance at beginning of year
 
$
26,263

 
$
25,544

Change in actuarial loss (gain)
 
(6,453
)
 
62

Plan amendments
 
148

 
—

Benefit expense
 
1,600

 
2,201

Benefit payments
 
(1,005
)
 
(1,544
)
Balance at end of year
 
$
20,553

 
$
26,263
SERP [Member]  
Employee Benefit [Line Items]  
Schedule of Expected Benefit Payments
The benefits expected to be paid in conjunction with the SERP are presented in the following table:
Years Ending December 31,
 
(in thousands)
2018
 
$
936

2019
 
963

2020
 
1,971

2021
 
2,095

2022
 
1,135

2023 through 2027
 
7,563

Total
 
$
14,663
v3.8.0.1
Commitments and Contingent Liabilities (Tables)
 12 Months Ended
Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]  
Schedule of Future Minimum Rental Payments for Operating Leases
As of December 31, 2017, minimum future rental payments, exclusive of taxes and other charges, of these leases were:
Years Ending December 31,
 
(in thousands)
2018
 
$
10,994

2019
 
10,458

2020
 
8,730

2021
 
7,104

2022
 
6,303

Thereafter
 
14,482

Total minimum payments
 
$
58,071
v3.8.0.1
Accumulated Other Comprehensive Income (Tables)
 12 Months Ended
Dec. 31, 2017
Accumulated Other Comprehensive Income [Abstract]  
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
The following table shows changes in accumulated other comprehensive income (loss) by component for the years ended December 31, 2017, 2016 and 2015:
 
 
Unrealized Gains and Losses on Available-for-Sale Securities (1)
 
Unrealized Gains and Losses on Pension Plan Liability (1)
 
Total (1)
Year Ended December 31, 2017
 
(in thousands)
Beginning balance
 
$
(12,704
)
 
$
(6,295
)
 
$
(18,999
)
Other comprehensive income (loss) before reclassifications
 
(3,391
)
 
4,017

 
626

Amounts reclassified from accumulated other comprehensive loss (2)
 
7

 
223

 
230

Net current-period other comprehensive income (loss)
 
(3,384
)
 
4,240

 
856

Adjustment pursuant to adoption of ASU 2018-02
 
(3,691
)
 
(391
)
 
(4,082
)
Ending balance
 
$
(19,779
)
 
$
(2,446
)
 
$
(22,225
)
Year Ended December 31, 2016
 
 
 
 
 
 
Beginning balance
 
$
386

 
$
(6,681
)
 
$
(6,295
)
Other comprehensive loss before reclassifications
 
(12,338
)
 
(39
)
 
(12,377
)
Amounts reclassified from accumulated other comprehensive loss (2)
 
(752
)
 
425

 
(327
)
Net current-period other comprehensive income (loss)
 
(13,090
)
 
386

 
(12,704
)
Ending balance
 
$
(12,704
)
 
$
(6,295
)
 
$
(18,999
)
Year Ended December 31, 2015
 
 
 
 
 
 
Beginning balance
 
$
7,462

 
$
(1,841
)
 
$
5,621

Other comprehensive loss before reclassifications
 
(6,069
)
 
(5,054
)
 
(11,123
)
Amounts reclassified from accumulated other comprehensive income (2)
 
(1,007
)
 
214

 
(793
)
Net current-period other comprehensive loss
 
(7,076
)
 
(4,840
)
 
(11,916
)
Ending balance
 
$
386

 
$
(6,681
)
 
$
(6,295
)
__________
(1) All amounts are net of tax. Amounts in parenthesis indicate debits.
(2) See following table for details about these reclassifications.
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]
The following table shows details regarding the reclassifications from accumulated other comprehensive income for the years ended December 31, 2017, 2016 and 2015:
 
 
Amount Reclassified from Accumulated Other Comprehensive Income
 
Affected line Item in the Consolidated Statement of Income
 
 
Years Ended
 
 
 
 
December 31, 2017
 
December 31, 2016
 
December 31, 2015
 
 
 
 
(in thousands)
 
 
Unrealized gains and losses on available-for-sale securities
 
$
(11
)
 
$
1,181

 
$
1,581

 
Investment securities gains (losses), net
 
 
(11
)
 
1,181

 
1,581

 
Total before tax
 
 
4

 
(429
)
 
(574
)
 
Income tax benefit (provision)
 
 
$
(7
)
 
$
752

 
$
1,007

 
Net of tax
 
 
 
 
 
 
 
 
 
Amortization of pension plan liability
actuarial losses
 
$
(350
)
 
$
(668
)
 
$
(336
)
 
Compensation and employee benefits
 
 
(350
)
 
(668
)
 
(336
)
 
Total before tax
 
 
127

 
243

 
122

 
Income tax benefit
 
 
$
(223
)
 
$
(425
)
 
$
(214
)
 
Net of tax
v3.8.0.1
Fair Value Accounting and Measurement (Tables)
 12 Months Ended
Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Financial Assets And Liabilities Accounted For Fair Value On Recurring Basis
The following table sets forth the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis at December 31, 2017 and 2016 by level within the fair value hierarchy. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement:
 
 
Fair value  at
December 31, 2017
 
Fair Value Measurements at Reporting Date Using
 
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
Securities available for sale
 
 
 
 
 
 
 
 
U.S. government agency and sponsored enterprise mortgage-back securities and collateralized mortgage obligations
 
$
1,726,725

 
$
—

 
$
1,726,725

 
$
—

State and municipal securities
 
596,004

 
—

 
596,004

 
—

U.S. government agency and government-sponsored enterprise securities
 
414,774

 
—

 
414,774

 
—

U.S. government securities
 
248

 
248

 
—

 
—

Other securities
 
5,080

 
5,080

 
—

 
—

Total securities available for sale
 
$
2,742,831

 
$
5,328

 
$
2,737,503

 
$
—

Other assets (Interest rate contracts)
 
$
6,707

 
$
—

 
$
6,707

 
$
—

Liabilities
 
 
 
 
 
 
 
 
Other liabilities (Interest rate contracts)
 
$
6,714

 
$
—

 
$
6,714

 
$
—

 
 
Fair value  at
December 31, 2016
 
Fair Value Measurements at Reporting Date Using
 
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
Securities available for sale
 
 
 
 
 
 
 
 
U.S. government agency and sponsored enterprise mortgage-back securities and collateralized mortgage obligations
 
$
1,465,732

 
$
—

 
$
1,465,732

 
$
—

State and municipal debt securities
 
475,060

 
—

 
475,060

 
—

U.S. government agency and government-sponsored enterprise securities
 
331,902

 
—

 
331,902

 
—

U.S. government securities
 
800

 
800

 
—

 
—

Other securities
 
5,083

 
—

 
5,083

 
—

Total securities available for sale
 
$
2,278,577

 
$
800

 
$
2,277,777

 
$
—

Other assets (Interest rate contracts)
 
$
9,012

 
$
—

 
$
9,012

 
$
—

Liabilities
 
 
 
 
 
 
 
 
Other liabilities (Interest rate contracts)
 
$
9,036

 
$
—

 
$
9,036

 
$
—
Financial Assets Accounted For Fair Value On Nonrecurring Basis
The following table sets forth the Company’s assets that were measured using fair value estimates on a nonrecurring basis during the years ended December 31, 2017 and 2016:
 
 
Fair value  at
December 31, 2017
 
Fair Value Measurements at Reporting Date Using
 
Losses During the Year Ended
December 31, 2017
 
 
Level 1
 
Level 2
 
Level 3
 
 
 
(in thousands)
Impaired loans
 
$
6,577

 
$
—

 
$
—

 
$
6,577

 
$
2,507

OREO
 
1,423

 
—

 
—

 
1,423

 
239

 
 
$
8,000

 
$
—

 
$
—

 
$
8,000

 
$
2,746

 
 
Fair value  at
December 31, 2016
 
Fair Value Measurements at Reporting Date Using
 
Losses During the Year Ended
December 31, 2016
 
 
Level 1
 
Level 2
 
Level 3
 
 
 
(in thousands)
Impaired loans
 
$
3,787

 
$
—

 
$
—

 
$
3,787

 
$
5,413

OREO
 
4,388

 
—

 
—

 
4,388

 
332

 
 
$
8,175

 
$
—

 
$
—

 
$
8,175

 
$
5,745
Fair Value Inputs, Assets, Quantitative Information [Table Text Block]
The range and weighted-average of the significant unobservable inputs used to fair value our Level 3 nonrecurring assets during 2017 and 2016, along with the valuation techniques used, are shown in the following tables:
 
 
Fair value  at
December 31, 2017
 
Valuation Technique
 
Unobservable Input
 
Range (Weighted Average) (1)
 
 
(dollars in thousands)
Impaired loans - collateral-dependent (3)
 
$
3,519

 
Fair Market Value of Collateral
 
Adjustment to Stated Value
 
N/A (2)
Impaired loans - other
 
$
3,058

 
Discounted Cash Flow
 
Discount Rate
 
3.75% - 7.75% (4.12%)
OREO
 
$
1,423

 
Fair Market Value of Collateral
 
Adjustment to Appraisal Value
 
N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of real property and a government agency guarantee.

 
 
Fair value  at
December 31, 2016
 
Valuation Technique
 
Unobservable Input
 
Range (Weighted Average) (1)
 
 
(dollars in thousands)
Impaired loans - collateral-dependent (3)
 
$
2,248

 
Fair Market Value of Collateral
 
Adjustment to Stated Value
 
N/A (2)
Impaired loans - other
 
$
1,539

 
Discounted Cash Flow
 
Discount Rate
 
4.50% - 6.50% (5.26%)
OREO
 
$
4,388

 
Fair Market Value of Collateral
 
Adjustment to Appraisal Value
 
N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of accounts receivable, inventory, equipment and real property.
Fair Value, by Balance Sheet Grouping
The following tables summarize carrying amounts and estimated fair values of selected financial instruments for the periods indicated:
 
 
December 31,
2017
 
 
Carrying
Amount
 
Fair
Value
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
 
 
Cash and due from banks
 
$
244,615

 
$
244,615

 
$
244,615

 
$
—

 
$
—

Interest-earning deposits with banks
 
97,918

 
97,918

 
97,918

 
—

 
—

Securities available for sale
 
2,742,831

 
2,742,831

 
5,328

 
2,737,503

 
—

FHLB stock
 
10,440

 
10,440

 
—

 
10,440

 
—

Loans held for sale
 
5,766

 
5,766

 
—

 
5,766

 
—

Loans
 
8,283,011

 
8,055,817

 
—

 
—

 
8,055,817

Interest rate contracts
 
6,707

 
6,707

 
—

 
6,707

 
—

Liabilities
 
 
 
 
 
 
 
 
 
 
Deposits
 
$
10,532,085

 
$
10,524,135

 
$
10,041,040

 
$
483,095

 
$
—

FHLB advances
 
11,579

 
12,281

 
—

 
12,281

 
—

Repurchase agreements
 
79,059

 
79,070

 
—

 
79,070

 
—

Subordinated debentures
 
35,647

 
35,895

 
—

 
35,895

 
—

Junior subordinated debentures
 
8,248

 
8,248

 
—

 
8,248

 
—

Interest rate contracts
 
6,714

 
6,714

 
—

 
6,714

 
—


 
 
December 31,
2016
 
 
Carrying
Amount
 
Fair
Value
 
Level 1
 
Level 2
 
Level 3
 
 
(in thousands)
Assets
 
 
 
 
 
 
 
 
 
 
Cash and due from banks
 
$
193,038

 
$
193,038

 
$
193,038

 
$
—

 
$
—

Interest-earning deposits with banks
 
31,200

 
31,200

 
31,200

 
—

 
—

Securities available for sale
 
2,278,577

 
2,278,577

 
800

 
2,277,777

 
—

FHLB stock
 
10,240

 
10,240

 
—

 
10,240

 
—

Loans held for sale
 
5,846

 
5,846

 
—

 
5,846

 
—

Loans
 
6,143,380

 
6,040,439

 
—

 
—

 
6,040,439

FDIC loss-sharing asset
 
3,535

 
867

 
—

 
—

 
867

Interest rate contracts
 
9,012

 
9,012

 
—

 
9,012

 
—

Liabilities
 
 
 
 
 
 
 
 
 
 
Deposits
 
$
8,059,415

 
$
8,055,168

 
$
7,653,122

 
$
402,046

 
$
—

FHLB advances
 
6,493

 
7,070

 
—

 
7,070

 
—

Repurchase agreements
 
80,822

 
81,131

 
—

 
81,131

 
—

Interest rate contracts
 
9,036

 
9,036

 
—

 
9,036

 
—
v3.8.0.1
Earnings Per Common Share (Tables)
 12 Months Ended
Dec. 31, 2017
Earnings Per Share [Abstract]  
Schedule of Basic and Diluted Earnings Per Share
The following table sets forth the computation of basic and diluted earnings per share for the periods indicated:
 
 
Year Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands except per share)
Basic EPS:
 
 
 
 
 
 
Net income
 
$
112,828

 
$
104,866

 
$
98,827

Less: Earnings allocated to participating securities
 
 
 
 
 
 
Preferred shares
 
3

 
185

 
175

Nonvested restricted shares
 
1,501

 
1,371

 
1,075

Earnings allocated to common shareholders
 
$
111,324

 
$
103,310

 
$
97,577

Weighted average common shares outstanding
 
59,882

 
57,184

 
57,019

Basic earnings per common share
 
$
1.86

 
$
1.81

 
$
1.71

Diluted EPS:
 
 
 
 
 
 
Earnings allocated to common shareholders
 
$
111,324

 
$
103,310

 
$
97,577

Weighted average common shares outstanding
 
59,882

 
57,184

 
57,019

Dilutive effect of equity awards and warrants
 
6

 
9

 
13

Weighted average diluted common shares outstanding
 
59,888

 
57,193

 
57,032

Diluted earnings per common share
 
$
1.86

 
$
1.81

 
$
1.71

Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive
 
13

 
19

 
37
v3.8.0.1
Share-Based Payments (Tables)
 12 Months Ended
Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Schedule of Nonvested Share Activity
A summary of changes in the Company’s nonvested shares and related information for the years ended December 31, 2017, 2016 and 2015 is presented below:
Nonvested Shares
 
Shares
 
Weighted
Average
Grant-Date
Fair Value
Nonvested at January 1, 2015
 
519,785

 
$
23.03

Granted
 
306,007

 
$
28.57

Vested
 
(131,775
)
 
$
21.55

Forfeited
 
(28,315
)
 
$
24.79

Nonvested at December 31, 2015
 
665,702

 
$
25.80

Granted
 
335,593

 
$
28.40

Vested
 
(153,235
)
 
$
23.80

Forfeited
 
(29,305
)
 
$
27.13

Nonvested at December 31, 2016
 
818,755

 
$
25.81

Granted
 
337,384

 
$
38.51

Vested
 
(253,509
)
 
$
25.67

Forfeited
 
(96,924
)
 
$
28.97

Nonvested at December 31, 2017
 
805,706

 
$
25.89
Schedule of Share-based Compensation, Stock Options, Activity
A summary of option activity under the Plan as of December 31, 2017, and changes during the year then ended is presented below:
Options
 
Shares
 
Weighted
Average
Exercise
Price
 
Weighted
Average
Remaining
Contractual
Term
 
Aggregate
Intrinsic
Value
($000)
Balance at December 31, 2016
 
23,429

 
$
45.98

 
 
 
 
Forfeited
 
(577
)
 
$
54.70

 
 
 
 
Expired
 
(2,284
)
 
$
135.97

 
 
 
 
Exercised
 
(2,242
)
 
$
10.05

 
 
 
 
Balance at December 31, 2017
 
18,326

 
$
38.88

 
0.7
 
$
214

Vested or expected to vest at December 31, 2017
 
18,326

 
$
38.88

 
0.7
 
$
214

Total Exercisable at December 31, 2017
 
18,326

 
$
38.88

 
0.7
 
$
214
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range
As of December 31, 2017, outstanding stock options consist of the following:
Ranges of
Exercise Prices
 
Number of
Option
Shares
 
Weighted Average
Remaining
Contractual Life
 
Weighted Average
Exercise Price of
Option Shares
 
Number of
Exercisable
Option Shares
 
Weighted Average
Exercise Price of
Exercisable Option
Shares
$0.00 - $9.99
 
6,393

 
1.3
 
$
9.91

 
6,393

 
$
9.91

$40.00 - $49.99
 
349

 
0.5
 
$
44.49

 
349

 
$
44.49

$50.00 - $136.93
 
11,584

 
0.3
 
$
54.70

 
11,584

 
$
54.70

 
 
18,326

 
0.7
 
$
38.88

 
18,326

 
$
38.88
v3.8.0.1
Income Tax (Tables)
 12 Months Ended
Dec. 31, 2017
Income Tax Disclosure [Abstract]  
Schedule of Components of Income Tax Expense (Benefit)
The components of income tax expense are as follows:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
(in thousands)
Current tax expense
 
$
42,724

 
$
43,069

 
$
36,426

Deferred tax expense
 
22,431

 
1,846

 
6,367

Total
 
$
65,155

 
$
44,915

 
$
42,793
Schedule of Deferred Tax Assets and Liabilities
Significant components of the Company’s deferred tax assets and liabilities are as follows:
 
 
December 31,
 
 
2017
 
2016
 
 
(in thousands)
Deferred tax assets:
 
 
 
 
Allowance for loan and lease losses
 
$
18,315

 
$
26,638

Deferred compensation
 
9,539

 
16,232

Stock options and restricted stock
 
1,438

 
1,922

OREO
 
521

 
111

Nonaccrual interest
 
163

 
320

Purchase accounting
 
—

 
2,613

Unrealized loss on investment securities
 
5,992

 
7,492

Net operating losses and credit carryforwards
 
7,259

 
8,597

Depreciation
 
—

 
1,059

Other
 
985

 
851

Total deferred tax assets
 
44,212

 
65,835

Deferred tax liabilities:
 
 
 
 
Asset purchase tax basis difference
 
(5,709
)
 
(9,037
)
FHLB stock dividends
 
(782
)
 
(1,232
)
Deferred loan fees
 
(4,505
)
 
(5,126
)
Purchase accounting
 
(9,088
)
 
—

Depreciation
 
(1,581
)
 
—

Other
 
(2,036
)
 
(155
)
Total deferred tax liabilities
 
(23,701
)
 
(15,550
)
Net deferred tax asset
 
$
20,511

 
$
50,285
Schedule of Effective Income Tax Rate Reconciliation
A reconciliation of the Company’s effective income tax rate with the federal statutory tax rate is as follows:
 
 
Years Ended December 31,
 
 
2017
 
2016
 
2015
 
 
Amount
 
Percent
 
Amount
 
Percent
 
Amount
 
Percent
 
 
(dollars in thousands)
Income tax based on statutory rate
 
$
62,262

 
35
 %
 
$
52,424

 
35
 %
 
$
49,567

 
35
 %
Reduction resulting from:
 
 
 
 
 
 
 
 
 
 
 
 
Tax exempt instruments
 
(8,485
)
 
(5
)%
 
(7,433
)
 
(5
)%
 
(6,761
)
 
(5
)%
Life insurance proceeds
 
(3,351
)
 
(2
)%
 
(1,680
)
 
(1
)%
 
(1,554
)
 
(1
)%
Acquisition costs
 
825

 
1
 %
 
—

 
—
 %
 
—

 
—
 %
Deferred tax asset revaluation
 
12,210

 
7
 %
 
—

 
—
 %
 
—

 
—
 %
Other, net
 
1,694

 
1
 %
 
1,604

 
1
 %
 
1,541

 
1
 %
Income tax provision
 
$
65,155

 
37
 %
 
$
44,915

 
30
 %
 
$
42,793

 
30
 %
v3.8.0.1
Regulatory Capital Requirements (Tables)
 12 Months Ended
Dec. 31, 2017
Regulatory Capital Requirements [Abstract]  
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations
As of December 31, 2017, the most recent notification from the Federal Deposit Insurance Corporation categorized Columbia Bank as well-capitalized under the regulatory framework for prompt corrective action. To be categorized as well- capitalized, an institution must maintain minimum CET1 risk-based, Tier 1 risk-based, total risk-based and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since the notification that management believes have changed Columbia Bank’s category.
The Company and its banking subsidiary’s actual capital amounts and ratios as of December 31, 2017 and 2016 are presented in the following table:
 
 
Actual
 
Minimum Required
For Capital
Adequacy
Purposes
 
Minimum Required
Plus Capital
Conservation Buffer
Phase-In
 
Minimum Required
Plus Capital
Conservation Buffer
Fully Phased-In
 
To Be Well
Capitalized Under
Prompt
Corrective Action
Provision
Amount
 
Ratio
 
Amount
 
Ratio
 
Amount
 
Ratio
 
Amount
 
Ratio
 
Amount
 
Ratio
 
 
(dollars in thousands)
As of December 31, 2017
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CET1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,158,252

 
11.7421
%
 
$
443,886

 
4.50
%
 
$
567,187

 
5.75
%
 
$
690,489

 
7.00
%
 
N/A

 
N/A

Columbia Bank
 
$
1,184,476

 
12.0133
%
 
$
443,687

 
4.50
%
 
$
566,933

 
5.75
%
 
$
690,180

 
7.00
%
 
$
640,881

 
6.50
%
Tier 1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,165,903

 
11.8196
%
 
$
591,848

 
6.00
%
 
$
715,149

 
7.25
%
 
$
838,451

 
8.50
%
 
N/A

 
N/A

Columbia Bank
 
$
1,184,476

 
12.0133
%
 
$
591,582

 
6.00
%
 
$
714,829

 
7.25
%
 
$
838,075

 
8.50
%
 
$
788,777

 
8.00
%
Total Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,280,326

 
12.9796
%
 
$
789,130

 
8.00
%
 
$
912,432

 
9.25
%
 
$
1,035,734

 
10.50
%
 
N/A

 
N/A

Columbia Bank
 
$
1,263,252

 
12.8123
%
 
$
788,777

 
8.00
%
 
$
912,023

 
9.25
%
 
$
1,035,269

 
10.50
%
 
$
985,971

 
10.00
%
Tier 1 Capital Leverage (to average assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
1,165,903

 
10.9611
%
 
$
425,469

 
4.00
%
 
$
425,469

 
4.00
%
 
$
425,469

 
4.00
%
 
N/A

 
N/A

Columbia Bank
 
$
1,184,476

 
10.8186
%
 
$
437,939

 
4.00
%
 
$
437,939

 
4.00
%
 
$
437,939

 
4.00
%
 
$
547,423

 
5.00
%
As of December 31, 2016
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CET1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
873,217

 
11.6450
%
 
$
337,439

 
4.50
%
 
$
384,306

 
5.125
%
 
$
524,906

 
7.00
%
 
N/A

 
N/A

Columbia Bank
 
$
862,381

 
11.5051
%
 
$
337,304

 
4.50
%
 
$
384,152

 
5.125
%
 
$
524,696

 
7.00
%
 
$
487,217

 
6.50
%
Tier 1 Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
874,688

 
11.6646
%
 
$
449,919

 
6.00
%
 
$
496,786

 
6.625
%
 
$
637,386

 
8.50
%
 
N/A

 
N/A

Columbia Bank
 
$
862,381

 
11.5051
%
 
$
449,739

 
6.00
%
 
$
496,587

 
6.625
%
 
$
637,130

 
8.50
%
 
$
599,652

 
8.00
%
Total Capital (to risk-weighted assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
947,436

 
12.6347
%
 
$
599,892

 
8.00
%
 
$
646,759

 
8.625
%
 
$
787,359

 
10.50
%
 
N/A

 
N/A

Columbia Bank
 
$
935,129

 
12.4756
%
 
$
599,652

 
8.00
%
 
$
646,500

 
8.625
%
 
$
787,043

 
10.50
%
 
$
749,565

 
10.00
%
Tier 1 Capital Leverage (to average assets):
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The Company
 
$
874,688

 
9.5526
%
 
$
366,263

 
4.00
%
 
$
366,263

 
4.00
%
 
$
366,263

 
4.00
%
 
N/A

 
N/A

Columbia Bank
 
$
862,381

 
9.4275
%
 
$
365,902

 
4.00
%
 
$
365,902

 
4.00
%
 
$
365,902

 
4.00
%
 
$
457,378

 
5.00
%
v3.8.0.1
Parent Company Financial Information (Tables)
 12 Months Ended
Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]  
Condensed Balance Sheets - Parent Company Only
Condensed Balance Sheets—Parent Company Only
 
 
December 31,
2017
 
2016 (1)
 
 
(in thousands)
Assets
 
 
 
 
Cash and due from banking subsidiary
 
$
533

 
$
1,718

Interest-earning deposits
 
8,765

 
729

Total cash and cash equivalents
 
9,298

 
2,447

Investment in banking subsidiary
 
1,971,788

 
1,238,712

Investment in other subsidiaries
 
5,157

 
4,978

Goodwill (1)
 
4,729

 
7

Other assets
 
3,426

 
5,139

Total assets
 
$
1,994,398

 
$
1,251,283

Liabilities and Shareholders’ Equity
 
 
 
 
Subordinated debentures
 
$
35,647

 
$
—

Junior subordinated debentures
 
8,248

 
—

Other liabilities
 
581

 
271

Total liabilities
 
44,476

 
271

Shareholders’ equity
 
1,949,922

 
1,251,012

Total liabilities and shareholders’ equity
 
$
1,994,398

 
$
1,251,283


_________
(1) Reclassified to conform to current period’s presentation. The reclassification was limited to adding a separate line for Goodwill, which was previously included in other assets.
Condensed Statements of Income - Parent Company Only
Condensed Statements of Income—Parent Company Only
 
 
Years Ended December 31,
2017
 
2016
 
2015
(in thousands)
Income
 
 
 
 
 
 
Dividend from banking subsidiary
 
$
66,800

 
$
83,500

 
$
67,000

Interest-earning deposits
 
2

 
4

 
5

Other income
 
8

 
8

 
92

Total income
 
66,810

 
83,512

 
67,097

Expense
 
 
 
 
 
 
Compensation and employee benefits
 
732

 
543

 
618

Subordinated debentures interest expense
 
304

 
—

 
—

Other borrowings interest expense
 
60

 
—

 
5

Other expense
 
3,090

 
1,608

 
1,368

Total expenses
 
4,186

 
2,151

 
1,991

Income before income tax benefit and equity in undistributed earnings of subsidiaries
 
62,624

 
81,361

 
65,106

Income tax benefit
 
(548
)
 
(748
)
 
(663
)
Income before equity in undistributed earnings of subsidiaries
 
63,172

 
82,109

 
65,769

Equity in undistributed earnings of subsidiaries
 
49,656

 
22,757

 
33,058

Net income
 
$
112,828

 
$
104,866

 
$
98,827
Condensed Statements of Cash Flows - Parent Company Only
Condensed Statements of Cash Flows—Parent Company Only
 
 
Years Ended December 31,
2017
 
2016
 
2015
(in thousands)
Operating Activities
 
 
 
 
 
 
Net income
 
$
112,828

 
$
104,866

 
$
98,827

Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
 
 
 
Equity in undistributed earnings of subsidiaries
 
(49,656
)
 
(22,757
)
 
(33,058
)
Stock-based compensation expense
 
7,745

 
5,009

 
4,090

Net changes in other assets and liabilities
 
1,672

 
(394
)
 
(3,170
)
Net cash provided by operating activities
 
72,589

 
86,724

 
66,689

Investing Activities
 
 
 
 
 
 
Net cash paid in business combinations
 
(580
)
 
—

 
—

Net cash provided by investing activities
 
(580
)
 
—

 
—

Financing Activities
 
 
 
 
 
 
Preferred stock dividends
 
—

 
(157
)
 
(137
)
Common stock dividends
 
(51,308
)
 
(88,677
)
 
(77,263
)
Repayment of junior subordinated debentures
 
(6,186
)
 
—

 
(8,248
)
Cash settlement of acquired equity awards
 
(7,345
)
 
—

 
—

Purchase and retirement of common stock
 
(2,299
)
 
(1,125
)
 
(906
)
Proceeds from exercise of stock options
 
1,980

 
1,349

 
1,258

Excess tax benefit associated with share-based compensation
 
—

 
344

 
—

Net cash used in financing activities
 
(65,158
)
 
(88,266
)
 
(85,296
)
Increase (decrease) in cash and cash equivalents
 
6,851

 
(1,542
)
 
(18,607
)
Cash and cash equivalents at beginning of year
 
2,447

 
3,989

 
22,596

Cash and cash equivalents at end of year
 
$
9,298

 
$
2,447

 
$
3,989

 
 
 
 
 
 
 
Supplemental disclosure of noncash investing and financing activities
 
 
 
 
 
 
Share-based consideration issued in business combinations
 
$
636,385

 
$
—

 
$
—
v3.8.0.1
Summary Of Quarterly Financial Information (Unaudited) (Tables)
 12 Months Ended
Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]  
Schedule of Quarterly Financial Information
Quarterly financial information for the years ended December 31, 2017 and 2016 is summarized as follows:
 
 
Fourth
Quarter (1)
 
Third
Quarter (2)
 
Second
Quarter
 
First
Quarter
 
Year Ended
December 31,
 
 
(in thousands, except per share amounts)
 
 
2017
 
 
 
 
 
 
 
 
 
 
Total interest income
 
$
108,841

 
$
90,303

 
$
87,786

 
$
87,816

 
$
374,746

Total interest expense
 
2,617

 
1,374

 
1,625

 
1,141

 
6,757

Net interest income
 
106,224

 
88,929

 
86,161

 
86,675

 
367,989

Provision (recapture) for loan and lease losses
 
3,327

 
(648
)
 
3,177

 
2,775

 
8,631

Noninterest income
 
23,581

 
37,067

 
24,135

 
24,859

 
109,642

Noninterest expense
 
85,627

 
67,537

 
68,867

 
68,986

 
291,017

Income before income taxes
 
40,851

 
59,107

 
38,252

 
39,773

 
177,983

Provision for income taxes
 
25,123

 
18,338

 
11,120

 
10,574

 
65,155

Net income
 
$
15,728

 
$
40,769

 
$
27,132

 
$
29,199

 
$
112,828

Per common share (3)
 
 
 
 
 
 
 
 
 
 
Earnings (basic)
 
$
0.23

 
$
0.70

 
$
0.47

 
$
0.50

 
$
1.86

Earnings (diluted)
 
$
0.23

 
$
0.70

 
$
0.47

 
$
0.50

 
$
1.86

2016
 
 
 
 
 
 
 
 
 
 
Total interest income
 
$
86,734

 
$
86,758

 
$
83,303

 
$
81,174

 
$
337,969

Total interest expense
 
997

 
1,186

 
1,163

 
1,004

 
4,350

Net interest income
 
85,737

 
85,572

 
82,140

 
80,170

 
333,619

Provision for loan and lease losses
 
18

 
1,866

 
3,640

 
5,254

 
10,778

Noninterest income
 
22,330

 
23,166

 
21,940

 
20,646

 
88,082

Noninterest expense
 
65,014

 
67,264

 
63,790

 
65,074

 
261,142

Income before income taxes
 
43,035

 
39,608

 
36,650

 
30,488

 
149,781

Provision for income taxes
 
12,317

 
12,124

 
11,245

 
9,229

 
44,915

Net income
 
$
30,718

 
$
27,484

 
$
25,405

 
$
21,259

 
$
104,866

Per common share (3)
 
 
 
 
 
 
 
 
 
 
Earnings (basic)
 
$
0.53

 
$
0.47

 
$
0.44

 
$
0.37

 
$
1.81

Earnings (diluted)
 
$
0.53

 
$
0.47

 
$
0.44

 
$
0.37

 
$
1.81

 __________
v3.8.0.1
Summary of Significant Accounting Policies (Details)
 3 Months Ended 12 Months Ended
Jun. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
location
$ / shares
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Accounting Policies [Line Items]        
FHLB membership stock purchase requirement cap   $ 10,000,000    
Gain on sale of merchant card services portfolio   $ 14,000,000 $ 0 $ 0
Number Of Branch Locations | location   155    
Number Of Days Used To Determine Treatment As Cash Equivalent   90 days    
Number of Days of Delinquency at Which Loans Are Categorized As Non Accrual Status   90 days    
Loans and Leases Receivable, Nonaccrual Loans Considered Impaired   $ 500,000    
Loans and Leases Receivable, Loans Evaluated For Impairment On Quarterly Basis, Outstanding   500,000    
Correction of immaterial error, pre-tax increase to interest income on taxable securities   1,800,000    
Federal Home Loan Bank stock, par value   100    
Correction of immaterial error, pre-tax increase to interest income on taxable securities - amount related to prior periods   $ 700,000    
Core Deposits [Member]        
Accounting Policies [Line Items]        
Estimated life of CDI, in years   10 years    
WASHINGTON        
Accounting Policies [Line Items]        
Number Of Branch Locations | location   75    
OREGON        
Accounting Policies [Line Items]        
Number Of Branch Locations | location   66    
IDAHO        
Accounting Policies [Line Items]        
Number Of Branch Locations | location   14    
Vehicles [Member]        
Accounting Policies [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives   P5Y    
Minimum [Member] | Building and Building Improvements [Member]        
Accounting Policies [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives   P5Y    
Minimum [Member] | Furniture and Fixtures [Member]        
Accounting Policies [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives   P3Y    
Minimum [Member] | Software [Member]        
Accounting Policies [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives   P3Y    
Maximum [Member] | Building and Building Improvements [Member]        
Accounting Policies [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives   P39Y    
Maximum [Member] | Furniture and Fixtures [Member]        
Accounting Policies [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives   P7Y    
Maximum [Member] | Software [Member]        
Accounting Policies [Line Items]        
Property, Plant and Equipment, Estimated Useful Lives   P5Y    
Accounting Standards Update 2018-02 [Member]        
Accounting Policies [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption   $ 0    
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member]        
Accounting Policies [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption   4,082,000    
Accounting Standards Update 2016-09 [Member]        
Accounting Policies [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption     67,000  
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income   $ 1,300,000    
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share | $ / shares   $ 0.02    
Accounting Standards Update 2016-09 [Member] | Retained Earnings [Member]        
Accounting Policies [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption     (117,000)  
Accounting Standards Update 2016-09 [Member] | Common Stock [Member]        
Accounting Policies [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption     184,000  
Accounting Standards Update 2016-01 [Member]        
Accounting Policies [Line Items]        
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income   $ 3,000 $ 33,000 $ 64,000
Merchant Card Services Agreement [Member]        
Accounting Policies [Line Items]        
Gain on sale of merchant card services portfolio   14,000,000    
Net carrying amount of merchant card services portfolio upon sale $ 0      
Net revenue share - merchant card services   $ 1,100,000    
v3.8.0.1
Business Combinations (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Nov. 01, 2017
Dec. 31, 2017
Dec. 31, 2016
Business Acquisition [Line Items]      
Junior Subordinated Notes   $ 8,248 $ 0
Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Cost of Acquired Entity, Purchase Price, Total $ 637,103    
Business Combination, Acquisition Related Costs   17,196 291
Business Acquisition, Effective Date of Acquisition Nov. 01, 2017    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents $ 81,190    
Business Acquisition, Purchase Price Allocation, Current Assets, Marketable Securities 449,291    
Business Acquisition, Purchase Price Allocation, FHLB Stock 7,084    
Business Combination, Acquired Receivable, Fair Value 1,873,987    
Business Acquisition, Purchase Price Allocation, Accrued Interest Receivable 7,827    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment 27,343    
Business Acquisition, Purchase Price Allocation, Other Real Estate Owned 10,279    
Business Combination, Purchase Price Allocation, Amortizable Intangible Assets 46,875    
Business Combination, Purchase Price Allocation, Other Assets 50,638    
Business Acquisition, Purchase Price Allocation, Liabilities, Deposits (2,118,982)    
Business Combination, Purchase Price Allocation, Federal Home Loan bank advances 101,127    
Business Combination, Purchase Price Allocation, Subordinated Debt (35,678)    
Business combination, purchase price allocation, securities sold under agreements to repurchase (1,617)    
Business Acquisition, Purchase Price Allocation, Other Noncurrent Liabilities (28,653)    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net 254,023    
Business Combination, Purchase Price Allocation, Goodwill Amount $ 383,080    
Business Acquisition, Pro Forma Revenue   571,944 520,419
Business Acquisition, Pro Forma Net Income (Loss)   $ 149,859 $ 124,550
Business Acquisition, Pro Forma Earnings Per Share, Basic   $ 2.23 $ 1.86
Business Acquisition, Pro Forma Earnings Per Share, Diluted   $ 2.23 $ 1.86
Compensation and employee benefits [Member] | Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Acquisition Related Costs   $ 8,014 $ 0
Occupancy [Member] | Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Acquisition Related Costs   1,912 0
Advertising and promotion [Member] | Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Acquisition Related Costs   467 0
Data processing and communications [Member] | Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Acquisition Related Costs   1,555 0
Legal and professional fees [Member] | Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Acquisition Related Costs   4,618 291
Taxes, licenses and fees [Member] | Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Acquisition Related Costs   10 0
Other noninterest expenses [Member] | Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Acquisition Related Costs   $ 620 $ 0
v3.8.0.1
Business Combinations narrative (Details) - USD ($)
$ in Thousands
 12 Months Ended
Nov. 01, 2017
Dec. 31, 2017
Dec. 31, 2016
Business Acquisition [Line Items]      
Threshold for average assets requiring CFPB examination   $ 10,000,000  
Estimated pre-tax annual impact of no longer qualifying for the small issuer exemption from interchange fee cap   10,000  
Pacific Continental [Member]      
Business Acquisition [Line Items]      
Business Combination, Purchase Price Allocation, Junior Subordinated Debentures $ (14,434)    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities (2,300,491)    
Business Combination, Purchase Price Allocation, Goodwill Amount $ 383,080    
Business Acquisition, Effective Date of Acquisition Nov. 01, 2017    
Business Combination, Cost of Acquired Entity, Purchase Price, Total $ 637,103    
Business Combination, Acquired Receivable, Fair Value 1,873,987    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net 254,023    
Business Combination, Purchase Price Allocation, Amortizable Intangible Assets $ 46,875    
business combinations, core deposit intangible percentage of core deposits 2.34%    
Business Combination, Acquisition Related Costs   $ 17,196 $ 291
Business Combination, Purchase Price Allocation, Other Assets $ 50,638    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets 2,554,514    
Business Acquisition, Purchase Price Allocation, Liabilities, Deposits $ 2,118,982    
Business Acquisition, Percentage of Voting Interests Acquired 100.00%    
Business Combination, Purchase Price Allocation, Federal Home Loan bank advances $ (101,127)    
v3.8.0.1
Cash and Cash Equivalents (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Federal Reserve Bank [Member]    
Restricted Cash and Cash Equivalents Items [Line Items]    
Restricted Cash and Cash Equivalents $ 76.5 $ 62.8
v3.8.0.1
Securities (Securities Available for Sale) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost $ 2,768,605 $ 2,299,037  
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 8,564 10,231  
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (34,338) (30,691)  
Securities available for sale 2,742,831 2,278,577  
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]      
Available-for-sale Securities, Gross Realized Losses 122 0 $ 10
Available-for-sale Securities, Gross Realized Gains 111 1,181 $ 1,591
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 1,752,236 1,486,690  
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 1,815 2,760  
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (27,326) (23,718)  
Securities available for sale 1,726,725 1,465,732  
State and Municipal Securities [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 593,940 473,914  
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 6,023 6,343  
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (3,959) (5,197)  
Securities available for sale 596,004 475,060  
U.S. Government Agency and Government-Sponsored Enterprise Securities [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 416,894 332,348  
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 642 1,065  
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (2,762) (1,511)  
Securities available for sale 414,774 331,902  
US Treasury Securities [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 251 801  
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 0 0  
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (3) (1)  
Securities available for sale 248 800  
Other Securities [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 5,284 5,284  
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 84 63  
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax (288) (264)  
Securities available for sale $ 5,080 $ 5,083  
v3.8.0.1
Securities (Schedule of Contractual Maturities of Investment Securities Available for Sale) (Details)
$ in Thousands
Dec. 31, 2017
USD ($)
Available-for-sale Securities [Abstract]  
Due within one year, Amortized Cost $ 124,885
Due after one year through five years, Amortized Cost 638,921
Due after five years through ten years, Amortized Cost 804,462
Due after ten years, Amortized Cost 1,195,053
Total investment securities available-for-sale, Amortized Cost 2,768,605
Due within one year, Fair Value 124,763
Due after one year through five years, Fair Value 636,860
Due after five years through ten years, Fair Value 796,611
Due after ten years, Fair Value 1,179,517
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis 5,284
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value 5,080
Total investment securities available-for-sale, Fair Value $ 2,742,831
v3.8.0.1
Securities (Carrying Value of Securities Pledged as Collateral) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Carrying amount of securities pledged as collateral $ 419,383 $ 398,889
To Washington and Oregon State To Secure Public Deposits [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Carrying amount of securities pledged as collateral 245,222 232,714
To Federal Reserve Bank To Secure Borrowings [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Carrying amount of securities pledged as collateral 52,917 33,825
Other Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Carrying amount of securities pledged as collateral $ 121,244 $ 132,350
v3.8.0.1
Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 Months Fair Value $ 1,220,992 $ 1,461,783
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant 9,442 25,415
12 Months or More Fair Value 953,348 165,173
12 Months or More Unrealized Losses (24,896) (5,276)
Total Fair Value 2,174,340 1,626,956
Total Unrealized Losses (34,338) (30,691)
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 Months Fair Value 816,678 1,029,116
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant 6,710 18,788
12 Months or More Fair Value 717,211 159,046
12 Months or More Unrealized Losses (20,616) (4,930)
Total Fair Value 1,533,889 1,188,162
Total Unrealized Losses (27,326) (23,718)
State and Municipal Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 Months Fair Value 220,019 211,342
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant 1,723 5,064
12 Months or More Fair Value 75,172 3,384
12 Months or More Unrealized Losses (2,236) (133)
Total Fair Value 295,191 214,726
Total Unrealized Losses (3,959) (5,197)
U.S. Government Agency and Government-Sponsored Enterprise Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 Months Fair Value 184,046 218,811
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant 1,006 1,511
12 Months or More Fair Value 155,983 0
12 Months or More Unrealized Losses (1,756) 0
Total Fair Value 340,029 218,811
Total Unrealized Losses (2,762) (1,511)
US Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 Months Fair Value 249 251
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant 3 1
12 Months or More Fair Value 0 0
12 Months or More Unrealized Losses 0 0
Total Fair Value 249 251
Total Unrealized Losses (3) (1)
Other Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 Months Fair Value 0 2,263
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss, Instant 0 51
12 Months or More Fair Value 4,982 2,743
12 Months or More Unrealized Losses (288) (213)
Total Fair Value 4,982 5,006
Total Unrealized Losses $ (288) $ (264)
v3.8.0.1
Securities (Narrative) (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
USD ($)
issuance
security
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Schedule of Available-for-sale Securities [Line Items]      
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds | $ $ 30,403 $ 124,142 $ 95,375
Number Of Issuances Of Securities Exceeding Shareholders Equity Threshold | issuance 0    
US Treasury Securities [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Number Of Securities In Unrealized Loss Position 1    
Number Of Securities In Continuous Loss Position For Twelve Months or More 0    
Other Securities [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Issuances Of Securities Exceeding Shareholders Equity Threshold, Percent 10.00%    
Number Of Securities In Unrealized Loss Position 2    
Number Of Securities In Continuous Loss Position For Twelve Months or More 2    
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Number Of Securities In Unrealized Loss Position 396    
Number Of Securities In Continuous Loss Position For Twelve Months or More 120    
Municipal Bonds [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Number Of Securities In Unrealized Loss Position 314    
Number Of Securities In Continuous Loss Position For Twelve Months or More 69    
US Government Corporations and Agencies Securities [Member]      
Schedule of Available-for-sale Securities [Line Items]      
Number Of Securities In Unrealized Loss Position 44    
Number Of Securities In Continuous Loss Position For Twelve Months or More 16    
v3.8.0.1
Securities Securities (Summary of Gross Realized Gains and Losses) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]      
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds $ 30,403 $ 124,142 $ 95,375
Available-for-sale Securities, Gross Realized Gains 111 1,181 1,591
Available-for-sale Securities, Gross Realized Losses (122) 0 (10)
Gain (Loss) on Sale of Securities, Net $ (11) $ 1,181 $ 1,581
v3.8.0.1
Loans (Narrative) (Details)
$ in Thousands, loan in Millions
 12 Months Ended
Dec. 31, 2017
USD ($)
contract
Dec. 31, 2016
USD ($)
loan
contract
Dec. 31, 2015
USD ($)
contract
Financing Receivable, Recorded Investment [Line Items]      
Loans to related parties $ 10,000 $ 10,100  
Loans and Leases Receivable, Related Parties, Additions 203    
Repayments on related party loans 350    
Financing Receivable, Recorded Investment, Nonaccrual Status 66,189    
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans 2,400 $ 1,900 $ 1,300
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans 581    
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans | loan   0.0  
Loans and Leases Receivable, Nonaccrual of Interest, Commitments of Additional Funds 2,000 $ 293  
Financing Receivable Modifications Additional Commitment To Lend $ 506 $ 508  
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | contract 0 0 0
Loans Receivable [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans pledged to collateralize Federal Home Loan Bank Advances $ 2,250,000 $ 2,290,000  
Commercial Loan [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans pledged to collateralize Federal Reserve Bank Borrowings $ 70,200 $ 54,200  
v3.8.0.1
Loans (Analysis of Loan Portfolio by Major Types of Loans) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]        
Less: Net unearned income $ (52,111) $ (33,718)    
Total loans, net of unearned income 8,358,657 6,213,423    
Less: Allowance for loan and lease losses (75,646) (70,043) $ (68,172) $ (69,569)
Loans, net 8,283,011 6,143,380    
Loans held for sale 5,766 5,846    
Real estate: One-to-four family residential [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Real Estate 200,791 188,193    
Real Estate Construction 200,695 122,719    
Less: Allowance for loan and lease losses (701) (599) (916) (2,281)
Commercial and Multifamily Residential [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Real Estate 3,901,333 2,809,061    
Real Estate Construction 372,538 210,683    
Commercial Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Commercial Business 3,389,952 2,571,239    
Real Estate Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Total Real Estate 4,102,124 2,997,254    
Real Estate Construction Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Total Real Estate Construction 573,233 333,402    
Consumer [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Consumer, Other 345,459 345,246    
Less: Allowance for loan and lease losses (5,163) (3,534) $ (3,531) $ (3,180)
Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Less: Net unearned income (52,111) (33,718)    
Total loans, net of unearned income 8,245,987 6,067,763    
Less: Allowance for loan and lease losses (68,739) (59,528)    
Loans, net 8,177,248 6,008,235    
Loans held for sale 5,766 5,846    
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Real Estate 188,396 170,331    
Real Estate Construction 200,518 121,887    
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial and Multifamily Residential [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Real Estate 3,825,739 2,719,830    
Real Estate Construction 371,931 209,118    
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Commercial Business 3,377,324 2,551,054    
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real Estate Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Total Real Estate 4,014,135 2,890,161    
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real Estate Construction Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Total Real Estate Construction 572,449 331,005    
Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Consumer, Other 334,190 329,261    
Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Less: Net unearned income 0 0    
Total loans, net of unearned income 112,670 145,660    
Less: Allowance for loan and lease losses (6,907) (10,515)    
Loans, net 105,763 135,145    
Loans held for sale 0 0    
Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Real Estate 12,395 17,862    
Real Estate Construction 177 832    
Purchased Credit Impaired Loans [Member] | Commercial and Multifamily Residential [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Real Estate 75,594 89,231    
Real Estate Construction 607 1,565    
Purchased Credit Impaired Loans [Member] | Commercial Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Commercial Business 12,628 20,185    
Purchased Credit Impaired Loans [Member] | Real Estate Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Total Real Estate 87,989 107,093    
Purchased Credit Impaired Loans [Member] | Real Estate Construction Portfolio Segment [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Total Real Estate Construction 784 2,397    
Purchased Credit Impaired Loans [Member] | Consumer [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Consumer, Other $ 11,269 $ 15,985    
v3.8.0.1
Loans (Analysis of Nonaccrual Loans) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status $ 66,189  
Unpaid Principal Balance Nonaccrual Loans 79,886 $ 42,289
Recorded Investment Nonaccrual Loans   27,756
Consumer [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 4,149  
Unpaid Principal Balance Nonaccrual Loans 4,633 4,331
Recorded Investment Nonaccrual Loans   3,883
Commercial business: Secured loans [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 45,410  
Unpaid Principal Balance Nonaccrual Loans 56,865 21,503
Recorded Investment Nonaccrual Loans   11,524
Commercial business: Unsecured loans [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 50  
Unpaid Principal Balance Nonaccrual Loans 49 303
Recorded Investment Nonaccrual Loans   31
Real estate: One-to-four family residential [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 785  
Unpaid Principal Balance Nonaccrual Loans 1,182 1,302
Recorded Investment Nonaccrual Loans   568
Real estate: Commercial and multifamily residential: Commercial land [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 2,628  
Unpaid Principal Balance Nonaccrual Loans 2,623 922
Recorded Investment Nonaccrual Loans   934
Real estate: Commercial and multifamiIy residential: Income property [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 4,284  
Unpaid Principal Balance Nonaccrual Loans 5,410 4,247
Recorded Investment Nonaccrual Loans   4,005
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 7,029  
Unpaid Principal Balance Nonaccrual Loans 7,270 9,030
Recorded Investment Nonaccrual Loans   6,248
Real estate construction: One-to-four family residential: Land and acquisition [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 25  
Unpaid Principal Balance Nonaccrual Loans 26 102
Recorded Investment Nonaccrual Loans   14
Real estate construction: One-to-four family residential: Residential construction [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable, Recorded Investment, Nonaccrual Status 1,829  
Unpaid Principal Balance Nonaccrual Loans $ 1,828 549
Recorded Investment Nonaccrual Loans   $ 549
v3.8.0.1
Loans (Analysis of the Aged Loan Portfolio) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans $ 66,189  
Consumer [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 4,149  
Commercial business: Secured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 45,410  
Commercial business: Unsecured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 50  
Real estate: One-to-four family residential [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 785  
Real estate: Commercial and multifamily residential: Commercial land [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 2,628  
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 7,029  
Real estate construction: One-to-four family residential: Land and acquisition [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 25  
Real estate construction: One-to-four family residential: Residential construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 1,829  
Real estate: Commercial and multifamiIy residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Nonaccrual Loans 4,284  
Loans, Excluding Purchased Credit Impaired Loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 8,163,583 $ 6,031,078
Total Past Due 16,215 8,929
Nonaccrual Loans 66,189 27,756
Loans Receivable, Net 8,245,987 6,067,763
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 293,028 103,779
Total Past Due 0 0
Nonaccrual Loans 0 0
Loans Receivable, Net 293,028 103,779
Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 325,928 318,369
Total Past Due 2,148 2,270
Nonaccrual Loans 4,149 3,883
Loans Receivable, Net 332,225 324,522
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 3,185,321 2,439,250
Total Past Due 4,930 816
Nonaccrual Loans 45,410 11,524
Loans Receivable, Net 3,235,661 2,451,590
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 123,524 94,118
Total Past Due 601 588
Nonaccrual Loans 50 31
Loans Receivable, Net 124,175 94,737
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 184,256 164,416
Total Past Due 1,513 2,948
Nonaccrual Loans 785 568
Loans Receivable, Net 186,554 167,932
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 292,680 269,816
Total Past Due 673 64
Nonaccrual Loans 2,628 934
Loans Receivable, Net 295,981 270,814
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 1,590,004 1,052,078
Total Past Due 2,953 1,652
Nonaccrual Loans 7,029 6,248
Loans Receivable, Net 1,599,986 1,059,978
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 9,882 11,542
Total Past Due 0 0
Nonaccrual Loans 25 14
Loans Receivable, Net 9,907 11,556
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 187,862 109,080
Total Past Due 0 0
Nonaccrual Loans 1,829 549
Loans Receivable, Net 189,691 109,629
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 1,898,655 1,365,150
Total Past Due 3,397 591
Nonaccrual Loans 4,284 4,005
Loans Receivable, Net 1,906,336 1,369,746
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Current Loans 72,443 103,480
Total Past Due 0 0
Nonaccrual Loans 0 0
Loans Receivable, Net 72,443 103,480
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 10,190 7,772
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 1,446 2,035
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 2,530 806
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 100 287
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 1,111 2,448
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 92 64
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 2,485 1,652
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 2,426 480
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 5,444 1,157
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 702 235
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 2,400 10
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 501 301
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 402 500
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 468 0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 971 111
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 581 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 581 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due 0 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]    
Financing Receivable, Recorded Investment, Past Due [Line Items]    
Total Past Due $ 0 $ 0
v3.8.0.1
Loans (Analysis of Impaired Loans) (Details) - Loans, Excluding Purchased Credit Impaired Loans [Member]
$ in Thousands
 12 Months Ended
Dec. 31, 2017
USD ($)
Modifications
Dec. 31, 2016
USD ($)
Modifications
Dec. 31, 2015
USD ($)
Modifications
Financing Receivable, Modifications, Number of Contracts | Modifications 60 54 7
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 8,176,782 $ 6,042,304  
Recorded Investment of Loans Individually Measured for Specific Impairment 69,205 25,459  
Recorded Investment 5,303 4,464  
Unpaid Principal Balance 5,568 4,558  
Related Allowance 199 57  
Impaired Financing Receivable, Average Recorded Investment 40,650 21,493 $ 22,372
Impaired Financing Receivable, Interest Income, Accrual Method $ 971 $ 237 $ 202
Commercial business: Secured loans [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 10 9 5
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 3,195,649 $ 2,442,772  
Recorded Investment of Loans Individually Measured for Specific Impairment 40,012 8,818  
Recorded Investment 3,808 2,414  
Unpaid Principal Balance 3,937 2,484  
Related Allowance 1,867 664  
Impaired Financing Receivable, Average Recorded Investment 20,282 9,368 $ 7,987
Impaired Financing Receivable, Interest Income, Accrual Method $ 60 $ 79 $ 84
Commercial business: Unsecured loans [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 124,150 $ 94,737  
Recorded Investment of Loans Individually Measured for Specific Impairment 25 0  
Recorded Investment 25 0  
Unpaid Principal Balance 24 0  
Related Allowance 3 0  
Impaired Financing Receivable, Average Recorded Investment 5 0 $ 0
Impaired Financing Receivable, Interest Income, Accrual Method $ 0 $ 0 $ 0
Real estate: One-to-four family residential [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 3 3 1
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 185,659 $ 167,403  
Recorded Investment of Loans Individually Measured for Specific Impairment 895 529  
Recorded Investment 867 435  
Unpaid Principal Balance 1,408 693  
Related Allowance 103 12  
Impaired Financing Receivable, Average Recorded Investment 730 743 $ 2,848
Impaired Financing Receivable, Interest Income, Accrual Method $ 49 $ 10 $ 47
Real estate: Commercial and multifamily residential: Commercial land [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 293,694 $ 270,106  
Recorded Investment of Loans Individually Measured for Specific Impairment 2,287 708  
Recorded Investment 0 0  
Unpaid Principal Balance 0 0  
Related Allowance 0 0  
Impaired Financing Receivable, Average Recorded Investment 2,079 425 $ 94
Impaired Financing Receivable, Interest Income, Accrual Method $ 0 $ 0 $ 0
Real estate: Commercial and multifamiIy residential: Income property [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 1,901,313 $ 1,365,321  
Recorded Investment of Loans Individually Measured for Specific Impairment 5,023 4,425  
Recorded Investment 2,768 540  
Unpaid Principal Balance 3,328 544  
Related Allowance 185 27  
Impaired Financing Receivable, Average Recorded Investment 4,314 2,492 $ 2,913
Impaired Financing Receivable, Interest Income, Accrual Method $ 51 $ 26 $ 36
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 1 0
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 1,591,298 $ 1,054,564  
Recorded Investment of Loans Individually Measured for Specific Impairment 8,688 5,414  
Recorded Investment 77 0  
Unpaid Principal Balance 80 0  
Related Allowance 3 0  
Impaired Financing Receivable, Average Recorded Investment 5,335 5,084 $ 7,052
Impaired Financing Receivable, Interest Income, Accrual Method 445 0 26
Real estate construction: One-to-four family residential: Land and acquisition [Member]      
Recorded Investment of Loans Collectively Measured for Contingency Provision 9,907 11,542  
Recorded Investment of Loans Individually Measured for Specific Impairment 0 14  
Recorded Investment 0 14  
Unpaid Principal Balance 0 102  
Related Allowance 0 1  
Impaired Financing Receivable, Average Recorded Investment 3 199 641
Impaired Financing Receivable, Interest Income, Accrual Method 0 0 5
Real estate construction: One-to-four family residential: Residential construction [Member]      
Recorded Investment of Loans Collectively Measured for Contingency Provision 188,481 109,293  
Recorded Investment of Loans Individually Measured for Specific Impairment 1,210 336  
Recorded Investment 0 0  
Unpaid Principal Balance 0 0  
Related Allowance 0 0  
Impaired Financing Receivable, Average Recorded Investment 309 472 648
Impaired Financing Receivable, Interest Income, Accrual Method 0 0 $ 0
Real estate construction: Commercial and multifamily residential: Income property [Member]      
Recorded Investment of Loans Collectively Measured for Contingency Provision 293,028 103,779  
Recorded Investment of Loans Individually Measured for Specific Impairment 0 0  
Recorded Investment 0 0  
Unpaid Principal Balance 0 0  
Related Allowance $ 0 $ 0  
Real estate construction: Commercial and multifamily residential: Owner occupied [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 68,393 $ 103,480  
Recorded Investment of Loans Individually Measured for Specific Impairment 4,050 0  
Recorded Investment 0 0  
Unpaid Principal Balance 0 0  
Related Allowance 0 0  
Impaired Financing Receivable, Average Recorded Investment 1,620 0 $ 0
Impaired Financing Receivable, Interest Income, Accrual Method $ 203 $ 0 $ 0
Consumer [Member]      
Financing Receivable, Modifications, Number of Contracts | Modifications 42 41 1
Recorded Investment of Loans Collectively Measured for Contingency Provision $ 325,210 $ 319,307  
Recorded Investment of Loans Individually Measured for Specific Impairment 7,015 5,215  
Impaired Financing Receivable, Average Recorded Investment 5,973 2,710 $ 189
Impaired Financing Receivable, Interest Income, Accrual Method 163 122 $ 4
Impaired Loans Without Recorded Allowance [Member]      
Recorded Investment 56,357 17,592  
Unpaid Principal Balance 64,735 27,228  
Impaired Loans With Recorded Allowance [Member]      
Recorded Investment 12,848 7,867  
Unpaid Principal Balance 14,345 8,381  
Related Allowance 2,360 761  
Impaired Loans Without Recorded Allowance [Member]      
Recorded Investment 1,712 751  
Unpaid Principal Balance 1,864 833  
Impaired Loans Without Recorded Allowance [Member] | Commercial business: Secured loans [Member]      
Recorded Investment 36,204 6,404  
Unpaid Principal Balance 42,314 12,831  
Impaired Loans Without Recorded Allowance [Member] | Commercial business: Unsecured loans [Member]      
Recorded Investment 0 0  
Unpaid Principal Balance 0 0  
Impaired Loans Without Recorded Allowance [Member] | Real estate: One-to-four family residential [Member]      
Recorded Investment 28 94  
Unpaid Principal Balance 337 291  
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]      
Recorded Investment 2,287 708  
Unpaid Principal Balance 2,282 687  
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]      
Recorded Investment 2,255 3,885  
Unpaid Principal Balance 2,601 4,148  
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]      
Recorded Investment 8,611 5,414  
Unpaid Principal Balance 10,077 8,102  
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]      
Recorded Investment 0 0  
Unpaid Principal Balance 0 0  
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]      
Recorded Investment 1,210 336  
Unpaid Principal Balance 1,210 336  
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]      
Recorded Investment 0 0  
Unpaid Principal Balance 0 0  
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]      
Recorded Investment 4,050 0  
Unpaid Principal Balance $ 4,050 $ 0  
v3.8.0.1
Loans Loans (Analysis of Troubled Debt Restructurings) (Details)
loan in Millions
 12 Months Ended
Dec. 31, 2017
USD ($)
Modifications
contract
Dec. 31, 2016
USD ($)
loan
Modifications
contract
Dec. 31, 2015
USD ($)
Modifications
contract
Financing Receivable, Modifications [Line Items]      
Financing Receivable Modifications Additional Commitment To Lend $ 506,000 $ 508,000  
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | contract 0 0 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment $ 0 $ 0 $ 0
FHLB Advances, Collateral Pledged $ 1,443,554,000 $ 1,510,514,000  
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing, Number of Loans | loan   0.0  
Loans, Excluding Purchased Credit Impaired Loans [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 60 54 7
Pre-Modification Outstanding Recorded Investment $ 18,122,000 $ 7,679,000 $ 3,808,000
Post-Modification Outstanding Recorded Investment $ 18,122,000 $ 7,677,000 $ 3,790,000
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 10 9 5
Pre-Modification Outstanding Recorded Investment $ 5,655,000 $ 2,131,000 $ 3,724,000
Post-Modification Outstanding Recorded Investment $ 5,655,000 $ 2,131,000 $ 3,706,000
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Pre-Modification Outstanding Recorded Investment $ 26,000 $ 0 $ 0
Post-Modification Outstanding Recorded Investment $ 26,000 $ 0 $ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 3 3 1
Pre-Modification Outstanding Recorded Investment $ 583,000 $ 203,000 $ 30,000
Post-Modification Outstanding Recorded Investment $ 583,000 $ 203,000 $ 30,000
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Pre-Modification Outstanding Recorded Investment $ 687,000 $ 0 $ 0
Post-Modification Outstanding Recorded Investment $ 687,000 $ 0 $ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Pre-Modification Outstanding Recorded Investment $ 1,152,000 $ 0 $ 0
Post-Modification Outstanding Recorded Investment $ 1,152,000 $ 0 $ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 1 0
Pre-Modification Outstanding Recorded Investment $ 78,000 $ 250,000 $ 0
Post-Modification Outstanding Recorded Investment $ 78,000 $ 250,000 $ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 1 0 0
Pre-Modification Outstanding Recorded Investment $ 4,050,000 $ 0 $ 0
Post-Modification Outstanding Recorded Investment $ 4,050,000 $ 0 $ 0
Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]      
Financing Receivable, Modifications [Line Items]      
Financing Receivable, Modifications, Number of Contracts | Modifications 42 41 1
Pre-Modification Outstanding Recorded Investment $ 5,891,000 $ 5,095,000 $ 54,000
Post-Modification Outstanding Recorded Investment $ 5,891,000 $ 5,093,000 $ 54,000
v3.8.0.1
Loans Loans, analysis of purchased credit impaired loans (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Allowance $ 75,646 $ 70,043 $ 68,172 $ 69,569
Loans and Leases Receivable, Net Amount 8,283,011 6,143,380    
Real estate: One-to-four family residential [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Allowance 701 599 916 2,281
Consumer [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Allowance 5,163 3,534 $ 3,531 $ 3,180
Purchased Credit Impaired Loans [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 120,758 157,251    
Valuation discount resulting from acquisition accounting 8,088 11,591    
Loans and Leases Receivable, Allowance 6,907 10,515    
Loans and Leases Receivable, Net Amount 105,763 135,145    
Purchased Credit Impaired Loans [Member] | Commercial Portfolio Segment [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 13,753 21,606    
Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 14,610 20,643    
Purchased Credit Impaired Loans [Member] | Commercial and Multifamily Residential [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 79,211 94,795    
Purchased Credit Impaired Loans [Member] | Real Estate Portfolio Segment [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 93,821 115,438    
Purchased Credit Impaired Loans [Member] | One-to-Four Family Residential Construction [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 177 832    
Purchased Credit Impaired Loans [Member] | Commercial and Multifamily Residential Construction [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 595 1,726    
Purchased Credit Impaired Loans [Member] | Real Estate Construction Portfolio Segment [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 772 2,558    
Purchased Credit Impaired Loans [Member] | Consumer [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount $ 12,412 $ 17,649    
v3.8.0.1
Loans Loans (Analysis of Purchased Credit Impaired - Accretable Yield Rollforward) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Loans, Analysis of Purchased Credit Impaired Loans, Accretable Yield Rollforward [Abstract]        
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield $ 31,176 $ 45,191 $ 58,981 $ 73,849
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion (12,357) (16,266) (21,919)  
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans 158 148 1,681  
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference $ (1,500) $ 2,624 $ 8,732  
v3.8.0.1
Allowance for Loan and Lease Losses and Unfunded Commitments and Letters of Credit (Allowance for Noncovered Loan and Lease Losses) (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       $ 70,043       $ 68,172 $ 70,043 $ 68,172 $ 69,569
Charge-offs                 (16,660) (21,462) (25,067)
Recoveries                 13,632 12,555 15,079
Provision for loan and lease losses $ 3,327 [1] $ (648) $ 3,177 2,775 $ 18 $ 1,866 $ 3,640 5,254 8,631 10,778 8,591
Balance at the end of year 75,646       70,043       75,646 70,043 68,172
Specific Reserve 2,360       761       2,360 761 653
General Allocation 73,286       69,282       73,286 69,282 67,519
Consumer [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       3,534       3,531 3,534 3,531 3,180
Charge-offs                 (1,474) (1,238) (2,066)
Recoveries                 1,187 933 931
Provision for loan and lease losses                 1,916 308 1,486
Balance at the end of year 5,163       3,534       5,163 3,534 3,531
Specific Reserve 199       57       199 57 15
General Allocation 4,964       3,477       4,964 3,477 3,516
Purchased Credit Impaired Loans [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       10,515       13,726 10,515 13,726 16,336
Charge-offs                 (6,812) (9,944) (13,854)
Recoveries                 6,187 7,004 7,329
Provision for loan and lease losses                 (2,983) (271) 3,915
Balance at the end of year 6,907       10,515       6,907 10,515 13,726
Specific Reserve 0       0       0 0 0
General Allocation 6,907       10,515       6,907 10,515 13,726
Unallocated Financing Receivables [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       226       569 226 569 1,844
Charge-offs                 0 0 0
Recoveries                 0 0 0
Provision for loan and lease losses                 (226) (343) (1,275)
Balance at the end of year 0       226       0 226 569
Specific Reserve 0       0       0 0 0
General Allocation 0       226       0 226 569
Commercial business: Secured loans [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       36,050       32,321 36,050 32,321 25,923
Charge-offs                 (7,524) (9,993) (7,486)
Recoveries                 4,283 2,483 2,069
Provision for loan and lease losses                 (3,468) 11,239 11,815
Balance at the end of year 29,341       36,050       29,341 36,050 32,321
Specific Reserve 1,867       664       1,867 664 321
General Allocation 27,474       35,386       27,474 35,386 32,000
Commercial business: Unsecured loans [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       960       1,299 960 1,299 927
Charge-offs                 (89) (75) (780)
Recoveries                 553 162 267
Provision for loan and lease losses                 576 (426) 885
Balance at the end of year 2,000       960       2,000 960 1,299
Specific Reserve 3       0       3 0 0
General Allocation 1,997       960       1,997 960 1,299
Real estate: One-to-four family residential [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       599       916 599 916 2,281
Charge-offs                 (460) (35) (376)
Recoveries                 568 171 307
Provision for loan and lease losses                 (6) (453) (1,296)
Balance at the end of year 701       599       701 599 916
Specific Reserve 103       12       103 12 314
General Allocation 598       587       598 587 602
Real estate: Commercial and multifamily residential: Commercial land [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       1,797       1,178 1,797 1,178 799
Charge-offs                 0 (26) 0
Recoveries                 53 2 291
Provision for loan and lease losses                 2,415 643 88
Balance at the end of year 4,265       1,797       4,265 1,797 1,178
Specific Reserve 0       0       0 0 0
General Allocation 4,265       1,797       4,265 1,797 1,178
Real estate: Commercial and multifamiIy residential: Income property [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       7,342       6,616 7,342 6,616 9,159
Charge-offs                 (287) 0 (390)
Recoveries                 498 966 3,568
Provision for loan and lease losses                 (1,881) (240) (5,721)
Balance at the end of year 5,672       7,342       5,672 7,342 6,616
Specific Reserve 185       27       185 27 0
General Allocation 5,487       7,315       5,487 7,315 6,616
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       6,439       5,550 6,439 5,550 5,007
Charge-offs                 0 (63) (115)
Recoveries                 124 434 116
Provision for loan and lease losses                 (1,104) 518 542
Balance at the end of year 5,459       6,439       5,459 6,439 5,550
Specific Reserve 3       0       3 0 0
General Allocation 5,456       6,439       5,456 6,439 5,550
Real estate construction: One-to-four family residential: Land and acquisition [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       316       339 316 339 1,197
Charge-offs                 (14) (88) 0
Recoveries                 72 57 103
Provision for loan and lease losses                 589 8 (961)
Balance at the end of year 963       316       963 316 339
Specific Reserve 0       1       0 1 0
General Allocation 963       315       963 315 339
Real estate construction: One-to-four family residential: Residential construction [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       669       733 669 733 1,860
Charge-offs                 0 0 0
Recoveries                 106 234 90
Provision for loan and lease losses                 2,934 (298) (1,217)
Balance at the end of year 3,709       669       3,709 669 733
Specific Reserve 0       0       0 0 3
General Allocation 3,709       669       3,709 669 730
Real estate construction: Commercial and multifamily residential: Income property [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       404       388 404 388 622
Charge-offs                 0 0 0
Recoveries                 1 109 8
Provision for loan and lease losses                 6,648 (93) (242)
Balance at the end of year 7,053       404       7,053 404 388
Specific Reserve 0       0       0 0 0
General Allocation 7,053       404       7,053 404 388
Real estate construction: Commercial and multifamily residential: Owner occupied [Member]                      
Allowance for Loan and Lease Losses [Roll Forward]                      
Balance at beginning of year       $ 1,192       $ 1,006 1,192 1,006 434
Charge-offs                 0 0 0
Recoveries                 0 0 0
Provision for loan and lease losses                 3,221 186 572
Balance at the end of year 4,413       1,192       4,413 1,192 1,006
Specific Reserve 0       0       0 0 0
General Allocation $ 4,413       $ 1,192       $ 4,413 $ 1,192 $ 1,006
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
v3.8.0.1
Allowance for Loan and Lease Losses and Unfunded Commitments and Letters of Credit (Changes in the Allowance for Unfunded Commitments and Letters of Credit) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Allowance For Loan And Lease Losses And Unfunded Loan Commitments And Letters Of Credit      
Beginning balance $ 2,705 $ 2,930 $ 2,655
Net changes in the allowance for unfunded commitments and letters of credit 425 (225) 275
Ending balance $ 3,130 $ 2,705 $ 2,930
v3.8.0.1
Allowance for Loan and Lease Losses and Unfunded Commitments and Letters of Credit (Analysis of Credit Quality of Loan Portfolio) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance $ 75,646 $ 70,043 $ 68,172 $ 69,569
Loans, net 8,283,011 6,143,380    
Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 8,245,987 6,067,763    
Loans and Leases Receivable, Allowance 68,739 59,528    
Loans, net 8,177,248 6,008,235    
Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 120,758 157,251    
Valuation discount resulting from acquisition accounting 8,088 11,591    
Loans and Leases Receivable, Allowance 6,907 10,515    
Loans, net 105,763 135,145    
Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 7,926,539 5,820,954    
Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 117,307 150,523    
Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 95,551 94,867    
Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 349 92    
Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 223,897 151,942    
Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 3,102 6,636    
Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial Portfolio Segment [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 13,753 21,606    
Commercial business: Secured loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 29,341 36,050 32,321 25,923
Commercial business: Secured loans [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 3,235,661 2,451,590    
Commercial business: Secured loans [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 12,641 20,870    
Commercial business: Secured loans [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 3,049,031 2,289,307    
Commercial business: Secured loans [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 11,918 18,824    
Commercial business: Secured loans [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 64,600 65,846    
Commercial business: Secured loans [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 92    
Commercial business: Secured loans [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 122,030 96,437    
Commercial business: Secured loans [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 723 1,954    
Commercial business: Secured loans [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Secured loans [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Secured loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Secured loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Unsecured loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 2,000 960 1,299 927
Commercial business: Unsecured loans [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 124,175 94,737    
Commercial business: Unsecured loans [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,112 736    
Commercial business: Unsecured loans [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 123,621 93,721    
Commercial business: Unsecured loans [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,045 736    
Commercial business: Unsecured loans [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 800    
Commercial business: Unsecured loans [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Unsecured loans [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 554 216    
Commercial business: Unsecured loans [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 67 0    
Commercial business: Unsecured loans [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Unsecured loans [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Unsecured loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Commercial business: Unsecured loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real Estate Portfolio Segment [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 93,821 115,438    
Real estate: One-to-four family residential [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 701 599 916 2,281
Real estate: One-to-four family residential [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 186,554 167,932    
Real estate: One-to-four family residential [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 14,610 20,643    
Real estate: One-to-four family residential [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 183,312 164,797    
Real estate: One-to-four family residential [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 13,817 19,293    
Real estate: One-to-four family residential [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,186 395    
Real estate: One-to-four family residential [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: One-to-four family residential [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 2,056 2,740    
Real estate: One-to-four family residential [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 793 1,350    
Real estate: One-to-four family residential [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: One-to-four family residential [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: One-to-four family residential [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: One-to-four family residential [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamily residential: Commercial land [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 4,265 1,797 1,178 799
Real estate: Commercial and multifamily residential: Commercial land [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 295,981 270,814    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 9,809 7,546    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 283,673 263,195    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 9,460 7,333    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 5,204 3,228    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 349 0    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 7,104 4,391    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 213    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamily residential: Commercial land [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Income property [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 5,672 7,342 6,616 9,159
Real estate: Commercial and multifamiIy residential: Income property [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,906,336 1,369,746    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 26,016 32,720    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,857,832 1,341,978    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 25,981 31,042    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 17,181 17,902    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 31,323 9,866    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 35 1,678    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Income property [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 5,459 6,439 5,550 5,007
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,599,986 1,059,978    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 43,386 54,529    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,546,775 1,027,019    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 42,617 53,623    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 7,380 6,608    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 45,831 26,351    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 769 906    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate: Commercial and multifamiIy residential: Owner occupied [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real Estate Construction Portfolio Segment [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 772 2,558    
Real estate construction: One-to-four family residential: Land and acquisition [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 963 316 339 1,197
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 9,907 11,556    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 177 832    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 9,882 11,541    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 169 744    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 25 15    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 8 88    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Land and acquisition [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 3,709 669 733 1,860
Real estate construction: One-to-four family residential: Residential construction [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 189,691 109,629    
Real estate construction: One-to-four family residential: Residential construction [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 187,863 108,941    
Real estate construction: One-to-four family residential: Residential construction [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 1,828 688    
Real estate construction: One-to-four family residential: Residential construction [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: One-to-four family residential: Residential construction [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 7,053 404 388 622
Real estate construction: Commercial and multifamily residential: Income property [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 293,028 103,779    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 595 1,217    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 293,028 103,779    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 595 1,217    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Income property [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 4,413 1,192 1,006 434
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 72,443 103,480    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 509    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 68,393 98,948    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 509    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 88    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 4,050 4,444    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Real estate construction: Commercial and multifamily residential: Owner occupied [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Consumer [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Allowance 5,163 3,534 $ 3,531 $ 3,180
Consumer [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 332,225 324,522    
Consumer [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 12,412 17,649    
Consumer [Member] | Pass [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 323,129 317,728    
Consumer [Member] | Pass [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 11,705 17,202    
Consumer [Member] | Special Mention [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Consumer [Member] | Special Mention [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Consumer [Member] | Substandard [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 9,096 6,794    
Consumer [Member] | Substandard [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 707 447    
Consumer [Member] | Doubtful [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Consumer [Member] | Doubtful [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Consumer [Member] | Unlikely to be Collected Financing Receivable [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount 0 0    
Consumer [Member] | Unlikely to be Collected Financing Receivable [Member] | Purchased Credit Impaired Loans [Member]        
Financing Receivable, Recorded Investment [Line Items]        
Loans and Leases Receivable, Gross, Carrying Amount $ 0 $ 0    
v3.8.0.1
Other Real Estate Owned (Summary of Other Real Estate Owned) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Other Real Estate Owned [Line Items]    
Other Real Estate Owned, established through acquisition $ 10,279 $ 0
Balance, beginning of period 5,998 13,738
Transfers in 106 1,047
Valuation adjustments (364) (860)
Proceeds from Sale of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans 2,590 8,158
Net realized gain on sale of other real estate owned (131) 231
Balance, end of period 13,298 $ 5,998
Mortgage Loans in Process of Foreclosure, Amount 302  
Real estate: One-to-four family residential [Member]    
Other Real Estate Owned [Line Items]    
Balance, end of period $ 74  
v3.8.0.1
FDIC Loss-sharing Asset and Covered Assets (Narrative) (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Covered Assets And FDIC Loss Sharing Asset [Line Items]                      
Payment from (to) FDIC to terminate loss-sharing agreements                 $ 4,666 $ 0 $ 0
Provision for loan and lease losses $ 3,327 [1] $ (648) $ 3,177 $ 2,775 $ 18 $ 1,866 $ 3,640 $ 5,254 8,631 10,778 8,591
FDIC Indemnification Asset $ 0       $ 3,535       0 3,535 6,568
FDIC Loss-sharing Asset, Cash Payments Paid to (Received from) the FDIC, net                 (184) (705)  
FDIC Loss-sharing Asset, Net Reimbursable Losses                 (149) (1,153)  
FDIC Loss-sharing Asset, Amortization, Net [3]                 (414) (2,829)  
FDIC Loss-sharing Asset, Impairment (Recapture) of Loans [3]                 40 301  
FDIC Loss-sharing Asset, Disposals [3]                 (18) (148)  
FDIC Loss-sharing Asset, Write-downs (Write-ups) of Other Real Estate [3]                 0 (22)  
FDIC Loss-sharing Asset, Other [3]                 (91) (183)  
Non-Single Family Covered Assets       74,000              
Single Family Covered Assets       $ 26,400              
FDIC indemnification asset settlement     (3,100)           (3,123) 0  
FDIC clawback liability removal upon termination of loss-sharing agreements     $ 5,400                
FDIC loss-sharing agreement early termination, pretax charge                 $ 2,409 $ 0 $ 0
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
[3] Amounts shown in the table above for adjustments reflected in noninterest income include only those adjustments recorded to the noninterest income line item “Change in FDIC loss-sharing asset” in the Consolidated Statements of Income and do not include the charge related to the termination of the FDIC loss-sharing agreements.
v3.8.0.1
Premises and Equipment (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Gross $ 240,253 $ 214,027  
Less accumulated depreciation and amortization (70,763) (63,685)  
Total 169,490 150,342  
Depreciation and amortization expense 9,800 11,800 $ 12,300
Land [Member]      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Gross 54,510 47,438  
Building [Member]      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Gross 110,216 101,196  
Leasehold Improvements [Member]      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Gross 24,184 19,491  
Furniture and Fixtures [Member]      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Gross 30,486 26,709  
Vehicles [Member]      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Gross 473 536  
Software [Member]      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Gross $ 20,384 $ 18,657  
v3.8.0.1
Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Goodwill and Intangible Assets [Line Items]      
Indefinite-Lived Intangible Assets (Excluding Goodwill) $ 919 $ 919 $ 919
Intangible Assets, Net (Excluding Goodwill) 58,173 17,631 23,577
Goodwill and Intangible Assets [Roll Forward]      
Total goodwill, beginning of period 382,762 382,762 382,537
Established through acquisitions [1] 383,080 0 225
Total goodwill, end of period 765,842 382,762 382,762
Core deposit intangible, net, beginning of period 17,631    
CDI current period amortization (6,333) (5,946) (6,882)
Total core deposit intangible, end of period 58,173 17,631  
Total goodwill and intangible assets, end of period 824,015 400,393 406,339
Core Deposits [Member]      
Goodwill and Intangible Assets [Roll Forward]      
Gross core deposit intangible balance, beginning of period 58,598 58,598 58,598
Accumulated amortization, beginning of period (41,886) (35,940) (29,058)
Core deposit intangible, net, beginning of period 16,712 22,658 29,540
Established through acquisitions 46,875 0 0
CDI current period amortization (6,333) (5,946) (6,882)
Total core deposit intangible, end of period $ 57,254 $ 16,712 $ 22,658
Estimated life of CDI, in years 10 years    
[1] See Note 2, Business Combinations, for additional information regarding the goodwill related to the acquisition of Pacific Continental on November 1, 2017.
v3.8.0.1
Goodwill and Intangible Assets (Summary of Estimated Future Amortization Expense of Core Deposit Intangibles) (Details) - Core Deposits [Member]
$ in Thousands
Dec. 31, 2017
USD ($)
Future Amortization Expense For Core Deposit Intangibles  
2016 $ 12,235
2017 10,479
2018 8,724
2019 7,264
2020 $ 5,880
v3.8.0.1
Deposits (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Deposits [Abstract]    
Brokered money market accounts $ 289,031 $ 208,348
Demand and other noninterest-bearing 5,081,901 3,944,495
Interest-bearing demand 1,265,212 985,293
Money market 2,543,712 1,791,283
Savings 861,941 723,667
Certificates of deposit less than $100,000 286,791 304,830
Total core deposits 10,039,557 7,749,568
Certificates of deposit greater than $100,000 100,399 79,424
Certificates of deposit insured by CDARS® 25,374 22,039
Other brokered certificates of deposit 78,481 0
Subtotal 10,532,842 8,059,379
Deposits, Valuation Adjustment From Acquisition Accounting (757) 36
Total deposits 10,532,085 8,059,415
Deposit Liabilities Reclassified as Loans Receivable 1,600 $ 4,400
Time Deposits, Fiscal Year Maturity [Abstract]    
2016 338,958  
2017 74,177  
2018 34,727  
2019 20,857  
2020 12,600  
Thereafter 9,726  
Total $ 491,045  
v3.8.0.1
Federal Home Loan Bank and Federal Reserve Bank Borrowings (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Debt Instrument [Line Items]      
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due within One Year of Balance Sheet Date 2.58%    
Federal Home Loan Bank, Advances, Maturities Summary, Fixed Rate, under One Year $ 4,000    
FHLB Fixed Rate Advances, Maturities Summary [Abstract]      
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, One To Five Years From Balance Sheet Date 3.85%    
FHLB Fixed Rate Advances, Over 1 through 5 years $ 2,000    
FHLB Fixed Rate Advances, Weighted Average Interest Rate, Due after 10 years 5.37%    
FHLB Fixed Rate Advances, Due after 10 years $ 5,000    
FHLB Fixed Rate Advances, Total Amount before valuation adjustment 11,000    
Valuation adjustment from acquisition accounting 579    
FHLB Fixed Rate Advances, Total Amount 11,579    
Federal Home Loan Bank, Advances, Activity for Year [Abstract]      
FHLB Advances 11,579 $ 6,493 $ 68,531
Average balance during the year 79,788 79,673 70,678
Maximum month-end balance during the year $ 317,480 $ 250,515 $ 242,556
Weighted average rate during the year 1.33% 0.80% 0.68%
Weighted average rate at December 31 4.08% 5.42% 0.79%
FHLB Advances, Collateral Pledged $ 1,443,554 $ 1,510,514  
FHLB Borrowing Capacity 1,432,554 1,502,284  
Federal Reserve Bank, Advances, Activity for Year [Abstract]      
Federal Reserve Bank, Advances, Collateral Pledged 100,054 61,007  
Federal Reserve Bank borrowing capacity 100,054 61,007  
Securities Investment [Member]      
Federal Reserve Bank, Advances, Activity for Year [Abstract]      
Federal Reserve Bank, Advances, Collateral Pledged 51,172 32,795  
Loans Receivable [Member]      
Federal Home Loan Bank, Advances, Activity for Year [Abstract]      
FHLB Advances, Collateral Pledged 1,443,554 1,510,514  
Commercial Loan [Member]      
Federal Reserve Bank, Advances, Activity for Year [Abstract]      
Federal Reserve Bank, Advances, Collateral Pledged $ 48,882 $ 28,212  
v3.8.0.1
Securities Sold Under Agreements to Repurchase (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Assets Sold under Agreements to Repurchase [Line Items]    
Carrying amount of securities pledged as collateral $ 419,383 $ 398,889
Available-for-sale Securities [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Assets Sold under Agreements to Repurchase, Sweep, Interest rate 0.11%  
Assets Sold under Agreements to Repurchase, Sweep, Carrying Amount $ 54,100  
Assets Sold under Agreements to Repurchase, Term, Carrying Amounts $ 25,000  
Assets Sold under Agreements to Repurchase, Term, Interest Rate 1.88%  
Repurchase Agreements, Sweep [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Carrying amount of securities pledged as collateral $ 66,500  
Repurchase Agreements,Term [Member]    
Assets Sold under Agreements to Repurchase [Line Items]    
Carrying amount of securities pledged as collateral $ 28,500  
v3.8.0.1
Subordinated debentures (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Nov. 01, 2017
Subordinated Borrowing [Line Items]    
Subordinated Borrowing, Interest Rate 5.875%  
Debt Instrument, Interest Rate Terms 471.5  
Pacific Continental [Member]    
Subordinated Borrowing [Line Items]    
Business Combination, Purchase Price Allocation, Subordinated Debt   $ 35.0
v3.8.0.1
Junior subordinated debt (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Nov. 01, 2017
junior subordinated debentures [Line Items]        
Junior Subordinated Debentures, Interest Rate 2.71%      
Repayments of Subordinated Debt $ 6,186 $ 0 $ 8,248  
Junior Subordinated Notes $ 8,248 $ 0    
Pacific Continental [Member]        
junior subordinated debentures [Line Items]        
Business Combination, Purchase Price Allocation, Junior Subordinated Debentures       $ 14,434
v3.8.0.1
Derivatives and Balance Sheet Offsetting (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Derivative [Line Items]      
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement $ 79,059    
Gain (Loss) on Derivative Instruments, Net, Pretax 16 $ 16 $ (11)
Secured Borrowings, Gross, Difference, Amount 0    
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]      
Derivative [Line Items]      
Derivative, Notional Amount 384,700 309,300  
Not Designated as Hedging Instrument [Member] | Other Assets [Member] | Interest Rate Contracts [Member]      
Derivative [Line Items]      
Derivative Asset, Fair Value, Gross Asset 6,707 9,012  
Not Designated as Hedging Instrument [Member] | Other Liabilities [Member] | Interest Rate Contracts [Member]      
Derivative [Line Items]      
Derivative Liability, Fair Value, Gross Liability 6,714 $ 9,036  
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]      
Derivative [Line Items]      
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement 79,059    
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] | Maturity Overnight [Member]      
Derivative [Line Items]      
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement 54,059    
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] | Maturity Less than 30 Days [Member]      
Derivative [Line Items]      
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement 0    
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] | Maturity 30 to 90 Days [Member]      
Derivative [Line Items]      
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement 25,000    
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] | Maturity Greater than 90 Days [Member]      
Derivative [Line Items]      
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement $ 0    
v3.8.0.1
Derivatives and Balance Sheet Offsetting Balance Sheet Offsetting (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Balance Sheet Offsetting [Line Items]    
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement $ 79,059  
Repurchase agreements, amounts offset in balance sheet 0 $ 0
repurchase agreements, net amount presented in statement of financial position 79,059 80,822
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities (79,059) (80,822)
securities sold under agreements to repurchase, amount not offset 0 0
Interest Rate Contracts [Member]    
Balance Sheet Offsetting [Line Items]    
Derivative Assets, Gross Amounts Offset in the Balance Sheets 0 0
Derivative Asset 6,707 9,012
Derivative, Collateral, Obligation to Return Securities 0 0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 6,707 9,012
Derivative Liability, Gross Amounts Offset in Balance Sheets 0 0
Derivative Liability 6,714 9,036
Derivative, Collateral, Right to Reclaim Securities (6,714) (9,036)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 0 0
Available-for-sale Securities [Member]    
Balance Sheet Offsetting [Line Items]    
Assets Sold under Agreements to Repurchase, Term, Carrying Amounts 25,000  
Assets Sold under Agreements to Repurchase, Carrying Amount 79,059 $ 80,822
Assets Sold under Agreements to Repurchase, Sweep, Carrying Amount $ 54,100  
v3.8.0.1
Employee Benefit Plans (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
USD ($)
years
period
shares
Dec. 31, 2016
USD ($)
shares
Dec. 31, 2015
USD ($)
shares
Employee Benefit [Line Items]      
Number of Look-back Period Under Employee Stock Purchase Plan | period 2    
Look-back Period Under Employee Stock Purchase Plan 6 months    
Discount On Common Stock Under Employee Stock Purchase Plan, Percent 10.00%    
Stock Issued During Period, Shares, Employee Stock Purchase Plans | shares 38,387 50,116 42,134
Stock Issued During Period, Value, Employee Stock Purchase Plan $ 1,500 $ 1,800 $ 1,200
Shares Available For Purchase Under Employee Stock Purchase Plan | shares 411,107    
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Balance at beginning of year $ 26,263 25,544  
Change in actuarial loss (6,453) 62  
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment 148 0  
Benefit expense 1,600 2,201  
Balance at end of year 20,553 26,263 25,544
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]      
Defined Benefit Plan, Benefit Obligation, Benefits Paid $ 1,005 1,544  
Pension Plan [Member]      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Requisite Service Period 1 month    
Deferred Compensation Arrangement with Individual, Contribution To Plan By Employee, Percent Of Eligible Compensation 75.00%    
Deferred Compensation Arrangement with Individual, Contribution Requirements, Matching Percent 50.00%    
Deferred Compensation Arrangement with Individual, Contributions by Employer $ 2,700 2,400 2,300
Pension Plan [Member] | Minimum [Member]      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Eligible Age | years 18    
Pension Plan [Member] | Maximum [Member]      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Contribution Requirements, Percent Of Each Employee Compensation 3.00%    
Deferred Profit Sharing [Member]      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Requisite Service Period 1 month    
Deferred Compensation Arrangement with Individual, Contribution To Plan By Employee, Percent Of Eligible Compensation 75.00%    
Deferred Compensation Arrangement with Individual, Contribution Requirements, Matching Percent 50.00%    
Deferred Compensation Arrangement with Individual, Contributions by Employer $ 5,700 5,100 5,200
Deferred Profit Sharing [Member] | Minimum [Member]      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Eligible Age | years 18    
Deferred Profit Sharing [Member] | Maximum [Member]      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Contribution Requirements, Percent Of Each Employee Compensation 3.00%    
ESP Plan [Member]      
Employee Benefit [Line Items]      
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date 90.00%    
Unit Plans [Member]      
Employee Benefit [Line Items]      
Deferred Compensation Arrangement with Individual, Vesting Period 10    
Deferred Compensation Arrangement with Individual, Benefit Period 10    
Deferred Compensation Arrangement with Individual, Recorded Liability $ 4,600 4,800  
Deferred Compensation Arrangement with Individual, Compensation Expense $ 452 $ 467 $ 859
SERP [Member]      
Employee Benefit [Line Items]      
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate 3.80% 4.09%  
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Normal Retirement Age | years 65    
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Annual Cost Of Living Benefit Adjustment 2.00%    
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]      
2016 $ 936    
2017 963    
2018 1,971    
2019 2,095    
2020 1,135    
2021 through 2025 7,563    
Total $ 14,663    
v3.8.0.1
Commitments and Contingent Liabilities (Details) - USD ($)
$ in Thousands
 12 Months Ended
Aug. 11, 2017
Aug. 24, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Minimum future rental payments:          
2016     $ 10,994    
2017     10,458    
2018     8,730    
2019     7,104    
2020     6,303    
Thereafter     14,482    
Total minimum payments     58,071    
Operating Leases, Rent Expense, Sublease Rentals     791 $ 992 $ 1,100
Operating Leases, Rent Expense, Net     7,900 8,700 $ 7,400
Commitments to Extend Credit [Member]          
Minimum future rental payments:          
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability     2,620,000 2,170,000  
Standby Letters of Credit [Member]          
Minimum future rental payments:          
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability     51,300 49,700  
Commercial Letter of Credit and other off-balance sheet liabilities [Member]          
Minimum future rental payments:          
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability     159 $ 3,400  
IDAHO          
Minimum future rental payments:          
Sale Leaseback Transaction, Date August 11, 2017        
Sale Leaseback Transaction, Monthly Rental Payments     26    
Sale Leaseback Transaction, Deferred Gain, Gross $ 509        
Sale Leaseback Transaction, Deferred Gain, Net     490    
WASHINGTON          
Minimum future rental payments:          
Sale Leaseback Transaction, Date   August 24, 2016      
Sale Leaseback Transaction, Monthly Rental Payments     12    
Sale Leaseback Transaction, Deferred Gain, Gross   $ 742      
Sale Leaseback Transaction, Deferred Gain, Net     $ 644    
v3.8.0.1
Shareholders' Equity (Details) - $ / shares
 12 Months Ended
Jan. 25, 2018
Oct. 19, 2017
Jul. 27, 2017
Apr. 27, 2017
Jan. 26, 2017
Apr. 02, 2013
Dec. 31, 2017
Class of Stock [Line Items]              
Declared quarterly cash dividend   $ 0.22 $ 0.22 $ 0.22 $ 0.22    
Subsequent Event [Member]              
Class of Stock [Line Items]              
Declared quarterly cash dividend $ 0.22            
Preferred Stock [Member]              
Class of Stock [Line Items]              
Stock Issued During Period, Shares, New Issues           8,782 0
v3.8.0.1
Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Accumulated Other Comprehensive Income (Loss), Net of Tax $ (22,225) $ (18,999) $ (6,295) $ 5,621
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax 626 (12,377) (11,123)  
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [1] 230 (327) (793)  
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent 856 (12,704) (11,916)  
Accumulated Net Unrealized Investment Gain (Loss) [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Accumulated Other Comprehensive Income (Loss), Net of Tax (19,779) (12,704) 386 7,462
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax (3,391) (12,338) (6,069)  
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [1] 7 (752) (1,007)  
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent (3,384) (13,090) (7,076)  
Accumulated Defined Benefit Plans Adjustment [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Accumulated Other Comprehensive Income (Loss), Net of Tax (2,446) (6,295) (6,681) $ (1,841)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax 4,017 (39) (5,054)  
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [1] 223 425 214  
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent 4,240 $ 386 $ (4,840)  
Accounting Standards Update 2018-02 [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption 0      
Accounting Standards Update 2018-02 [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption (3,691)      
Accounting Standards Update 2018-02 [Member] | Accumulated Defined Benefit Plans Adjustment [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption (391)      
Accounting Standards Update 2018-02 [Member] | Accumulated Other Comprehensive Income [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Cumulative Effect of New Accounting Principle in Period of Adoption $ (4,082)      
[1] (2) See following table for details about these reclassifications.
v3.8.0.1
Accumulated Other Comprehensive Income Amounts reclassified from Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]                      
Investment securities gains (losses), net                 $ (11) $ 1,181 $ 1,581
Income before income taxes $ 40,851 [1] $ 59,107 $ 38,252 $ 39,773 $ 43,035 $ 39,608 $ 36,650 $ 30,488 177,983 149,781 141,620
Income Tax Expense (Benefit) (25,123) [1] (18,338) (11,120) (10,574) (12,317) (12,124) (11,245) (9,229) (65,155) (44,915) (42,793)
Net income 15,728 [1] $ 40,769 $ 27,132 $ 29,199 $ 30,718 $ 27,484 $ 25,405 $ 21,259 112,828 104,866 98,827
Compensation and employee benefits                 169,674 150,282 149,410
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]                      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]                      
Investment securities gains (losses), net                 (11) 1,181 1,581
Income before income taxes                 (11) 1,181 1,581
Income Tax Expense (Benefit)                 4 (429) (574)
Net income                 (7) 752 1,007
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]                      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]                      
Income before income taxes                 (350) (668) (336)
Income Tax Expense (Benefit)                 127 243 122
Net income                 (223) (425) (214)
Compensation and employee benefits                 (350) $ (668) $ (336)
Accounting Standards Update 2018-02 [Member]                      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]                      
Cumulative Effect of New Accounting Principle in Period of Adoption 0               0    
Accounting Standards Update 2018-02 [Member] | Accumulated Other Comprehensive Income [Member]                      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]                      
Cumulative Effect of New Accounting Principle in Period of Adoption (4,082)               (4,082)    
Accounting Standards Update 2018-02 [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]                      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]                      
Cumulative Effect of New Accounting Principle in Period of Adoption (3,691)               (3,691)    
Accounting Standards Update 2018-02 [Member] | Accumulated Defined Benefit Plans Adjustment [Member]                      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]                      
Cumulative Effect of New Accounting Principle in Period of Adoption $ (391)               $ (391)    
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
v3.8.0.1
Fair Value Accounting and Measurement (Financial Assets And Liabilities Accounted for Fair Value On Recurring Basis) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale $ 2,742,831 $ 2,278,577
Fair Value, Measurements, Nonrecurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 6,577 3,787
Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 2,742,831 2,278,577
Other assets (Interest rate contracts) 6,707 9,012
Other liabilities (Interest rate contracts) 6,714 9,036
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 5,328 800
Other assets (Interest rate contracts) 0 0
Other liabilities (Interest rate contracts) 0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 2,737,503 2,277,777
Other assets (Interest rate contracts) 6,707 9,012
Other liabilities (Interest rate contracts) 6,714 9,036
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 6,577 3,787
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
Other assets (Interest rate contracts) 0 0
Other liabilities (Interest rate contracts) 0 0
U.S. Government Agency and Sponsored Enterprise Mortgage-Back Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 1,726,725 1,465,732
U.S. Government Agency and Sponsored Enterprise Mortgage-Back Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
U.S. Government Agency and Sponsored Enterprise Mortgage-Back Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 1,726,725 1,465,732
U.S. Government Agency and Sponsored Enterprise Mortgage-Back Securities and Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
State and Municipal Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 596,004 475,060
State and Municipal Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
State and Municipal Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 596,004 475,060
State and Municipal Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
U.S. Government Agency [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 414,774 331,902
U.S. Government Agency [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
U.S. Government Agency [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 414,774 331,902
U.S. Government Agency [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
US Treasury Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 248 800
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 248 800
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 0
Other Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount 5,100  
Other Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 5,080 5,083
Other Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 5,080 0
Other Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale 0 5,083
Other Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Securities available for sale $ 0 $ 0
v3.8.0.1
Fair Value Accounting and Measurement (Financial Assets Accounted For Fair Value On Nonrecurring Basis) (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans $ 6,577 $ 3,787
Other Real Estate Owned Fair Value 1,423 4,388
Losses During Period 2,746 5,745
Assets, Fair Value Disclosure 8,000 8,175
Fair Value, Inputs, Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 0 0
Other Real Estate Owned Fair Value 0 0
Assets, Fair Value Disclosure 0 0
Fair Value, Inputs, Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 0 0
Other Real Estate Owned Fair Value 0 0
Assets, Fair Value Disclosure 0 0
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 6,577 3,787
Other Real Estate Owned, Fair Value Disclosure 1,423 4,388
Other Real Estate Owned Fair Value 1,423 4,388
Assets, Fair Value Disclosure 8,000 8,175
Impaired Loans [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Losses During Period 2,507 5,413
Other Real Estate Owned [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Losses During Period $ 239 $ 332
v3.8.0.1
Fair Value Accounting and Measurement (Quantitative Information About Level 3 Fair Value Measurements) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Fair Value Inputs, Assets, Quantitative Information [Table Text Block]
The range and weighted-average of the significant unobservable inputs used to fair value our Level 3 nonrecurring assets during 2017 and 2016, along with the valuation techniques used, are shown in the following tables:
 
 
Fair value  at
December 31, 2017
 
Valuation Technique
 
Unobservable Input
 
Range (Weighted Average) (1)
 
 
(dollars in thousands)
Impaired loans - collateral-dependent (3)
 
$
3,519

 
Fair Market Value of Collateral
 
Adjustment to Stated Value
 
N/A (2)
Impaired loans - other
 
$
3,058

 
Discounted Cash Flow
 
Discount Rate
 
3.75% - 7.75% (4.12%)
OREO
 
$
1,423

 
Fair Market Value of Collateral
 
Adjustment to Appraisal Value
 
N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of real property and a government agency guarantee.

 
 
Fair value  at
December 31, 2016
 
Valuation Technique
 
Unobservable Input
 
Range (Weighted Average) (1)
 
 
(dollars in thousands)
Impaired loans - collateral-dependent (3)
 
$
2,248

 
Fair Market Value of Collateral
 
Adjustment to Stated Value
 
N/A (2)
Impaired loans - other
 
$
1,539

 
Discounted Cash Flow
 
Discount Rate
 
4.50% - 6.50% (5.26%)
OREO
 
$
4,388

 
Fair Market Value of Collateral
 
Adjustment to Appraisal Value
 
N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of accounts receivable, inventory, equipment and real property.
  
Fair Value, Measurements, Nonrecurring [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Other Real Estate Owned Fair Value $ 1,423 $ 4,388
Impaired loans 6,577 3,787
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Other Real Estate Owned Fair Value 1,423 4,388
Impaired loans 6,577 3,787
Other Real Estate Owned, Fair Value Disclosure $ 1,423 $ 4,388
v3.8.0.1
Fair Value Accounting and Measurement Fair Value Accounting and Measurement (Carrying Amounts and Estimated Fair Values of Selected Financial Instruments) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Assets    
Interest-earning deposits with banks $ 97,918 $ 31,200
Securities available for sale 2,742,831 2,278,577
Reported Value Measurement [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Junior subordinated debentures, fair value disclosure 8,248  
Subordinated Debt Obligations, Fair Value Disclosure 35,647  
Assets    
Cash and due from banks 244,615 193,038
Interest-earning deposits with banks 97,918 31,200
Securities available for sale 2,742,831 2,278,577
FHLB stock 10,440 10,240
Loans held for sale 5,766 5,846
Loans 8,283,011 6,143,380
FDIC loss-sharing asset   3,535
Interest rate contracts 6,707 9,012
Liabilities    
Deposits 10,532,085 8,059,415
FHLB Advances 11,579 6,493
Repurchase agreements 79,059 80,822
Interest rate contracts 6,714 9,036
Estimate of Fair Value Measurement [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Junior subordinated debentures, fair value disclosure 8,248  
Subordinated Debt Obligations, Fair Value Disclosure 35,895  
Assets    
Cash and due from banks 244,615 193,038
Interest-earning deposits with banks 97,918 31,200
Securities available for sale 2,742,831 2,278,577
FHLB stock 10,440 10,240
Loans held for sale 5,766 5,846
Loans 8,055,817 6,040,439
FDIC loss-sharing asset   867
Interest rate contracts 6,707 9,012
Liabilities    
Deposits 10,524,135 8,055,168
FHLB Advances 12,281 7,070
Repurchase agreements 79,070 81,131
Interest rate contracts 6,714 9,036
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value Measurement [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Junior subordinated debentures, fair value disclosure 0  
Subordinated Debt Obligations, Fair Value Disclosure 0  
Assets    
Cash and due from banks 244,615 193,038
Interest-earning deposits with banks 97,918 31,200
Securities available for sale 5,328 800
FHLB stock 0 0
Loans held for sale 0 0
Loans 0 0
FDIC loss-sharing asset   0
Interest rate contracts 0 0
Liabilities    
Deposits 10,041,040 7,653,122
FHLB Advances 0 0
Repurchase agreements 0 0
Interest rate contracts 0 0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Junior subordinated debentures, fair value disclosure 8,248  
Subordinated Debt Obligations, Fair Value Disclosure 35,895  
Assets    
Cash and due from banks 0 0
Interest-earning deposits with banks 0 0
Securities available for sale 2,737,503 2,277,777
FHLB stock 10,440 10,240
Loans held for sale 5,766 5,846
Loans 0 0
FDIC loss-sharing asset   0
Interest rate contracts 6,707 9,012
Liabilities    
Deposits 483,095 402,046
FHLB Advances 12,281 7,070
Repurchase agreements 79,070 81,131
Interest rate contracts 6,714 9,036
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Junior subordinated debentures, fair value disclosure 0  
Subordinated Debt Obligations, Fair Value Disclosure 0  
Assets    
Cash and due from banks 0 0
Interest-earning deposits with banks 0 0
Securities available for sale 0 0
FHLB stock 0 0
Loans held for sale 0 0
Loans 8,055,817 6,040,439
FDIC loss-sharing asset   867
Interest rate contracts 0 0
Liabilities    
Deposits 0 0
FHLB Advances 0 0
Repurchase agreements 0 0
Interest rate contracts $ 0 $ 0
v3.8.0.1
Fair Value Accounting and Measurement Fair Value, quantitative inputs to Level 3 measurements (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Impaired loans $ 6,577 $ 3,787
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Impaired loans 6,577 3,787
Other Real Estate Owned, Fair Value Disclosure 1,423 4,388
Real Estate Collateral [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Impaired loans   2,248
Other Collateral [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Impaired loans   $ 1,539
Not Collateral-Dependent [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Impaired loans 3,058  
Real Estate Collateral [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Impaired loans $ 3,519  
Income Approach Valuation Technique [Member] | Minimum [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Not Collateral-Dependent [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Fair Value Inputs, Discount Rate 3.75% 4.50%
Income Approach Valuation Technique [Member] | Maximum [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Not Collateral-Dependent [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Fair Value Inputs, Discount Rate 7.75% 6.50%
Income Approach Valuation Technique [Member] | Weighted Average [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Not Collateral-Dependent [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]    
Fair Value Inputs, Discount Rate 4.12% 5.26%
v3.8.0.1
Earnings Per Common Share (Schedule of Basic and Diluted Earnings Per Share) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
 [1]
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]                      
Basic earnings allocated to common shareholders                 $ 111,324 $ 103,310 $ 97,577
Net income $ 15,728 $ 40,769 $ 27,132 $ 29,199 $ 30,718 $ 27,484 $ 25,405 $ 21,259 112,828 104,866 98,827
Earnings allocated to participating securities - preferred shares                 3 185 175
Earnings allocated to participating securities - nonvested restricted shares                 $ 1,501 $ 1,371 $ 1,075
Weighted average common shares outstanding                 59,882 57,184 57,019
Basic earnings per common share $ 0.23 [3] $ 0.70 [3] $ 0.47 [3] $ 0.50 [3] $ 0.53 [3] $ 0.47 [3] $ 0.44 [3] $ 0.37 [3] $ 1.86 [3] $ 1.81 [3] $ 1.71
Earnings allocated to common shareholders, Diluted                 $ 111,324 $ 103,310 $ 97,577
Weighted average number of common shares outstanding                 59,882 57,184 57,019
Dilutive effect of equity awards and warrants                 6 9 13
Weighted average diluted common shares outstanding                 59,888 57,193 57,032
Diluted earnings per common share $ 0.23 [3] $ 0.70 [3] $ 0.47 [3] $ 0.50 [3] $ 0.53 [3] $ 0.47 [3] $ 0.44 [3] $ 0.37 [3] $ 1.86 [3] $ 1.81 [3] $ 1.71
Potentially dilutive share options that were not included in the computation of diluted EPS because to do so would be anti-dilutive.                 13 19 37
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
[3] Due to averaging of shares, quarterly earnings per share may not add up to the totals reported for the full year.
v3.8.0.1
Share-Based Payments (Share Awards) (Details) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Allocated Share-based Compensation Expense $ 7.7 $ 5.0 $ 4.1  
Share-based compensation, number authorized (in shares) 1,800,000      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number 805,706 818,755 665,702 519,785
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value $ 25.89 $ 25.81 $ 25.80 $ 23.03
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 337,384 335,593 306,007  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value $ 38.51 $ 28.40 $ 28.57  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (253,509) (153,235) (131,775)  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value $ 25.67 $ 23.80 $ 21.55  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period (96,924) (29,305) (28,315)  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value $ 28.97 $ 27.13 $ 24.79  
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized $ 18.6      
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition 2 years 5 months 27 days      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value $ 6.5 $ 3.6 $ 2.8  
v3.8.0.1
Share-Based Payments (Share Options) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Allocated Share-based Compensation Expense $ 7,700 $ 5,000 $ 4,100
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]      
Balance at beginning of year (in shares) 23,429    
Granted (in shares) 0 0 0
Forfeited (in shares) (577)    
Expired (in shares) (2,284)    
Exercised (in shares) (2,242)    
Balance at end of year (in shares) 18,326 23,429  
Total Exercisable Shares 18,326    
Weighted Average Exercise Price at beginning of year $ 45.98    
Weighted Average Exercise Price, Forfeited 54.70    
Weighted Average Exercise Price, Expired 135.97    
Weighted Average Exercise Price, Exercised 10.05    
Weighted Average Exercise Price at end of year 38.88 $ 45.98  
Exercisable, Weighted Average Exercise Price $ 38.88    
Weighted Average Remaining Contractual Term 7 months 27 days    
Aggregate Intrinsic Value $ 214    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number 18,326    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price $ 38.88    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term 7 months 27 days    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value $ 214    
Exercisable, Weighted Average Remaining Contractual Term 7 months 27 days    
Exercisable, Aggregate Intrinsic Value $ 214    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value $ 67 $ 232 $ 85
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]      
Number of Option Shares 18,326    
Weighted Average Remaining Contractual Life 7 months 27 days    
Weighted Average Exercise Price of Option Shares $ 38.88    
Number of Exercisable Option Shares 18,326    
Weighted Average Exercise Price of Exercisable Option Shares $ 38.88    
Stock-based compensation expense $ 7,745 $ 5,009 $ 4,090
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares 0    
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range From 0.00 To 9.99 [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]      
Range of Exercise Prices, Lower Limit $ 0.00    
Range of Exercise Prices, Upper Limit $ 9.99    
Number of Option Shares 6,393    
Weighted Average Remaining Contractual Life 1 year 3 months 24 days    
Weighted Average Exercise Price of Option Shares $ 9.91    
Number of Exercisable Option Shares 6,393    
Weighted Average Exercise Price of Exercisable Option Shares $ 9.91    
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range From 40.00 To 49.99 [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]      
Range of Exercise Prices, Lower Limit 40.00    
Range of Exercise Prices, Upper Limit $ 49.99    
Number of Option Shares 349    
Weighted Average Remaining Contractual Life 5 months 25 days    
Weighted Average Exercise Price of Option Shares $ 44.49    
Number of Exercisable Option Shares 349    
Weighted Average Exercise Price of Exercisable Option Shares $ 44.49    
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range From 50.00 To 136.93 [Member]      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]      
Range of Exercise Prices, Lower Limit 50.00    
Range of Exercise Prices, Upper Limit $ 136.93    
Number of Option Shares 11,584    
Weighted Average Remaining Contractual Life 3 months 19 days    
Weighted Average Exercise Price of Option Shares $ 54.70    
Number of Exercisable Option Shares 11,584    
Weighted Average Exercise Price of Exercisable Option Shares $ 54.70    
Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share Based Compensation Arrangement By Share Based Payment Award, Exercisable Period 5 years    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 3 years    
Share Based Compensation Arrangement By Share Based Payment Award, Maximum Term 10 years    
v3.8.0.1
Income Tax (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Contingency [Line Items]                      
Federal operating loss carryforwards, set to begin to expire in 2024 $ 24,800               $ 24,800    
Idaho state operating loss carryforwards, set to begin to expire in 2024 26,900               26,900    
Interest and penalties on unrecognized tax benefits                 0 $ 0  
State operating loss carryforwards, set to begin to expire in 2024 144               144    
Unrecognized tax position 0       $ 0       0 0  
Federal tax credit carryforwards 450               450    
Current tax (benefit) expense                 42,724 43,069 $ 36,426
Deferred tax expense (benefit)                 22,431 1,846 6,367
Income tax provision 25,123 [1] $ 18,338 $ 11,120 $ 10,574 12,317 $ 12,124 $ 11,245 $ 9,229 65,155 44,915 42,793
Deferred tax assets:                      
Allowance for loan and lease losses 18,315       26,638       18,315 26,638  
Supplemental executive retirement plan 9,539       16,232       9,539 16,232  
Stock option and restricted stock 1,438       1,922       1,438 1,922  
OREO 521       111       521 111  
Nonaccrual interest 163       320       163 320  
Deferred tax assets, purchase accounting 0       2,613       0 2,613  
Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross 5,992       7,492       5,992 7,492  
Deferred Tax Assets, Operating Loss Carryforwards 7,259       8,597       7,259 8,597  
Other (985)       (851)       (985) (851)  
Total deferred tax assets 44,212       65,835       44,212 65,835  
Deferred tax liabilities:                      
Asset purchase tax basis difference (5,709)       (9,037)       (5,709) (9,037)  
FHLB stock dividends (782)       (1,232)       (782) (1,232)  
Deferred loan fees (4,505)       (5,126)       (4,505) (5,126)  
Deferred tax liabilities, purchase accounting (9,088)       0       (9,088) 0  
Depreciation (1,581)       0       (1,581) 0  
Deferred Tax Liabilities, Other (2,036)       (155)       (2,036) (155)  
Total deferred tax liabilities 23,701       15,550       23,701 15,550  
Deferred Tax Assets, Property, Plant and Equipment 0       1,059       0 1,059  
Net deferred tax (liability) asset 20,511       50,285       20,511 50,285  
Reconciliation of effective income tax rate with federal statutory tax rate                      
Income tax based on statutory rate                 $ 62,262 $ 52,424 $ 49,567
Income tax based on statutory rate, percent                 35.00% 35.00% 35.00%
Federal income tax rate 2018                 21.00%    
Tax exempt instrument                 $ (8,485) $ (7,433) $ (6,761)
Tax exempt instrument, percent                 (5.00%) (5.00%) (5.00%)
Life insurance proceeds                 $ (3,351) $ (1,680) $ (1,554)
Life insurance proceeds, percent                 (2.00%) (1.00%) (1.00%)
effective income tax rate reconciliation, nondeductible expense, business combination, amount                 $ 825 $ 0 $ 0
effective income tax rate reconciliation, nondeductible expense, business combination, percent                 1.00% 0.00% 0.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount                 $ 12,210 $ 0 $ 0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent                 7.00% 0.00% 0.00%
Other, net                 $ 1,694 $ 1,604 $ 1,541
Other, net, percent                 1.00% 1.00% 1.00%
Income tax provision $ 25,123 [1] $ 18,338 $ 11,120 $ 10,574 $ 12,317 $ 12,124 $ 11,245 $ 9,229 $ 65,155 $ 44,915 $ 42,793
Income tax provision (benefit), percent                 37.00% 30.00% 30.00%
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
v3.8.0.1
Regulatory Capital Requirements (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Common Equity Tier One Capital $ 1,158,252 $ 873,217
Capital Conservation Buffer 4.9796%  
Common Equity Tier 1 Capital to Risk Weighted Assets 11.7421% 11.645%
Common Equity Tier One Capital Required for Capital Adequacy $ 443,886 $ 337,439
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets 4.50% 4.50%
Common Equity Tier One Capital Required for Capital Adequacy plus capital conservation buffer phase-in $ 567,187 $ 384,306
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in 5.75% 5.125%
Common Equity Tier One Capital Required for Capital Adequacy - minimum required plus fully phased in capital conservation buffer $ 690,489 $ 524,906
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in 7.00% 7.00%
Total Capital, Actual Amount $ 1,280,326 $ 947,436
Total Capital (to risk-weighted assets), Ratio 12.9796% 12.6347%
Total Capital For Capital Adequacy Purposes, Amount $ 789,130 $ 599,892
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio 8.00% 8.00%
Capital Required for Capital Adequacy plus capital conservation buffer phase-in $ 912,432 $ 646,759
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in 9.25% 8.625%
Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in $ 1,035,734 $ 787,359
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in 10.50% 10.50%
Tier 1 Capital, Actual Amount $ 1,165,903 $ 874,688
Tier 1 Capital (to risk-weighted assets), Ratio 11.8196% 11.6646%
Tier 1 Capital For Capital Adequacy Purposes, Amount $ 591,848 $ 449,919
Tier 1 Capital (to risk-weighted assets) For Capital Adequacy Purposes, Ratio 6.00% 6.00%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer phase-in $ 715,149 $ 496,786
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in 7.25% 6.625%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in $ 838,451 $ 637,386
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in 8.50% 8.50%
Tier 1 Capital, Actual Amount $ 1,165,903 $ 874,688
Tier 1 Capital (to average assets), Ratio 10.9611% 9.5526%
Tier 1 Capital For Capital Adequacy Purposes, Amount $ 425,469 $ 366,263
Tier 1 Capital (to average assets) For Capital Adequacy Purposes, Ratio 4.00% 4.00%
Banking Subsidiaries [Member]    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Common Equity Tier One Capital $ 1,184,476 $ 862,381
Capital Conservation Buffer 4.8123%  
Common Equity Tier 1 Capital to Risk Weighted Assets 12.0133% 11.5051%
Common Equity Tier One Capital Required for Capital Adequacy $ 443,687 $ 337,304
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets 4.50% 4.50%
Common Equity Tier One Capital Required for Capital Adequacy plus capital conservation buffer phase-in $ 566,933 $ 384,152
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in 5.75% 5.125%
Common Equity Tier One Capital Required for Capital Adequacy - minimum required plus fully phased in capital conservation buffer $ 690,180 $ 524,696
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in 7.00% 7.00%
Common Equity Tier One Risk Based Capital Required to be Well Capitalized $ 640,881 $ 487,217
Common Equity Tier 1 Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets 6.50% 6.50%
Total Capital, Actual Amount $ 1,263,252 $ 935,129
Total Capital (to risk-weighted assets), Ratio 12.8123% 12.4756%
Total Capital For Capital Adequacy Purposes, Amount $ 788,777 $ 599,652
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio 8.00% 8.00%
Capital Required for Capital Adequacy plus capital conservation buffer phase-in $ 912,023 $ 646,500
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in 9.25% 8.625%
Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in $ 1,035,269 $ 787,043
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in 10.50% 10.50%
Total Capital To Be Well Capitalized Under Prompt Corrective Action Provision, Amount $ 985,971 $ 749,565
Total Capital (to risk-weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provision 10.00% 10.00%
Tier 1 Capital, Actual Amount $ 1,184,476 $ 862,381
Tier 1 Capital (to risk-weighted assets), Ratio 12.0133% 11.5051%
Tier 1 Capital For Capital Adequacy Purposes, Amount $ 591,582 $ 449,739
Tier 1 Capital (to risk-weighted assets) For Capital Adequacy Purposes, Ratio 6.00% 6.00%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer phase-in $ 714,829 $ 496,587
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in 7.25% 6.625%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in $ 838,075 $ 637,130
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in 8.50% 8.50%
Tier 1 Capital To Be Well Capitalized Under Prompt Corrective Action Provision, Amount $ 788,777 $ 599,652
Tier 1 Capital (to risk-weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provision, Ratio 8.00% 8.00%
Tier 1 Capital, Actual Amount $ 1,184,476 $ 862,381
Tier 1 Capital (to average assets), Ratio 10.8186% 9.4275%
Tier 1 Capital For Capital Adequacy Purposes, Amount $ 437,939 $ 365,902
Tier 1 Capital (to average assets) For Capital Adequacy Purposes, Ratio 4.00% 4.00%
Tier 1 Capital To Be Well Capitalized Under Prompt Corrective Provision, Amount $ 547,423 $ 457,378
Tier 1 Capital (to average assets) To Be Well Capitalized Under Prompt Corrective Provision, Ratio 5.00% 5.00%
v3.8.0.1
Parent Company Financial Information (Condensed Balance Sheets) (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Assets        
Cash and due from banks $ 244,615 $ 193,038    
Interest-earning deposits 97,918 31,200    
Total cash and cash equivalents 342,533 224,238 $ 175,302 $ 188,170
Goodwill 765,842 382,762 382,762 382,537
Other assets 284,621 256,984    
Total Assets 12,716,886 9,509,607    
Subordinated Debt 35,647 0    
Junior Subordinated Notes 8,248 0    
Liabilities and Shareholders’ Equity        
Other liabilities 100,346 111,865    
Total liabilities 10,766,964 8,258,595    
Shareholders’ equity 1,949,922 1,251,012 1,242,128 1,228,175
Total liabilities and shareholders' equity 12,716,886 9,509,607    
Parent Company [Member]        
Assets        
Cash and due from banks 533 1,718    
Interest-earning deposits 8,765 729    
Total cash and cash equivalents 9,298 2,447 $ 3,989 $ 22,596
Goodwill [1] 4,729 7    
Other assets 3,426 5,139    
Total Assets 1,994,398 1,251,283    
Subordinated Debt 35,647 0    
Junior Subordinated Notes 8,248 0    
Liabilities and Shareholders’ Equity        
Other liabilities 581 271    
Total liabilities 44,476 271    
Shareholders’ equity 1,949,922 1,251,012    
Total liabilities and shareholders' equity 1,994,398 1,251,283    
Banking Subsidiaries [Member] | Parent Company [Member]        
Assets        
Investment in subsidiaries 1,971,788 1,238,712    
Other Subsidiaries [Member] | Parent Company [Member]        
Assets        
Investment in subsidiaries $ 5,157 $ 4,978    
[1] Reclassified to conform to current period’s presentation. The reclassification was limited to adding a separate line for Goodwill, which was previously included in other assets.
v3.8.0.1
Parent Company Financial Information (Condensed Statements of Income) (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
 [1]
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income                      
Deposits in banks                 $ 813 $ 216 $ 109
Expense                      
Compensation and employee benefits                 169,674 150,282 149,410
Interest Expense, Subordinated Notes and Debentures                 304 0 0
Other borrowings                 575 545 553
Other expense                 34,161 28,362 30,521
Income before income tax benefit and equity in undistributed (excess distributed) earnings of subsidiaries $ 40,851 $ 59,107 $ 38,252 $ 39,773 $ 43,035 $ 39,608 $ 36,650 $ 30,488 177,983 149,781 141,620
Provision for income taxes 25,123 18,338 11,120 10,574 12,317 12,124 11,245 9,229 65,155 44,915 42,793
Net income $ 15,728 $ 40,769 $ 27,132 $ 29,199 $ 30,718 $ 27,484 $ 25,405 $ 21,259 112,828 104,866 98,827
Parent Company [Member]                      
Income                      
Dividend from banking subsidiaries                 66,800 83,500 67,000
Deposits in banks                 2 4 5
Other income                 8 8 92
Total Income                 66,810 83,512 67,097
Expense                      
Compensation and employee benefits                 732 543 618
Interest Expense, Subordinated Notes and Debentures                 304 0 0
Other borrowings                 60 0 5
Other expense                 3,090 1,608 1,368
Total Expenses                 4,186 2,151 1,991
Income before income tax benefit and equity in undistributed (excess distributed) earnings of subsidiaries                 62,624 81,361 65,106
Provision for income taxes                 (548) (748) (663)
Income before equity in undistributed earnings of subsidiaries                 63,172 82,109 65,769
Equity in undistributed earnings of subsidiaries                 49,656 22,757 33,058
Net income                 $ 112,828 $ 104,866 $ 98,827
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
v3.8.0.1
Parent Company Financial Information (Condensed Statements of Cash Flows) (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]                      
Stock Issued                 $ 636,385 $ 0 $ 0
Operating Activities                      
Net income $ 15,728 [1] $ 40,769 $ 27,132 $ 29,199 $ 30,718 $ 27,484 $ 25,405 $ 21,259 112,828 104,866 98,827
Adjustments to reconcile net income to net cash provided by operating activities:                      
Stock-based compensation expense                 7,745 5,009 4,090
Net cash provided by operating activities                 128,525 145,847 134,756
Net cash received in business combinations                 80,472 0 0
Investing Activities                      
Net cash provided by investing activities                 (199,489) (548,553) (423,054)
Financing Activities                      
Payments of Ordinary Dividends, Preferred Stock and Preference Stock                 0 (157) (137)
Cash dividends paid                 (51,308) (88,677) (77,263)
Repayments of Subordinated Debt                 6,186 0 8,248
Payments for Repurchase of Equity                 (7,345) 0 0
Purchase and retirement of common stock                 (2,299) (1,125) (906)
Proceeds from exercise of stock options                 1,980 1,349 1,258
Excess tax benefit from stock-based compensation                 0 344 0
Net cash provided by financing activities                 189,259 451,642 275,430
Increase (decrease) in cash and cash equivalents                 118,295 48,936 (12,868)
Cash and cash equivalents at beginning of period       224,238       175,302 224,238 175,302 188,170
Cash and cash equivalents at end of period 342,533       224,238       342,533 224,238 175,302
Parent Company [Member]                      
Condensed Financial Statements, Captions [Line Items]                      
Stock Issued                 636,385 0 0
Operating Activities                      
Net income                 112,828 104,866 98,827
Adjustments to reconcile net income to net cash provided by operating activities:                      
Equity in undistributed earnings of subsidiaries                 (49,656) (22,757) (33,058)
Stock-based compensation expense                 7,745 5,009 4,090
Net changes in other assets and liabilities                 1,672 (394) (3,170)
Net cash provided by operating activities                 72,589 86,724 66,689
Net cash received in business combinations                 (580) 0 0
Investing Activities                      
Net cash provided by investing activities                 (580) 0 0
Financing Activities                      
Payments of Ordinary Dividends, Preferred Stock and Preference Stock                 0 (157) (137)
Cash dividends paid                 (51,308) (88,677) (77,263)
Repayments of Subordinated Debt                 6,186 0 8,248
Payments for Repurchase of Equity                 (7,345) 0 0
Purchase and retirement of common stock                 (2,299) (1,125) (906)
Proceeds from exercise of stock options                 1,980 1,349 1,258
Excess tax benefit from stock-based compensation                 0 344 0
Net cash provided by financing activities                 (65,158) (88,266) (85,296)
Increase (decrease) in cash and cash equivalents                 6,851 (1,542) (18,607)
Cash and cash equivalents at beginning of period       $ 2,447       $ 3,989 2,447 3,989 22,596
Cash and cash equivalents at end of period $ 9,298       $ 2,447       $ 9,298 $ 2,447 $ 3,989
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
v3.8.0.1
Summary Of Quarterly Financial Information (Unaudited) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
 [1]
Sep. 30, 2017
 [2]
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]                      
Total interest income $ 108,841 $ 90,303 $ 87,786 $ 87,816 $ 86,734 $ 86,758 $ 83,303 $ 81,174 $ 374,746 $ 337,969 $ 328,891
Total interest expense 2,617 1,374 1,625 1,141 997 1,186 1,163 1,004 6,757 4,350 4,004
Net Interest Income 106,224 88,929 86,161 86,675 85,737 85,572 82,140 80,170 367,989 333,619 324,887
Provision for loan and lease losses 3,327 (648) 3,177 2,775 18 1,866 3,640 5,254 8,631 10,778 8,591
Noninterest income 23,581 37,067 24,135 24,859 22,330 23,166 21,940 20,646 109,642 88,082 91,473
Noninterest expense 85,627 67,537 68,867 68,986 65,014 67,264 63,790 65,074 291,017 261,142 266,149
Income before income taxes 40,851 59,107 38,252 39,773 43,035 39,608 36,650 30,488 177,983 149,781 141,620
Provision for income taxes 25,123 18,338 11,120 10,574 12,317 12,124 11,245 9,229 65,155 44,915 42,793
Net income $ 15,728 $ 40,769 $ 27,132 $ 29,199 $ 30,718 $ 27,484 $ 25,405 $ 21,259 $ 112,828 $ 104,866 $ 98,827
Per Common Share                      
Earnings (basic) $ 0.23 [3] $ 0.70 [3] $ 0.47 [3] $ 0.50 [3] $ 0.53 [3] $ 0.47 [3] $ 0.44 [3] $ 0.37 [3] $ 1.86 [3] $ 1.81 [3] $ 1.71
Earnings (diluted) $ 0.23 [3] $ 0.70 [3] $ 0.47 [3] $ 0.50 [3] $ 0.53 [3] $ 0.47 [3] $ 0.44 [3] $ 0.37 [3] $ 1.86 [3] $ 1.81 [3] $ 1.71
[1] During the fourth quarter of 2017, Columbia acquired Pacific Continental Corporation and also recorded a charge through provision for income taxes related to the re-measurement of our deferred tax assets pursuant to the newly enacted Tax Cuts and Jobs Act. See Note 2, “Business Combinations” for further information regarding this acquisition. See Note 24, “Income Tax” for further information regarding the re-measurement of our deferred tax assets.
[2] During the third quarter of 2017, Columbia sold its merchant card services portfolio. See Note 1, “Summary of Significant Accounting Policies” for further information regarding this transaction.
[3] Due to averaging of shares, quarterly earnings per share may not add up to the totals reported for the full year.
v3.8.0.1
Subsequent Events (Details) - USD ($)
$ in Thousands
 12 Months Ended
Jan. 08, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Subsequent Event [Line Items]        
Junior Subordinated Notes   $ 8,248 $ 0  
Repayments of Subordinated Debt   $ 6,186 $ 0 $ 8,248
Subsequent Event [Member]        
Subsequent Event [Line Items]        
Repayments of Subordinated Debt $ 8,200