Document and Entity Information - shares	3 Months Ended	6 Months Ended
Document and Entity Information - shares	Mar. 31, 2018	Jun. 30, 2018
Document Information [Line Items]
Document Type	10-Q
Entity Registrant Name	Schneider National, Inc.
Amendment Flag	false
Document Period End Date		Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Trading Symbol	SNDR
Entity Central Index Key	0001692063
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Class A Common Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (shares)		83,029,500
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding (shares)		93,967,681

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
OPERATING REVENUES	$ 1,236.3	$ 1,075.2	$ 2,375.3	$ 2,081.6
OPERATING EXPENSES:
Purchased transportation	485.7	387.5	910.7	754.8
Salaries, wages, and benefits	314.7	304.9	626.0	602.6
Fuel and fuel taxes	88.2	71.2	172.9	144.4
Depreciation and amortization	71.9	68.6	143.6	136.5
Operating supplies and expenses	121.6	127.6	240.7	233.9
Insurance and related expenses	22.2	20.3	45.3	42.1
Other general expenses, net	40.3	16.1	76.8	44.8
Total operating expenses	1,144.6	996.2	2,216.0	1,959.1
INCOME FROM OPERATIONS	91.7	79.0	159.3	122.5
OTHER EXPENSES (INCOME):
Interest expense—net	3.9	4.6	7.4	10.1
Other expenses (income)—net	(0.5)	(0.2)	(0.9)	(0.1)
Total other expenses	3.4	4.4	6.5	10.0
INCOME BEFORE INCOME TAXES	88.3	74.6	152.8	112.5
PROVISION FOR INCOME TAXES	22.5	28.1	39.4	43.4
NET INCOME	(65.8)	(46.5)	(113.4)	(69.1)
OTHER COMPREHENSIVE INCOME (LOSS):
Foreign currency translation adjustments	0.5	(0.5)	0.1	(0.6)
Unrealized gain (loss) on marketable securities—net of tax	(0.1)	0.0	(0.3)	0.1
Total other comprehensive income (loss)	0.4	(0.5)	(0.2)	(0.5)
COMPREHENSIVE INCOME	$ 66.2	$ 46.0	$ 113.2	$ 68.6
Weighted average common shares issued and outstanding	177.0	174.4	177.0	165.4
Basic earnings per common share	$ 0.37	$ 0.27	$ 0.64	$ 0.42
Weighted average diluted shares outstanding (shares)	177.2	174.5	177.2	165.4
Diluted earnings per common share	$ 0.37	$ 0.27	$ 0.64	$ 0.42
Dividends per share of common stock (usd per share)	$ 0.06	$ 0.05	$ 0.12	$ 0.1

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 333.7	$ 238.5
Marketable securities	39.2	41.6
Trade accounts receivable—net of allowance of $7.0 and $5.2, respectively	568.0	527.9
Other receivables	19.6	22.4
Current portion of lease receivables—net of allowance of $0.7 and $1.7, respectively	122.1	104.9
Inventories	70.3	83.1
Prepaid expenses and other current assets	108.5	75.6
Total current assets	1,261.4	1,094.0
Property and equipment:
Transportation equipment	2,803.9	2,770.1
Land, buildings, and improvements	174.4	183.8
Other property and equipment	159.1	175.7
Total property and equipment	3,137.4	3,129.6
Accumulated depreciation	1,275.8	1,271.5
Net property and equipment	1,861.6	1,858.1
Lease receivables	129.2	138.9
Capitalized software and other noncurrent assets	76.6	74.7
Goodwill	164.6	164.8
Total noncurrent assets	2,232.0	2,236.5
TOTAL	3,493.4	3,330.5
CURRENT LIABILITIES:
Trade accounts payable	289.2	230.4
Accrued salaries and wages	75.4	85.8
Claims accruals - current	62.5	48.3
Current maturities of debt and capital lease obligations	9.5	19.1
Dividends payable	10.7	8.8
Other current liabilities	76.3	69.6
Total current liabilities	523.6	462.0
NONCURRENT LIABILITIES:
Long-term Debt and Capital Lease Obligations	415.2	420.6
Claims accruals - noncurrent	97.8	102.5
Deferred income taxes	416.7	386.6
Other	47.6	68.6
Total noncurrent liabilities	977.3	978.3
SHAREHOLDERS' EQUITY
Additional paid-in capital	1,537.6	1,534.6
Retained earnings	455.1	355.6
Accumulated other comprehensive income	(0.2)	0.0
Total shareholders' equity	1,992.5	1,890.2
TOTAL	3,493.4	3,330.5
Class A Common Shares
SHAREHOLDERS' EQUITY
Common stock	0.0	0.0
Class B Common Stock
SHAREHOLDERS' EQUITY
Common stock	$ 0.0	$ 0.0

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Trade allowance	$ (7.0)	$ (5.2)
Allowance for lease receivables	$ (0.7)	$ (1.7)
Class A Common Shares
Common stock, par value (usd per share)	$ 0
Common stock, shares authorized (shares)	250,000,000
Common stock, shares issued (shares)	83,029,500
Common stock, shares outstanding (shares)	83,029,500
Class B Common Stock
Common stock, par value (usd per share)	$ 0
Common stock, shares authorized (shares)	750,000,000
Common stock, shares issued (shares)	94,596,670
Common stock, shares outstanding (shares)	93,951,067

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash and Cash Equivalents, at Carrying Value	$ 333.7	$ 259.9
Payments for Previous Acquisition	19.3	19.4
OPERATING ACTIVITIES:
Net income	113.4	69.1
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	143.6	136.5
Gains on sales of property and equipment	(1.7)	(6.1)
Deferred income taxes	(27.7)	(36.3)
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	0.0	(12.9)
Share-based Compensation	10.4	11.1
Other noncash items	(3.2)	(0.3)
Changes in operating assets and liabilities:
Receivables	(37.3)	15.0
Other assets	17.9	(11.8)
Payables	36.9	2.0
Other liabilities	(16.9)	(12.2)
Net cash provided by operating activities	255.0	226.7
INVESTING ACTIVITIES:
Purchases of transportation equipment	(143.1)	(163.0)
Purchases of other property and equipment	(14.4)	(18.3)
Proceeds from sale of property and equipment	47.6	34.6
Proceeds from lease receipts and sale of off-lease inventory	36.8	29.9
Purchases of lease equipment	(34.7)	(52.0)
Sales of marketable securities	1.9	7.2
Net cash used in investing activities	(105.9)	(161.6)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract]
Repayments of Lines of Credit	0.0	135.0
Repayments of Debt and Capital Lease Obligations	15.1	114.8
Payments for Previous Acquisition	19.3	19.4
Proceeds from IPO, net of issuance costs	0.0	341.1
Payments of Dividends	19.5	7.8
Payments for Repurchase of Redeemable Preferred Stock	0.0	(0.1)
Net cash (used in) provided by financing activities	(53.9)	64.0
Cash and Cash Equivalents, Period Increase (Decrease)	95.2	129.1
Cash and Cash Equivalents, at Carrying Value	333.7	259.9
Noncash investing and financing activity:
Capital Expenditures Incurred but Not yet Paid	31.5	49.4
Dividends declared but not yet paid	10.7	8.8
Investment in Platform Science, Inc.	2.5	0.0
Costs in accounts payable related to our IPO	0.0	0.4
Cash paid (refunded) during the period for:
Interest	7.8	11.1
Income taxes—net of refunds	$ 19.7	$ (13.5)

General	6 Months Ended
General	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	GENERAL Description of Business In this report, when we refer to “the Company,” “us,” “we,” “our,” or “ours,” we are referring to Schneider National, Inc. and its subsidiaries. We are a leading transportation services organization headquartered in Green Bay, Wisconsin. We provide a broad portfolio of premier truckload, intermodal, and logistics solutions and operate one of the largest trucking fleets in North America. Our IPO of shares of Class B Common Stock was completed in early April 2017, and additional shares were sold in May 2017 under an option granted to the underwriters. In connection with the offering, we sold a total of 20,145,000 shares of common stock at $19 per share and received proceeds of $382.7 million. Expenses related to the offering totaled approximately $42.1 million, resulting in net proceeds of $340.6 million. Basis of Presentation The accompanying unaudited interim Consolidated Financial Statements have been prepared in accordance with GAAP and the rules and regulations of the SEC applicable to quarterly reports on Form 10-Q. Therefore, these financial statements and footnotes do not include all disclosures required by GAAP for annual financial statements. These financial statements should be read in conjunction with the Consolidated Financial Statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2017. Financial results for an interim period are not necessarily indicative of the results for a full year. All intercompany transactions have been eliminated in consolidation. In the opinion of management, these statements reflect all adjustments (consisting only of normal recurring adjustments) necessary for the fair presentation of our financial results for the interim periods presented. Accounting Standards Issued But Not Yet Adopted In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income, which discusses the reclassification of certain tax effects from accumulated other comprehensive income. The guidance requires companies to disclose a description of their accounting policy for releasing income tax effects from accumulated other comprehensive income and whether they elect to reclassify the stranded income tax effects from the Tax Cuts and Jobs Act, along with information about other income tax effects that are reclassified. The guidance is effective for us as of January 1, 2019 with early adoption permitted. We plan to early adopt this guidance during the fourth quarter of 2018 and expect the reclassification of stranded income tax effects to have an immaterial impact on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases, which is codified as ASC 842. Subsequent ASUs have clarified and modified this guidance. This standard requires lessees to recognize assets and liabilities in the consolidated balance sheets for leases with lease terms of more than 12 months. Consistent with current accounting principles, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance or operating lease. However, unlike current accounting principles, which require only capital leases to be recognized in the consolidated balance sheets, the new ASU will require both types of leases to be recognized in the consolidated balance sheets. In transition, lessees and lessors can elect to recognize and measure leases at the date of adoption or at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that companies may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. The transition guidance also provides specific guidance for sale and leaseback transactions, build-to-suit leases, leveraged leases, and amounts previously recognized in accordance with the business combinations guidance for leases. The new standard is effective for us as of January 1, 2019 with early adoption permitted. We have formed a cross-functional implementation team that has both identified the population of the company's lease contracts affected by the new standard and selected a system to help accommodate the new leasing standard. We have not yet completed our assessment of the impact of the new guidance on our consolidated financial statements; however, we do expect an increase in our assets and liabilities from the recognition of operating leases on the consolidated balance sheets. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments, which requires companies to use a forward-looking, expected loss model to estimate credit losses on various types of financial assets and net investments in leases. It also requires additional disclosure related to credit quality of trade and other receivables, including information related to management’s estimate of credit allowances. This guidance is effective for us as of January 1, 2020. We currently cannot reasonably estimate the impact that the adoption of this ASU will have on our consolidated financial statements.

Revenue Recognition Revenue Recognition

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Revenue from Contract with Customer [Text Block]

REVENUE RECOGNITION

We implemented ASU 2014-09, Revenue from Contracts with Customers, which is codified as ASC 606 as of January 1, 2018. We used the modified retrospective approach for adoption, which required us to record the cumulative effect of the transition through retained earnings as of January 1, 2018. Retained earnings increased by $7.3 million upon adoption. The adjustment related only to contracts that were not completed as of January 1, 2018. The following table shows the amount by which financial statement lines were affected by the adoption of the new standard. The changes relate to the recognition of transportation revenue over time rather than at delivery, as explained below under the Transportation heading.



	Three Months Ended June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605		Adjustment		As Reported
Consolidated Statement of Comprehensive Income
Operating revenues	$	1,231.3	$	5.0	$	1,236.3
Purchased transportation	482.7		3.0		485.7
Salaries, wages, and benefits	313.8		0.9		314.7
Total operating expenses	1,140.7		3.9		1,144.6
Income from operations	90.6		1.1		91.7
Provision for income taxes	22.2		0.3		22.5
Net income	65.0		0.8		65.8
Comprehensive Income	65.4		0.8		66.2



	Six Months Ended June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605		Adjustment		As Reported
Consolidated Statement of Comprehensive Income
Operating revenues	$	2,369.8	$	5.5	$	2,375.3
Purchased transportation	906.9		3.8		910.7
Salaries, wages, and benefits	624.8		1.2		626.0
Total operating expenses	2,211.0		5.0		2,216.0
Income from operations	158.8		0.5		159.3
Provision for income taxes	39.3		0.1		39.4
Net income	113.0		0.4		113.4
Comprehensive Income	112.8		0.4		113.2



	June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605		Adjustment		As Reported
Consolidated Balance Sheet
Prepaid expenses and other current assets	$	84.8	$	23.7	$	108.5
Total current assets	1,237.7		23.7		1,261.4
Total assets	3,469.7		23.7		3,493.4
Other current liabilities	62.7		13.6		76.3
Total current liabilities	510.0		13.6		523.6
Deferred income taxes	414.3		2.4		416.7
Total noncurrent liabilities	974.9		2.4		977.3
Retained earnings	447.4		7.7		455.1
Total shareholders' equity	1,984.8		7.7		1,992.5
Total liabilities and shareholders' equity	3,469.7		23.7		3,493.4



	Six Months Ended June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605			Adjustment			As Reported
Consolidated Statement of Cash Flows
Operating Cash Flows
Net income	$	113.0		$	0.4		$	113.4
Change in: Other assets	(12.4		)	(5.5		)	(17.9		)
Change in: Payables	36.8			0.1			36.9
Change in: Other liabilities	(21.9		)	5.0			(16.9		)

ASC 606 requires us to look at revenue from customers at a contract level to determine the appropriate accounting. As defined by the new standard, a "contract" can range from an individual order to a multi-year agreement with a customer, depending on the specific arrangement. The majority of our revenues are related to transportation and have similar characteristics. The following table breaks down our revenues by type of service, and each type of service is further described below.



	Three Months Ended June 30,				Six Months Ended June 30,
Disaggregated Revenues (in millions)	2018		2017		2018		2017
Transportation	$	1,138.0	$	979.8	$	2,187.9	$	1,915.3
Logistics management	53.9		52.5		106.0		104.8
Other	44.4		42.9		81.4		61.5
Total operating revenues	$	1,236.3	$	1,075.2	$	2,375.3	$	2,081.6

Transportation

Transportation revenues relate to the Truckload and Intermodal reportable segments, as well as to our Brokerage business, which is included in the Logistics reportable segment.

In the Transportation portfolio, our service obligation to customers is satisfied over time. We do not believe there is a significant impact on the nature, amount, timing, and uncertainty of revenue or cash flows based on the mode of transportation. The economic factors that impact our transportation revenue are generally consistent across these modes given the relatively short term nature of each contract. For the majority of our transportation business, the "contract with a customer" is identified as an individual order under a negotiated agreement. Some consideration is variable in that a final transaction price is uncertain and is susceptible to factors outside of Schneider's influence, such as the weather or the accumulation of accessorial charges. Pricing information is supplied by the rate schedules that accompany negotiated contracts.

Transportation orders are short-term in nature and generally have terms of significantly less than one year. They do not include significant financing components. A small portion of revenues in our transportation business relate to fixed payments in our Truckload segment. These payments are due regardless of volumes, and in these arrangements, the master agreement rather than the individual order may be considered the "contract." See the Remaining Performance Obligations table below for more information on fixed payments.

Prior to the adoption of ASC 606, we recognized revenue from transportation services when we completed our obligation to the customer, upon delivery. In accordance with the new standard, we now recognize revenue over the period transportation services are provided to the customer, including service performed as of the end of the reporting period for loads currently in transit, in order to recognize the value that is transferred to a customer over the course of the transportation service.

We determine revenue in transit using the input method, under which revenue is recognized based on time lapsed from the departure date (start of transportation services) to the arrival date (completion of transportation services). Measurement of revenue in transit requires the application of significant judgment. We calculate the estimated percentage of an order's transit time that is complete at period end, and we apply that percentage of completion to the order's estimated revenue. Revenue recognized in the period ended June 30, 2018 includes amounts related to orders that were partially completed (in transit) in prior periods.

In certain transportation arrangements, an unrelated party contributes a specified service to our customer. For example, we contract with third-party carriers to perform transportation services on behalf of our customers in our Brokerage business, and we use third-party rail carriers in our Intermodal segment. In situations that include the contributions of third parties, we act as principal in the arrangement, and, accordingly, we recognize gross revenues from these transactions.

Logistics Management

Logistics Management revenues relate to our Supply Chain Management and Import/Export Services operating segments, both of which are included in our Logistics reportable segment. Within this portfolio, the key service we provide to the customer is management of freight shipping and/or storage.

The "contracts" in our Logistics Management portfolio are the negotiated agreements, which contain both fixed and variable components. The variability of revenues is driven by volumes and transactions, which are known as of an invoice date. See the Remaining Performance Obligations table below for additional information. Supply Chain Management and Import/Export Services contracts typically have terms that extend beyond one year, and they do not include financing components.

Prior to the adoption of ASC 606, we recognized revenue under these contracts over time, based on pricing terms within the arrangements. Our recognition model will remain the same under the new standard, as we have elected to use the right to invoice practical expedient, which reflects the fact that a customer obtains the benefit associated with logistics services as they are provided (output method).

In our Supply Chain Management business, we subcontract third parties to perform a portion of the services. We are responsible for ensuring the services are performed and that they are acceptable to the customer, and we are therefore considered to be the principal in these arrangements.

Other

Other revenues relate to activities that are out of scope for purposes of ASC 606, including our leasing and captive insurance businesses.

Quantitative Disclosure

The following table provides information related to the transactions and expected timing of revenue recognition related to performance obligations that are fixed in nature and relate to contracts with terms greater than one year.



Remaining Performance Obligations (in millions)	June 30, 2018
Expected to be recognized within one year
Transportation	$	12.1
Logistics Management	10.0
Expected to be recognized after one year
Transportation	1.0
Logistics Management	4.0
Total	$	27.1

This disclosure does not include revenue related to performance obligations that are part of a contract whose original expected duration is one year or less. In addition, this disclosure does not include expected consideration related to performance obligations for which the Company elects to recognize revenue in the amount it has a right to invoice (e.g., usage-based pricing terms).

The following table provides information related to contract balances associated with our contracts with customers as of the dates shown.



Contract Balances (in millions)	June 30, 2018		January 1, 2018
Other current assets - contract assets	$	27.8	$	22.2
Other current liabilities - contract liabilities	$	1.1	$	—

We generally receive payment within 40 days of completion of performance obligations. Contract assets in the table above relate to revenue in transit at the end of the reporting period. Contract liabilities relate to amounts that customers paid in advance of the associated service.

For certain of our contracts, we incur upfront costs to fulfill the master agreement, including driver recruiting and equipment relocation, that are capitalized and amortized over the master contract term, which has been deemed to be the period of benefit. These costs usually relate to dedicated transportation arrangements. The following table presents the amounts capitalized for contract fulfillment costs as of the dates shown.



(in millions)	June 30, 2018		December 31, 2017
Capitalized contract fulfillment costs	$	4.5	$	3.7

Amortization of capitalized contract fulfillment costs was as shown:



	Three Months Ended June 30,				Six Months Ended June 30,
(in millions)	2018		2017		2018		2017
Amortization of contract fulfillment costs	$	0.8	$	0.5	$	1.4	$	1.1

Practical Expedients

We elected to use the following practical expedients that are available under ASC 606: (i) not to adjust the promised amount of consideration for the effects of a significant financing component when we expect, at contract inception, that the period between our transfer of a promised service to a customer and when the customer pays for that service will be one year or less; (ii) to apply the new revenue standard to a portfolio of contracts (or performance obligations) with similar characteristics, as we reasonably expect that the effects on the financial statements of applying this guidance to the portfolio would not differ materially from applying this guidance to the individual contracts (or performance obligations) within that portfolio; and (iii) to recognize revenue in the Logistics Management portfolio in the amount of consideration to which we have a right to invoice, that corresponds directly with the value to the customer of the service completed to date.

Fair Value

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value

FAIR VALUE

Fair value focuses on the estimated price that would be received to sell an asset or paid to transfer a liability, which is referred to as the exit price. Inputs to valuation techniques used to measure fair value fall into three broad levels (Levels 1, 2, and 3) as follows:

Level 1—Observable inputs that reflect quoted prices for identical assets or liabilities in active markets that we have the ability to access at the measurement date.

Level 2—Observable inputs, other than quoted prices included in Level 1, for the asset or liability or prices for similar assets and liabilities.

Level 3—Unobservable inputs reflecting the reporting entity’s estimates of the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk).

All marketable securities were valued based on quoted prices for similar assets in active markets or quoted prices for identical or similar assets in markets that are not active (Level 2 in the fair value hierarchy). We measure our marketable securities on a recurring, monthly basis. See Note 4, Investments, for information on the fair value of our marketable securities.

In connection with the June 1, 2016 acquisition of WSL, a contingent payment arrangement based on the achievement of specified earnings targets is in place for three consecutive 12-month periods after the closing, with the aggregate payment total not to exceed $40.0 million. No payments have been made through June 30, 2018. The fair value of the contingent consideration at June 30, 2018 and December 31, 2017 was zero. The valuation was based on Level 3 inputs.

Our investment in Platform Science, Inc. discussed in Note 4, Investments, was valued based on Level 3 inputs.

There were no transfers between levels for the periods discussed.

Fair Value of Other Financial Instruments

The recorded value of cash, trade accounts receivable, and trade accounts payable approximates fair value.

The table below presents the carrying value of our debt portfolio along with the fair value of a fixed-rate debt portfolio with similar terms and maturities, which is based on borrowing rates available to us in the applicable year. This valuation used Level 2 inputs.



	June 30, 2018				December 31, 2017
(in millions)	Carrying Value		Fair Value		Carrying Value		Fair Value
Debt portfolio	$	416.6	$	407.0	$	429.8	$	432.4

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Investments

6 Months Ended

Jun. 30, 2018

Investments Schedule [Abstract]

Investment [Text Block]

INVESTMENTS

Marketable Securities

Our marketable securities are classified as available for sale and carried at fair value in current assets on the consolidated balance sheets. Any unrealized gains and losses, net of tax, are included as a component of accumulated other comprehensive income. Our portfolio of securities have maturities ranging from 3 to 72 months. While our intent is to hold our securities to maturity, sudden changes in the market or to our liquidity needs may cause us to sell certain securities in advance of their maturity date.

The following table presents the values of our marketable securities as of the dates shown.



	June 30, 2018				December 31, 2017
(in millions)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Zero coupon bonds	$	3.9	$	3.9	$	3.8	$	3.9
U.S. treasury and government agencies	14.0		13.7		6.0		6.0
Asset-backed securities	0.1		0.1		0.3		0.3
Corporate debt securities	9.1		9.0		9.1		9.2
State and municipal bonds	12.7		12.5		22.7		22.2
Total marketable securities	$	39.8	$	39.2	$	41.9	$	41.6

Gross realized and unrealized gains and losses on sales of marketable securities were not material for the three and six months ended June 30, 2018 and 2017.

Investment in Platform Science, Inc.

In 2018, we acquired a 30% ownership interest in Platform Science, Inc. In exchange for this ownership interest, we contributed a non-exclusive license for telematics mobile software that was developed to enable driver productivity and ensure regulatory compliance. Our investment in Platform Science, Inc. is recorded at fair value in other noncurrent assets on the consolidated balance sheet. The fair value of the investment was initially determined to be $2.5 million and is being accounted for under ASC 321, Investments - Equity Securities.

Goodwill and Other Intangible Assets

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

GOODWILL AND OTHER INTANGIBLE ASSETS

Goodwill represents the excess of the purchase price of our acquisitions over the fair value of the identifiable net assets acquired. Changes in the carrying amount of goodwill were as follows:



(in millions)	Truckload		Logistics		Other			Total
Balance at December 31, 2017	$	138.2	$	14.2	$	12.4		$	164.8
Foreign currency translation	—		—		(0.2		)	(0.2		)
Balance at June 30, 2018	$	138.2	$	14.2	$	12.2		$	164.6

At June 30, 2018 and December 31, 2017, we had accumulated goodwill impairment charges of $6.0 million.

Prior to the second quarter of 2018, all of the goodwill within the Truckload reportable segment was attributed to the Specialty Dedicated reporting unit. During the quarter ended June 30, 2018, we reorganized the structure of the operating segments within the Truckload reportable segment to include FTFM as a separate operating segment and integrated the remaining Specialty Dedicated activities into the VTL operating segment. Each Truckload operating segment was determined to be its own reporting unit due to the level at which financial information is available and management's review of that information. As a result of the reorganization, goodwill attributable to the Specialty Dedicated reporting unit was reallocated to the VTL and FTFM reporting units on a relative fair value basis. After the reallocation of goodwill, an impairment test was performed for these reporting units, and it was determined that goodwill was not impaired as each reporting unit had an estimated fair value in excess of its respective carrying amount.

The identifiable intangible assets other than goodwill listed below are included in other noncurrent assets on the consolidated balance sheets.



	June 30, 2018						December 31, 2017
(in millions)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Customer lists	$	10.5	$	3.0	$	7.5	$	10.5	$	2.5	$	8.0
Trade names	1.4		1.0		0.4		1.4		0.7		0.7
Total intangible assets	$	11.9	$	4.0	$	7.9	$	11.9	$	3.2	$	8.7

Amortization expense for intangible assets was $0.4 million for each of the three months ended June 30, 2018 and 2017, and $0.7 million and $0.8 million for the six months ended June 30, 2018 and 2017, respectively. Accumulated amortization in the table above includes foreign currency translation related to a customer list.

Estimated future amortization expense related to intangible assets is as follows (in millions):



Remaining 2018	$	0.6
2019	1.1
2020	1.0
2021	1.0
2022	1.0
2023 and thereafter	3.2
	$	7.9

Debt and Credit Facilities

3 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

Debt and Credit Facilities

DEBT AND CREDIT FACILITIES

As of June 30, 2018 and December 31, 2017, debt included the following:



(in millions)	June 30, 2018			December 31, 2017
Unsecured senior notes: principal payable at maturities ranging from 2019 through 2025; interest payable in semiannual installments through the same timeframe; weighted-average interest rate of 3.36% for both 2018 and 2017	$	400.0		$	400.0
Equipment financing notes: principal and interest payable in monthly installments through 2023; weighted average interest rate of 3.80% and 3.76% for 2018 and 2017, respectively	16.6			29.8
Total principal outstanding	416.6			429.8
Current maturities	(6.3		)	(15.2		)
Debt issuance costs	(0.8		)	(0.9		)
Long-term debt	$	409.5		$	413.7

Our master revolving credit agreement provides borrowing capacity of up to $250.0 million through November 2018. This agreement also provides a sublimit of $100.0 million to be used for the issuance of letters of credit. We had no outstanding borrowings under this agreement as of June 30, 2018 or December 31, 2017. Standby letters of credit under this agreement amounted to $3.9 million at June 30, 2018 and December 31, 2017, and were primarily related to the requirements of certain of our real estate leases.

We have a secured credit facility that allows us to borrow up to $200.0 million against qualifying trade receivables at rates based on the 30-day London InterBank Offered Rate through September 2018. We had no outstanding borrowings under this facility at June 30, 2018 or December 31, 2017. At June 30, 2018 and December 31, 2017, standby letters of credit under this agreement amounted to $62.8 million and $63.8 million, respectively, and were primarily related to the requirements of certain of our insurance obligations.

Lease Receivables

3 Months Ended

Mar. 31, 2018

Leases [Abstract]

Lease Receivables

LEASE RECEIVABLES

We finance various types of transportation-related equipment for independent third parties. The transactions are generally for one to five years and are accounted for as sales-type or direct financing leases. As of June 30, 2018 and December 31, 2017, the investment in lease receivables was as follows:



(in millions)	June 30, 2018			December 31, 2017
Future minimum payments to be received on leases	$	140.1		$	141.2
Guaranteed residual lease values	139.7			130.7
Total minimum lease payments to be received	279.8			271.9
Unearned income	(28.5		)	(28.1		)
Net investment in leases	251.3			243.8

Current maturities of lease receivables	122.8			106.6
Less—allowance for doubtful accounts	(0.7		)	(1.7		)
Current portion of lease receivables—net of allowance	122.1			104.9

Lease receivables—noncurrent	$	129.2		$	138.9

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Our effective income tax rate was 25.5% and 37.7% for the three months ended June 30, 2018 and 2017, respectively, and 25.8% and 38.6% for the six months ended June 30, 2018 and 2017, respectively. The decrease in the rates was due to the enactment of the Tax Cuts and Jobs Act in December 2017. In determining the quarterly provision for income taxes, we use an estimated annual effective tax rate, adjusted for discrete items. This rate is based on our expected annual income, statutory tax rates, and best estimate of nontaxable and nondeductible items of income and expense. In accordance with SEC Staff Accounting Bulletin No. 118, the amounts recorded in the fourth quarter of 2017 related to the Tax Cuts and Jobs Act represent reasonable estimates based on our analysis to date and are considered to be provisional and subject to revision during 2018. Provisional amounts were recorded for the remeasurement of our 2017 net deferred tax liabilities and ancillary state tax effects. These amounts are considered to be provisional as we continue to assess available tax methods and elections and refine our computations. In addition, further regulatory guidance related to the Tax Cuts and Jobs Act is expected to be issued in 2018 which may result in changes to our current estimates. Any revisions to the estimated impacts of the Tax Cuts and Jobs Act will be recorded quarterly until the computations are complete, which is expected to be no later than the fourth quarter of 2018. No changes were made to the estimated impacts in the second quarter of 2018.

Common Equity

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Common Equity

COMMON EQUITY

Earnings Per Share

The following table sets forth the computation of basic and diluted earnings per share for the three and six months ended June 30, 2018 and 2017.



	Three Months Ended June 30,				Six Months Ended June 30,
(in millions, except per share data)	2018		2017		2018		2017
Basic earnings per common share:
Net income available to common shareholders	$	65.8	$	46.5	$	113.4	$	69.1
Weighted average common shares issued and outstanding	177.0		174.4		177.0		165.4
Basic earnings per common share	$	0.37	$	0.27	$	0.64	$	0.42
Diluted earnings per common share:
Net income applicable to diluted earnings per common share	$	65.8	$	46.5	$	113.4	$	69.1
Dilutive potential common shares:
Restricted share units	0.2		0.1		0.2		—
Dilutive potential common shares	0.2		0.1		0.2		—
Total diluted average common shares issued and outstanding	177.2		174.5		177.2		165.4
Diluted earnings per common share	$	0.37	$	0.27	$	0.64	$	0.42

The calculation of diluted earnings per share for the three and six months ended June 30, 2018 excluded an immaterial amount of share-based compensation awards that had an anti-dilutive effect.

Subsequent Event - Dividends Declared

In August of 2018, our Board of Directors declared a quarterly cash dividend for the third fiscal quarter of 2018 in the amount of $0.06 per share to holders of our Class A and Class B common stock. The dividend is payable to shareholders of record at the close of business on September 14, 2018, and is expected to be paid on October 8, 2018.

Share-based Compensation

3 Months Ended

Mar. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-based Compensation

SHARE-BASED COMPENSATION

We grant various equity-based awards relating to Class B Common Stock under our 2017 Omnibus Incentive Plan ("the Plan"). These awards consist of the following: restricted shares, restricted stock units ("RSUs"), performance-based restricted shares ("Performance Shares"), performance-based restricted stock units ("PSUs"), and non-qualified stock options.

The following table summarizes the components of our share-based compensation program expense:



	Three Months Ended June 30,		Six Months Ended June 30,
(in millions)	2018	2017	2018	2017
Restricted Shares and RSUs	0.9	0.6	1.6	0.6
Pre-IPO Restricted Shares	0.2	0.4	0.6	1.1
Performance Shares and PSUs	0.6	0.7	1.2	0.7
Nonqualified Stock Options	0.4	0.2	0.8	0.2
Share-based compensation expense	2.1	1.9	4.2	2.6
Related tax benefit	0.5	0.7	1.1	1.0

As of June 30, 2018, we had $15.4 million of pre-tax unrecognized compensation cost related to outstanding share-based compensation awards that is expected to be recognized over a weighted-average period of 2.8 years.

Restricted Shares and RSUs

The majority of the restricted shares and RSUs granted in 2017 and 2018 under the Plan vest ratably over a four-year period, with the first 25% of the grant vesting approximately one year after the date of grant, subject to continued employment through the vesting date or retirement eligibility. Dividend equivalents equal to dividends paid on our common shares during the vesting period are tracked and accumulated for each restricted share and RSU. The dividend equivalents are forfeitable and are distributed to participants in cash consistent with the date the awards vest.

A small portion of the restricted shares relate to a one-time 2018 grant, which vests 50% after a five-year period, with the remaining 50% vesting after a six-year period after the grant date, subject to continued employment through the vesting date. Dividend equivalents equal to dividends paid on our common shares during the vesting period are tracked and accumulated for each restricted share. The dividends equivalents are distributed to participants in cash consistent with the date the awards vest.



Restricted Shares and RSUs	Number of Awards		Weighted Average Grant Date Fair Value Per Unit
Unvested at December 31, 2017	240,016		$	19.00
Granted	226,576		26.79
Vested	(61,404	)	19.00
Forfeited	(12,093	)	19.48
Unvested at June 30, 2018	393,095		$	23.47

Prior to our IPO, we granted restricted shares of Class B Common Stock. Shares included in the pre-IPO restricted share grants vest ratably over a three-year period. Cash dividends are not paid on the unvested pre-IPO restricted shares, nor do they accumulate during the vesting period.



Pre-IPO Restricted Shares	Number of Awards		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	152,199		$	19.00
Granted	—		—
Vested	(101,643	)	19.00
Forfeited	(5,084	)	19.00
Unvested at June 30, 2018	45,472		$	19.00

Performance Shares and PSUs

Performance shares and PSUs include a three-year performance period with vesting based on attainment of threshold performance of earnings and return on capital targets. These awards cliff-vest at the end of the three year performance period, subject to continued employment through the vesting date or retirement eligibility, and payout ranges from 0%-200% for PSUs and from 0%-100% for performance shares. Dividend equivalents equal to dividends paid on our common shares during the vesting period are tracked and accumulated for each award. The dividend equivalents are forfeitable and are distributed to participants in cash consistent with the date the awards vest.



Performance Shares and PSUs	Number of Awards		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	391,541		$	19.00
Granted	281,572		26.78
Vested	—		—
Forfeited	(45,113	)	19.00
Unvested at June 30, 2018	628,000		22.49

Nonqualified Stock Options

The options granted under the Plan have an exercise price equal to the fair market value of the underlying stock at the date of grant and vest ratably over a four year period, with the first 25% of the grant becoming exercisable approximately one year after the date of grant. The options expire ten years from the date of grant.



Nonqualified Stock Options	Number of Awards		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	229,620		$	6.37
Granted	173,024		8.96
Vested	(8,410	)	6.37
Forfeited	(25,230	)	6.37
Unvested at June 30, 2018	369,004		$	7.59

Assumptions used in calculating the Black-Scholes value of options granted during 2018 were as follows:



Weighted-average Black-Scholes value	$	8.96
Black-Scholes Assumptions:
Expected term	6.25 years
Expected volatility	32.2		%
Expected dividend yield	0.9		%
Risk-free interest rate	2.8		%

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES In the ordinary course of conducting our business we become involved in certain legal matters and investigations on a number of matters, including liability claims, taxes other than income taxes, contract disputes, employment, and other litigation matters. We accrue for anticipated costs to defend and resolve matters that are probable and estimable. We believe the outcomes of these matters will not have a material impact on our business or our financial statements. At June 30, 2018, our firm commitments to purchase transportation equipment totaled approximately $213.5 million. WSL Acquisition The purchase and sale agreement related to our June 2016 acquisition of WSL included guaranteed payments of $20.0 million to the former owners of WSL on each of the first three anniversary dates of the closing. The liability recorded was discounted between one percent and three percent, based on credit-adjusted discount rates. The initial payment in the amount of $19.7 million, including calculated interest based on the discounted amount recorded, was made in June 2017 and reflected an adjustment for a working capital true-up. The second payment in the amount of $20.0 million was made in June 2018. The present value of the remaining payment was $18.7 million at June 30, 2018, which is recorded in other current liabilities on the consolidated balance sheet. The representative of the former owners of WSL has claimed that we have not fulfilled certain obligations under the purchase and sale agreement relating to the post-closing operations of the business, amongst other matters, and that, as a result, the former owners are entitled to an accelerated payment of the contingent amount described in Note 3, Fair Value, without regard to whether the specified earnings targets are met. We believe this claim is meritless and have filed an action in the Delaware Court of Chancery seeking a declaratory judgment that we have complied with our obligations under the agreement and that no accelerated payment is owed.

Segment Reporting

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

Segment Reporting

SEGMENT REPORTING

We have three reportable segments – Truckload, Intermodal, and Logistics – which are based primarily on the services each segment provides.

As of December 31, 2017 our operating segments within the Truckload reportable segment were VTL, Specialty Dedicated, and Bulk. During the second quarter of 2018, we reorganized the structure of the Truckload reportable segment, separating FTFM into its own operating segment and moving the remaining business that was previously under the Specialty Dedicated operating segment into the VTL operating segment. The Truckload reportable segment now consists of three operating segments (VTL, FTFM, and Bulk) that are aggregated because they have similar economic characteristics and meet the other aggregation criteria described in the accounting guidance for segment reporting.

The chief operating decision maker reviews revenues for each operating segment without the inclusion of fuel surcharge revenues. For segment purposes, any fuel surcharge revenues earned are recorded as a reduction of the segment’s fuel expenses. For all operating segments except FTFM, revenue is recognized upon delivery, and in-transit revenue is not reflected in segment results. Income from operations at a segment level reflects the measures presented to the chief operating decision maker for each segment.

Separate balance sheets are not prepared by segment and, as a result, assets are not separately identifiable by segment. All transactions between reporting segments are eliminated in consolidation.

The following tables summarize our segment information. Intersegment revenues were immaterial for all segments, with the exception of Other, which included revenues from insurance premiums charged to other segments for workers’ compensation, auto, and other types of insurance. Intersegment revenues included in Other revenues below were $20.7 million and $20.5 million for the three months ended June 30, 2018 and 2017, respectively, and $41.4 million and $37.4 million for the six months ended June 30, 2018 and 2017, respectively.



	Three Months Ended June 30,						Six Months Ended June 30,
Revenues by Segment (in millions)	2018			2017			2018			2017
Truckload	$	568.7		$	543.0		$	1,120.0		$	1,065.1
Intermodal	227.9			194.3			428.9			375.4
Logistics	249.7			191.7			470.5			375.6
Total revenues of reportable segments	1,046.3			929.0			2,019.4			1,816.1
Other	82.7			78.9			157.3			129.2
Fuel surcharge	133.1			92.6			250.9			182.8
Inter-segment eliminations	(25.8		)	(25.3		)	(52.3		)	(46.5		)
Operating revenues	$	1,236.3		$	1,075.2		$	2,375.3		$	2,081.6



	Three Months Ended June 30,					Six Months Ended June 30,
Income (Loss) from Operations by Segment (in millions)	2018			2017		2018			2017
Truckload	$	62.3		$	53.3	$	109.7		$	91.8
Intermodal	30.8			11.2		52.6			17.8
Logistics	10.2			6.5		17.9			11.7
Other	(11.6		)	8.0		(20.9		)	1.2
Income from operations	$	91.7		$	79.0	$	159.3		$	122.5
Other expenses (income)	$	3.4		$	4.4	6.5			10.0
Income before income taxes	$	88.3		$	74.6	$	152.8		$	112.5



	Three Months Ended June 30,				Six Months Ended June 30,
Depreciation and Amortization Expense by Segment (in millions)	2018		2017		2018		2017
Truckload	$	52.2	$	50.6	$	104.7	$	101.0
Intermodal	9.5		8.5		18.7		16.5
Logistics	0.1		0.1		0.2		0.2
Other	10.1		9.4		20.0		18.8
Depreciation and amortization expense	$	71.9	$	68.6	$	143.6	$	136.5

General (Policies)	6 Months Ended
General (Policies)	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business In this report, when we refer to “the Company,” “us,” “we,” “our,” or “ours,” we are referring to Schneider National, Inc. and its subsidiaries. We are a leading transportation services organization headquartered in Green Bay, Wisconsin. We provide a broad portfolio of premier truckload, intermodal, and logistics solutions and operate one of the largest trucking fleets in North America.
Basis of Presentation	Basis of Presentation The accompanying unaudited interim Consolidated Financial Statements have been prepared in accordance with GAAP and the rules and regulations of the SEC applicable to quarterly reports on Form 10-Q. Therefore, these financial statements and footnotes do not include all disclosures required by GAAP for annual financial statements. These financial statements should be read in conjunction with the Consolidated Financial Statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2017. Financial results for an interim period are not necessarily indicative of the results for a full year. All intercompany transactions have been eliminated in consolidation. In the opinion of management, these statements reflect all adjustments (consisting only of normal recurring adjustments) necessary for the fair presentation of our financial results for the interim periods presented.
Accounting Standards Issued But Not Yet Adopted	Accounting Standards Issued But Not Yet Adopted In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income, which discusses the reclassification of certain tax effects from accumulated other comprehensive income. The guidance requires companies to disclose a description of their accounting policy for releasing income tax effects from accumulated other comprehensive income and whether they elect to reclassify the stranded income tax effects from the Tax Cuts and Jobs Act, along with information about other income tax effects that are reclassified. The guidance is effective for us as of January 1, 2019 with early adoption permitted. We plan to early adopt this guidance during the fourth quarter of 2018 and expect the reclassification of stranded income tax effects to have an immaterial impact on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases, which is codified as ASC 842. Subsequent ASUs have clarified and modified this guidance. This standard requires lessees to recognize assets and liabilities in the consolidated balance sheets for leases with lease terms of more than 12 months. Consistent with current accounting principles, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee primarily will depend on its classification as a finance or operating lease. However, unlike current accounting principles, which require only capital leases to be recognized in the consolidated balance sheets, the new ASU will require both types of leases to be recognized in the consolidated balance sheets. In transition, lessees and lessors can elect to recognize and measure leases at the date of adoption or at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that companies may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. The transition guidance also provides specific guidance for sale and leaseback transactions, build-to-suit leases, leveraged leases, and amounts previously recognized in accordance with the business combinations guidance for leases. The new standard is effective for us as of January 1, 2019 with early adoption permitted. We have formed a cross-functional implementation team that has both identified the population of the company's lease contracts affected by the new standard and selected a system to help accommodate the new leasing standard. We have not yet completed our assessment of the impact of the new guidance on our consolidated financial statements; however, we do expect an increase in our assets and liabilities from the recognition of operating leases on the consolidated balance sheets. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments, which requires companies to use a forward-looking, expected loss model to estimate credit losses on various types of financial assets and net investments in leases. It also requires additional disclosure related to credit quality of trade and other receivables, including information related to management’s estimate of credit allowances. This guidance is effective for us as of January 1, 2020. We currently cannot reasonably estimate the impact that the adoption of this ASU will have on our consolidated financial statements.

Revenue Recognition Revenue Recognition (Tables)

3 Months Ended

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Summary of Impact of Adoption of Accounting Standards [Table Text Block]

The following table shows the amount by which financial statement lines were affected by the adoption of the new standard. The changes relate to the recognition of transportation revenue over time rather than at delivery, as explained below under the Transportation heading.



	Three Months Ended June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605		Adjustment		As Reported
Consolidated Statement of Comprehensive Income
Operating revenues	$	1,231.3	$	5.0	$	1,236.3
Purchased transportation	482.7		3.0		485.7
Salaries, wages, and benefits	313.8		0.9		314.7
Total operating expenses	1,140.7		3.9		1,144.6
Income from operations	90.6		1.1		91.7
Provision for income taxes	22.2		0.3		22.5
Net income	65.0		0.8		65.8
Comprehensive Income	65.4		0.8		66.2



	Six Months Ended June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605		Adjustment		As Reported
Consolidated Statement of Comprehensive Income
Operating revenues	$	2,369.8	$	5.5	$	2,375.3
Purchased transportation	906.9		3.8		910.7
Salaries, wages, and benefits	624.8		1.2		626.0
Total operating expenses	2,211.0		5.0		2,216.0
Income from operations	158.8		0.5		159.3
Provision for income taxes	39.3		0.1		39.4
Net income	113.0		0.4		113.4
Comprehensive Income	112.8		0.4		113.2



	June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605		Adjustment		As Reported
Consolidated Balance Sheet
Prepaid expenses and other current assets	$	84.8	$	23.7	$	108.5
Total current assets	1,237.7		23.7		1,261.4
Total assets	3,469.7		23.7		3,493.4
Other current liabilities	62.7		13.6		76.3
Total current liabilities	510.0		13.6		523.6
Deferred income taxes	414.3		2.4		416.7
Total noncurrent liabilities	974.9		2.4		977.3
Retained earnings	447.4		7.7		455.1
Total shareholders' equity	1,984.8		7.7		1,992.5
Total liabilities and shareholders' equity	3,469.7		23.7		3,493.4



	Six Months Ended June 30, 2018
Financial Statement Line Item (in millions)	Under ASC 605			Adjustment			As Reported
Consolidated Statement of Cash Flows
Operating Cash Flows
Net income	$	113.0		$	0.4		$	113.4
Change in: Other assets	(12.4		)	(5.5		)	(17.9		)
Change in: Payables	36.8			0.1			36.9
Change in: Other liabilities	(21.9		)	5.0			(16.9		)

Disaggregation of Revenue [Table Text Block]

The following table breaks down our revenues by type of service, and each type of service is further described below.



	Three Months Ended June 30,				Six Months Ended June 30,
Disaggregated Revenues (in millions)	2018		2017		2018		2017
Transportation	$	1,138.0	$	979.8	$	2,187.9	$	1,915.3
Logistics management	53.9		52.5		106.0		104.8
Other	44.4		42.9		81.4		61.5
Total operating revenues	$	1,236.3	$	1,075.2	$	2,375.3	$	2,081.6

Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]



Remaining Performance Obligations (in millions)	June 30, 2018
Expected to be recognized within one year
Transportation	$	12.1
Logistics Management	10.0
Expected to be recognized after one year
Transportation	1.0
Logistics Management	4.0
Total	$	27.1

Contract with Customer, Asset and Liability [Table Text Block]

The following table provides information related to contract balances associated with our contracts with customers as of the dates shown.



Contract Balances (in millions)	June 30, 2018		January 1, 2018
Other current assets - contract assets	$	27.8	$	22.2
Other current liabilities - contract liabilities	$	1.1	$	—

Capitalized Contract Cost [Table Text Block]

The following table presents the amounts capitalized for contract fulfillment costs as of the dates shown.



(in millions)	June 30, 2018		December 31, 2017
Capitalized contract fulfillment costs	$	4.5	$	3.7

Amortization of Contract Fulfillment Costs [Table Text Block]

Amortization of capitalized contract fulfillment costs was as shown:



	Three Months Ended June 30,				Six Months Ended June 30,
(in millions)	2018		2017		2018		2017
Amortization of contract fulfillment costs	$	0.8	$	0.5	$	1.4	$	1.1

Fair Value Fair Value (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

The table below presents the carrying value of our debt portfolio along with the fair value of a fixed-rate debt portfolio with similar terms and maturities, which is based on borrowing rates available to us in the applicable year. This valuation used Level 2 inputs.



	June 30, 2018				December 31, 2017
(in millions)	Carrying Value		Fair Value		Carrying Value		Fair Value
Debt portfolio	$	416.6	$	407.0	$	429.8	$	432.4

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Investments (Tables)

6 Months Ended

Jun. 30, 2018

Investments Schedule [Abstract]

Schedule of Marketable Securities

The following table presents the values of our marketable securities as of the dates shown.



	June 30, 2018				December 31, 2017
(in millions)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Zero coupon bonds	$	3.9	$	3.9	$	3.8	$	3.9
U.S. treasury and government agencies	14.0		13.7		6.0		6.0
Asset-backed securities	0.1		0.1		0.3		0.3
Corporate debt securities	9.1		9.0		9.1		9.2
State and municipal bonds	12.7		12.5		22.7		22.2
Total marketable securities	$	39.8	$	39.2	$	41.9	$	41.6

Goodwill and Other Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Changes in Carrying Amount of Goodwill

Changes in the carrying amount of goodwill were as follows:



(in millions)	Truckload		Logistics		Other			Total
Balance at December 31, 2017	$	138.2	$	14.2	$	12.4		$	164.8
Foreign currency translation	—		—		(0.2		)	(0.2		)
Balance at June 30, 2018	$	138.2	$	14.2	$	12.2		$	164.6

Schedule of Identifiable Intangible Assets Other Than Goodwill

The identifiable intangible assets other than goodwill listed below are included in other noncurrent assets on the consolidated balance sheets.



	June 30, 2018						December 31, 2017
(in millions)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Customer lists	$	10.5	$	3.0	$	7.5	$	10.5	$	2.5	$	8.0
Trade names	1.4		1.0		0.4		1.4		0.7		0.7
Total intangible assets	$	11.9	$	4.0	$	7.9	$	11.9	$	3.2	$	8.7

Schedule of Estimated Future Amortization Expense

Estimated future amortization expense related to intangible assets is as follows (in millions):



Remaining 2018	$	0.6
2019	1.1
2020	1.0
2021	1.0
2022	1.0
2023 and thereafter	3.2
	$	7.9

Debt and Credit Facilities (Tables)

3 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

Summary of Debt

As of June 30, 2018 and December 31, 2017, debt included the following:



(in millions)	June 30, 2018			December 31, 2017
Unsecured senior notes: principal payable at maturities ranging from 2019 through 2025; interest payable in semiannual installments through the same timeframe; weighted-average interest rate of 3.36% for both 2018 and 2017	$	400.0		$	400.0
Equipment financing notes: principal and interest payable in monthly installments through 2023; weighted average interest rate of 3.80% and 3.76% for 2018 and 2017, respectively	16.6			29.8
Total principal outstanding	416.6			429.8
Current maturities	(6.3		)	(15.2		)
Debt issuance costs	(0.8		)	(0.9		)
Long-term debt	$	409.5		$	413.7

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Lease Receivables (Tables)

3 Months Ended

Mar. 31, 2018

Leases [Abstract]

Summary of Investment in Lease Receivables

As of June 30, 2018 and December 31, 2017, the investment in lease receivables was as follows:



(in millions)	June 30, 2018			December 31, 2017
Future minimum payments to be received on leases	$	140.1		$	141.2
Guaranteed residual lease values	139.7			130.7
Total minimum lease payments to be received	279.8			271.9
Unearned income	(28.5		)	(28.1		)
Net investment in leases	251.3			243.8

Current maturities of lease receivables	122.8			106.6
Less—allowance for doubtful accounts	(0.7		)	(1.7		)
Current portion of lease receivables—net of allowance	122.1			104.9

Lease receivables—noncurrent	$	129.2		$	138.9

Common Equity (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Calculation of Basic and Diluted Earnings Per Share

The following table sets forth the computation of basic and diluted earnings per share for the three and six months ended June 30, 2018 and 2017.



	Three Months Ended June 30,				Six Months Ended June 30,
(in millions, except per share data)	2018		2017		2018		2017
Basic earnings per common share:
Net income available to common shareholders	$	65.8	$	46.5	$	113.4	$	69.1
Weighted average common shares issued and outstanding	177.0		174.4		177.0		165.4
Basic earnings per common share	$	0.37	$	0.27	$	0.64	$	0.42
Diluted earnings per common share:
Net income applicable to diluted earnings per common share	$	65.8	$	46.5	$	113.4	$	69.1
Dilutive potential common shares:
Restricted share units	0.2		0.1		0.2		—
Dilutive potential common shares	0.2		0.1		0.2		—
Total diluted average common shares issued and outstanding	177.2		174.5		177.2		165.4
Diluted earnings per common share	$	0.37	$	0.27	$	0.64	$	0.42

Share-based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

The following table summarizes the components of our share-based compensation program expense:



	Three Months Ended June 30,		Six Months Ended June 30,
(in millions)	2018	2017	2018	2017
Restricted Shares and RSUs	0.9	0.6	1.6	0.6
Pre-IPO Restricted Shares	0.2	0.4	0.6	1.1
Performance Shares and PSUs	0.6	0.7	1.2	0.7
Nonqualified Stock Options	0.4	0.2	0.8	0.2
Share-based compensation expense	2.1	1.9	4.2	2.6
Related tax benefit	0.5	0.7	1.1	1.0

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]



Restricted Shares and RSUs	Number of Awards		Weighted Average Grant Date Fair Value Per Unit
Unvested at December 31, 2017	240,016		$	19.00
Granted	226,576		26.79
Vested	(61,404	)	19.00
Forfeited	(12,093	)	19.48
Unvested at June 30, 2018	393,095		$	23.47

Prior to our IPO, we granted restricted shares of Class B Common Stock. Shares included in the pre-IPO restricted share grants vest ratably over a three-year period. Cash dividends are not paid on the unvested pre-IPO restricted shares, nor do they accumulate during the vesting period.



Pre-IPO Restricted Shares	Number of Awards		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	152,199		$	19.00
Granted	—		—
Vested	(101,643	)	19.00
Forfeited	(5,084	)	19.00
Unvested at June 30, 2018	45,472		$	19.00

Share-based Compensation, Performance Shares Award Outstanding Activity [Table Text Block]



Performance Shares and PSUs	Number of Awards		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	391,541		$	19.00
Granted	281,572		26.78
Vested	—		—
Forfeited	(45,113	)	19.00
Unvested at June 30, 2018	628,000		22.49

Share-based Compensation, Stock Options, Activity [Table Text Block]



Nonqualified Stock Options	Number of Awards		Weighted Average Grant Date Fair Value
Unvested at December 31, 2017	229,620		$	6.37
Granted	173,024		8.96
Vested	(8,410	)	6.37
Forfeited	(25,230	)	6.37
Unvested at June 30, 2018	369,004		$	7.59

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

Assumptions used in calculating the Black-Scholes value of options granted during 2018 were as follows:



Weighted-average Black-Scholes value	$	8.96
Black-Scholes Assumptions:
Expected term	6.25 years
Expected volatility	32.2		%
Expected dividend yield	0.9		%
Risk-free interest rate	2.8		%

Share-based Compensation Components of Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	$ 2.1	$ 1.9	$ 4.2	$ 2.6
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	0.5	0.7	1.1	1.0
Restricted Shares And Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	0.9	0.6	1.6	0.6
Performance Shares And Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	0.6	0.7	1.2	0.7
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	0.4	0.2	0.8	0.2
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	$ 0.2	$ 0.4	$ 0.6	$ 1.1

Segment Reporting (Tables)

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

Summary of Segment Reporting Information

The following tables summarize our segment information. Intersegment revenues were immaterial for all segments, with the exception of Other, which included revenues from insurance premiums charged to other segments for workers’ compensation, auto, and other types of insurance. Intersegment revenues included in Other revenues below were $20.7 million and $20.5 million for the three months ended June 30, 2018 and 2017, respectively, and $41.4 million and $37.4 million for the six months ended June 30, 2018 and 2017, respectively.



	Three Months Ended June 30,						Six Months Ended June 30,
Revenues by Segment (in millions)	2018			2017			2018			2017
Truckload	$	568.7		$	543.0		$	1,120.0		$	1,065.1
Intermodal	227.9			194.3			428.9			375.4
Logistics	249.7			191.7			470.5			375.6
Total revenues of reportable segments	1,046.3			929.0			2,019.4			1,816.1
Other	82.7			78.9			157.3			129.2
Fuel surcharge	133.1			92.6			250.9			182.8
Inter-segment eliminations	(25.8		)	(25.3		)	(52.3		)	(46.5		)
Operating revenues	$	1,236.3		$	1,075.2		$	2,375.3		$	2,081.6



	Three Months Ended June 30,					Six Months Ended June 30,
Income (Loss) from Operations by Segment (in millions)	2018			2017		2018			2017
Truckload	$	62.3		$	53.3	$	109.7		$	91.8
Intermodal	30.8			11.2		52.6			17.8
Logistics	10.2			6.5		17.9			11.7
Other	(11.6		)	8.0		(20.9		)	1.2
Income from operations	$	91.7		$	79.0	$	159.3		$	122.5
Other expenses (income)	$	3.4		$	4.4	6.5			10.0
Income before income taxes	$	88.3		$	74.6	$	152.8		$	112.5



	Three Months Ended June 30,				Six Months Ended June 30,
Depreciation and Amortization Expense by Segment (in millions)	2018		2017		2018		2017
Truckload	$	52.2	$	50.6	$	104.7	$	101.0
Intermodal	9.5		8.5		18.7		16.5
Logistics	0.1		0.1		0.2		0.2
Other	10.1		9.4		20.0		18.8
Depreciation and amortization expense	$	71.9	$	68.6	$	143.6	$	136.5

General - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	6 Months Ended
	May 31, 2017	Jun. 30, 2018	Jun. 30, 2017
Class of Stock [Line Items]
CASH AND CASH EQUIVALENTS:		$ 0.0	$ 341.1
Class B Common Stock \| IPO
Class of Stock [Line Items]
Share issued during the period (shares)	20,145,000
Share issued, (price per share)	$ 19
Sale of Stock, Consideration Received on Transaction	$ 382.7
Expenses related to the offering	42.1
CASH AND CASH EQUIVALENTS:	$ 340.6

Revenue Recognition Summary of Impact of Adoption of Accounting Standards (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Item Effected [Line Items]
Operating revenues	$ 1,236.3	$ 1,075.2	$ 2,375.3	$ 2,081.6
Purchased transportation	485.7	387.5	910.7	754.8
Salaries, wages, and benefits	314.7	304.9	626.0	602.6
Total operating expenses	1,144.6	996.2	2,216.0	1,959.1
Income from operations	91.7	79.0	159.3	122.5
Provision for income taxes	22.5	28.1	39.4	43.4
Net income	65.8	46.5	113.4	69.1
Comprehensive Income	66.2	$ 46.0	113.2	68.6
Prepaid expenses and other current assets	108.5		108.5		$ 75.6
Total current assets	1,261.4		1,261.4		1,094.0
Total assets	3,493.4		3,493.4		3,330.5
Other current liabilities	76.3		76.3		69.6
Total current liabilities	523.6		523.6		462.0
Deferred income taxes	416.7		416.7		386.6
Total noncurrent liabilities	977.3		977.3		978.3
Retained earnings	455.1		455.1		355.6
Total shareholders' equity	1,992.5		1,992.5		1,890.2
Total liabilities and shareholders' equity	3,493.4		3,493.4		$ 3,330.5
Other Assets			(17.9)	11.8
Payables			36.9	2.0
Other Liabilities			(16.9)	$ (12.2)
Balances under ASC 605 [Member]
Item Effected [Line Items]
Operating revenues	1,231.3		2,369.8
Purchased transportation	482.7		906.9
Salaries, wages, and benefits	313.8		624.8
Total operating expenses	1,140.7		2,211.0
Income from operations	90.6		158.8
Provision for income taxes	22.2		39.3
Net income	65.0		113.0
Comprehensive Income	65.4		112.8
Prepaid expenses and other current assets	84.8		84.8
Total current assets	1,237.7		1,237.7
Total assets	3,469.7		3,469.7
Other current liabilities	62.7		62.7
Total current liabilities	510.0		510.0
Deferred income taxes	414.3		414.3
Total noncurrent liabilities	974.9		974.9
Retained earnings	447.4		447.4
Total shareholders' equity	1,984.8		1,984.8
Total liabilities and shareholders' equity	3,469.7		3,469.7
Other Assets			(12.4)
Payables			36.8
Other Liabilities			(21.9)
Effect on line items of ASC 606 [Member]
Item Effected [Line Items]
Operating revenues	5.0		5.5
Purchased transportation	3.0		3.8
Salaries, wages, and benefits	0.9		1.2
Total operating expenses	3.9		5.0
Income from operations	1.1		0.5
Provision for income taxes	0.3		0.1
Net income	0.8		0.4
Comprehensive Income	0.8		0.4
Prepaid expenses and other current assets	23.7		23.7
Total current assets	23.7		23.7
Total assets	23.7		23.7
Other current liabilities	13.6		13.6
Total current liabilities	13.6		13.6
Deferred income taxes	2.4		2.4
Total noncurrent liabilities	2.4		2.4
Retained earnings	7.7		7.7
Total shareholders' equity	7.7		7.7
Total liabilities and shareholders' equity	$ 23.7		23.7
Other Assets			(5.5)
Payables			0.1
Other Liabilities			$ 5.0

Revenue Recognition Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
OPERATING REVENUES	$ 1,236.3	$ 1,075.2	$ 2,375.3	$ 2,081.6
Transportation [Member]
Disaggregation of Revenue [Line Items]
OPERATING REVENUES	1,138.0	979.8	2,187.9	1,915.3
Logistics Management [Member]
Disaggregation of Revenue [Line Items]
OPERATING REVENUES	53.9	52.5	106.0	104.8
Other [Member]
Disaggregation of Revenue [Line Items]
OPERATING REVENUES	$ 44.4	$ 42.9	$ 81.4	$ 61.5

Revenue Recognition Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Details) $ in Millions	Jun. 30, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 27.1
Expected to be recongized within one year [Member] \| Transportation [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	12.1
Expected to be recongized within one year [Member] \| Logistics Management [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	10.0
Expected to be recognized after one year [Member] \| Transportation [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	1.0
Expected to be recognized after one year [Member] \| Logistics Management [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 4.0

Revenue Recognition Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	Jun. 30, 2018	Jan. 01, 2018
Contract Balances [Line Items]
Contract with Customer, Asset, Net	$ 27.8	$ 22.2
Contract with Customer, Liability	$ 1.1	$ 0.0

Revenue Recognition Capitalized Contract Cost (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost	$ 4.5	$ 3.7

Revenue Recognition Amortization of Contract Fulfillment Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Capitalized Contract Cost, Amortization [Line Items]
Capitalized Contract Cost, Amortization	$ 0.8	$ 0.5	$ 1.4	$ 1.1

Revenue Recognition Initial Application Period Cumulative Effect Adjustment (Details) $ in Millions	Jan. 01, 2018 USD ($)
Initial Application Period Cumulative Translation Adjustment [Abstract]
Cumulative Effect on Retained Earnings, Net of Tax	$ 7.3

Fair Value Fair Value - Additional Information (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Transfers Between Levels Transfers Amount	$ 0	$ 0
Fair Value, Inputs, Level 3 [Member] \| Watkins and Shepard Trucking Inc [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			$ 40,000,000
Business Combination, Contingent Consideration, Liability, Fair Value	$ 0	$ 0

Fair Value Fair value of debt portfolio (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Amount	$ 416.6	$ 429.8
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Amount	$ 407.0	$ 432.4

Investments (Details)	6 Months Ended
Investments (Details)	Jun. 30, 2018
Minimum
Debt Securities, Available-for-sale [Line Items]
Marketable securities maturity term	3 months
Maximum
Debt Securities, Available-for-sale [Line Items]
Marketable securities maturity term	72 months

Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 39.8	$ 41.9
Fair Value	39.2	41.6
Current Asset \| Zero coupon bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3.9	3.8
Fair Value	3.9	3.9
Current Asset \| U.S. treasury and government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	14.0	6.0
Fair Value	13.7	6.0
Current Asset \| Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0.1	0.3
Fair Value	0.1	0.3
Current Asset \| Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9.1	9.1
Fair Value	9.0	9.2
Current Asset \| State and municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12.7	22.7
Fair Value	$ 12.5	$ 22.2

Investments Investment in Platform Science, Inc. (Details)	Jun. 30, 2018 USD ($)
Other Investments [Abstract]
Noncontrolling Interest, Ownership Percentage by Parent	30.00%
Cost Method Investments, Fair Value Disclosure	$ 2.5

Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Goodwill
Beginning balance	$ 164.8
Foreign currency translation	(0.2)
Ending balance	164.6
Truckload
Goodwill
Beginning balance	138.2
Foreign currency translation	0.0
Ending balance	138.2
Logistics
Goodwill
Beginning balance	14.2
Foreign currency translation	0.0
Ending balance	14.2
Other
Goodwill
Beginning balance	12.4
Foreign currency translation	(0.2)
Ending balance	$ 12.2

Goodwill and Other Intangible Assets - Schedule of Identifiable Intangible Assets Other Than Goodwill (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 7.9
Other Noncurrent Assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	11.9	$ 11.9
Accumulated Amortization	4.0	3.2
Net Carrying Amount	7.9	8.7
Other Noncurrent Assets \| Customer lists
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10.5	10.5
Accumulated Amortization	3.0	2.5
Net Carrying Amount	7.5	8.0
Other Noncurrent Assets \| Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1.4	1.4
Accumulated Amortization	1.0	0.7
Net Carrying Amount	$ 0.4	$ 0.7

Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense for intangible assets	$ 0.4	$ 0.4	$ 0.7	$ 0.8
Goodwill, Impaired, Accumulated Impairment Loss	$ 6.0		$ 6.0		$ 6.0

Goodwill and Other Intangible Assets - Schedule Estimated Future Amortization Expense (Details) $ in Millions	Jun. 30, 2018 USD ($)
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule
Remaining 2018	$ 0.6
2018	1.1
2019	1.0
2020	1.0
2021	1.0
2023 and thereafter	3.2
Net Carrying Amount	$ 7.9

Debt and Credit Facilities - Summary of Debt (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total principal outstanding	$ 416.6	$ 429.8
Current maturities	(6.3)	(15.2)
Debt issuance costs	(0.8)	(0.9)
Long-term debt	$ 409.5	413.7
Unsecured Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Frequency of Periodic Payment	Semiannual
Total principal outstanding	$ 400.0	$ 400.0
Maturity year	2025	2025
Weighted-average interest rate	3.36%	3.36%
Equipment Financing Notes
Debt Instrument [Line Items]
Debt Instrument, Frequency of Periodic Payment	Monthly
Total principal outstanding	$ 16.6	$ 29.8
Maturity year	2023	2023
Weighted-average interest rate	3.80%	3.76%
Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Expiration Date	Nov. 30, 2018
Secured Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Expiration Date	Sep. 30, 2018

Debt and Credit Facilities - Additional Information (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total principal outstanding	$ 416,600,000	$ 429,800,000
Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Credit Facility, Maximum Borrowing Capacity	$ 250.0
Credit Facility, Expiration Date	Nov. 30, 2018
Credit facility, Outstanding borrowings	$ 0	0
Revolving Credit Agreement [Member] \| Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Credit Facility, Maximum Borrowing Capacity	100.0
Credit facility, Standby letters of credit	3,900,000	3,900,000
Secured Credit Facility
Debt Instrument [Line Items]
Credit Facility, Maximum Borrowing Capacity	$ 200.0
Credit Facility, Expiration Date	Sep. 30, 2018
Credit facility, Outstanding borrowings	$ 0	0
Secured Credit Facility \| Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Credit facility, Standby letters of credit	$ 62,800,000	$ 63,800,000

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References + Details

Lease Receivables - Summary of Investment in Lease Receivables (Details) - USD ($) $ in Millions	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Future minimum payments to be received on leases		$ 140.1	$ 141.2
Guaranteed residual lease values		139.7	130.7
Total minimum lease payments to be received		279.8	271.9
Unearned income		(28.5)	(28.1)
Net investment in leases		251.3	243.8
Current maturities of lease receivables		122.8	106.6
Less—allowance for doubtful accounts		(0.7)	(1.7)
Current portion of lease receivables—net of allowance	$ 122.1	122.1	104.9
Lease receivables—noncurrent		$ 129.2	$ 138.9
Minimum [Member]
Operating Leased Assets [Line Items]
Lessor, Direct Financing Lease, Term of Contract	1 year
Maximum [Member]
Operating Leased Assets [Line Items]
Lessor, Direct Financing Lease, Term of Contract	5 years

Income Taxes - Additional Information (Details)	3 Months Ended		6 Months Ended
Income Taxes - Additional Information (Details)	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	25.50%	37.70%	25.80%	38.60%

Common Equity - Calculation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic earnings per common share:
Net income available to common shareholders	$ 65.8	$ 46.5	$ 113.4	$ 69.1
Weighted average common shares issued and outstanding	177.0	174.4	177.0	165.4
Basic earnings per common share	$ 0.37	$ 0.27	$ 0.64	$ 0.42
Diluted earnings per common share:
Net income applicable to diluted earnings per common share	$ 65.8	$ 46.5	$ 113.4	$ 69.1
Dilutive potential common shares:
Restricted share units	0.2	0.1	0.2	0.0
Dilutive potential common shares	0.2	0.1	0.2	0.0
Dilutive potential common shares	177.2	174.5	177.2	165.4
Diluted earnings per common share	$ 0.37	$ 0.27	$ 0.64	$ 0.42

Common Equity - Additional Information (Details) - $ / shares	3 Months Ended			6 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Class of Stock [Line Items]
Dividends declared per share (usd per share)		$ 0.06	$ 0.05	$ 0.12	$ 0.1
Subsequent Event \| Class A Common Shares
Class of Stock [Line Items]
Dividends declared per share (usd per share)	$ 0.06

Share-based Compensation Restricted Shares and RSUs (Details) - $ / shares	3 Months Ended	6 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Restricted Shares And Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 23.47	$ 19.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		26.79
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		19.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 19.48
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, Grants in Period		226,576
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(61,404)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		393,095	240,016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(12,093)
Share-based Compensation Award, Tranche One [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Share-based Compensation Award, Tranche One [Member] \| Restricted Shares And Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
Share-based Compensation Award, Tranche Two [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	6 years
Pre-IPO Share-Based Compensation Plan [Member] \| Restricted Shares And Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 19.00	$ 19.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		0.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		19.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 19.00
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, Grants in Period		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(101,643)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		45,472	152,199
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(5,084)

Share-based Compensation Performance Shares and PSUs (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Performance Shares And Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Performance Period	3 years
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, Grants in Period	281,572
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(45,113)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	628,000	391,541
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 26.78
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	0.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	19.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 22.49	$ 19.00
PSU [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement By Share-based Payment Award, Payout Range, Percentage	200.00%
Performance Shares [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement By Share-based Payment Award, Payout Range, Percentage	0.00%
Performance Shares [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement By Share-based Payment Award, Payout Range, Percentage	100.00%

Share-based Compensation Nonqualified Stock Options (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	173,024
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	(8,410)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares	369,004	229,620
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price	$ 7.59	$ 6.37
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	8.96
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value	$ 6.37
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	25,230
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value	$ 6.37
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 8.96
Employee Stock Option [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%

Share-based Compensation Stock Option Valuation Assumptions (Details)	3 Months Ended
	Mar. 31, 2018 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price	$ 8.96
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price	$ 8.96
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 years 3 months
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	32.20%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.90%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.80%

Share-based Compensation Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 15.4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 9 months

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018
Business Acquisition [Line Items]
Commitments to purchase transportation equipment	$ 213.5		$ 213.5
WSL
Business Acquisition [Line Items]
Initial guaranteed payment		$ 19.7
Second Guaranteed Payment	20.0
Business Combination Consideration Transferred Guaranteed Payment	$ 18.7		18.7
Former Owner [Member]
Business Acquisition [Line Items]
Cash payments			$ 20.0
Former Owner [Member] \| Minimum
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Discounted Cash Flow Discount Rate			1.00%
Former Owner [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Discounted Cash Flow Discount Rate			3.00%

Segment Reporting - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Segment	Jun. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments \| Segment			3
Number of operating segments			3
Operating revenues	$ 1,236.3	$ 1,075.2	$ 2,375.3	$ 2,081.6
Other
Segment Reporting Information [Line Items]
Operating revenues	82.7	78.9	157.3	129.2
Other \| Other Insurance
Segment Reporting Information [Line Items]
Operating revenues	$ 20.7	$ 20.5	$ 41.4	$ 37.4

Segment Reporting - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Operating revenues	$ 1,236.3	$ 1,075.2	$ 2,375.3	$ 2,081.6
Revenues excluding fuel surcharge	1,046.3	929.0	2,019.4	1,816.1
Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(25.8)	(25.3)	(52.3)	(46.5)
Truckload
Segment Reporting Information [Line Items]
Revenues excluding fuel surcharge	568.7	543.0	1,120.0	1,065.1
Intermodal
Segment Reporting Information [Line Items]
Revenues excluding fuel surcharge	227.9	194.3	428.9	375.4
Logistics
Segment Reporting Information [Line Items]
Revenues excluding fuel surcharge	249.7	191.7	470.5	375.6
Other
Segment Reporting Information [Line Items]
Operating revenues	82.7	78.9	157.3	129.2
Fuel Surcharge
Segment Reporting Information [Line Items]
Operating revenues	$ 133.1	$ 92.6	$ 250.9	$ 182.8

Segment Reporting - Income From Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Income from operations	$ 91.7	$ 79.0	$ 159.3	$ 122.5
Nonoperating Income (Expense)	(3.4)	(4.4)	(6.5)	(10.0)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	88.3	74.6	152.8	112.5
Truckload
Segment Reporting Information [Line Items]
Income from operations	62.3	53.3	109.7	91.8
Intermodal
Segment Reporting Information [Line Items]
Income from operations	30.8	11.2	52.6	17.8
Logistics
Segment Reporting Information [Line Items]
Income from operations	10.2	6.5	17.9	11.7
Other
Segment Reporting Information [Line Items]
Income from operations	$ (11.6)	$ 8.0	$ (20.9)	$ 1.2

Segment Reporting - Depreciation and Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Depreciation and amortization expense	$ 71.9	$ 68.6	$ 143.6	$ 136.5
Truckload
Segment Reporting Information [Line Items]
Depreciation and amortization expense	52.2	50.6	104.7	101.0
Intermodal
Segment Reporting Information [Line Items]
Depreciation and amortization expense	9.5	8.5	18.7	16.5
Logistics
Segment Reporting Information [Line Items]
Depreciation and amortization expense	0.1	0.1	0.2	0.2
Other
Segment Reporting Information [Line Items]
Depreciation and amortization expense	$ 10.1	$ 9.4	$ 20.0	$ 18.8