ATMOS ENERGY CORP, 10-Q filed on 2/4/2025
Quarterly Report
v3.25.0.1
Cover Page - shares
 3 Months Ended
Dec. 31, 2024
Jan. 31, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Dec. 31, 2024  
Document Transition Report false  
Entity File Number 1-10042  
Entity Registrant Name Atmos Energy Corp  
Entity Incorporation, State or Country Code TX  
Entity Tax Identification Number 75-1743247  
Entity Address, Address Line One 1800 Three Lincoln Centre  
Entity Address, Address Line Two 5430 LBJ Freeway  
Entity Address, City or Town Dallas  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 75240  
City Area Code 972  
Local Phone Number 934-9227  
Title of 12(b) Security Common stock  
Trading Symbol ATO  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding (in shares)   158,728,197
Entity Central Index Key 0000731802  
Current Fiscal Year End Date --09-30  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q1  
Amendment Flag false  
v3.25.0.1
CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
ASSETS    
Property, plant and equipment $ 26,675,943 $ 25,848,083
Less accumulated depreciation and amortization 3,713,900 3,643,716
Net property, plant and equipment 22,962,043 22,204,367
Current assets    
Cash and cash equivalents 584,536 307,340
Restricted cash and cash equivalents 4,870 1,516
Cash and cash equivalents and restricted cash and cash equivalents 589,406 308,856
Accounts receivable, net 628,871 365,882
Gas stored underground 153,034 169,508
Other current assets 456,816 288,068
Total current assets 1,828,127 1,132,314
Securitized intangible asset, net (See Note 9) 80,580 82,844
Goodwill 731,257 731,257
Deferred charges and other assets 895,086 1,043,683
Total assets 26,497,093 25,194,465
Shareholders’ equity    
Common stock, no par value (stated at $0.005 per share); 200,000,000 shares authorized; issued and outstanding: December 31, 2024 — 158,726,065 shares; September 30, 2024 — 155,258,845 shares 794 776
Additional paid-in capital 7,864,525 7,474,559
Accumulated other comprehensive income 482,138 465,715
Retained earnings 4,433,024 4,216,619
Shareholders’ equity 12,780,481 12,157,669
Long-term debt, net 8,413,374 7,783,646
Securitized long-term debt (See Note 9) 76,871 76,871
Total capitalization 21,270,726 20,018,186
Current liabilities    
Accounts payable and accrued liabilities 453,045 445,397
Other current liabilities 701,915 750,620
Current maturities of long-term debt 11,681 1,651
Current maturities of securitized long-term debt (See Note 9) 8,207 8,207
Total current liabilities 1,174,848 1,205,875
Deferred income taxes 2,674,678 2,593,342
Regulatory excess deferred taxes 173,001 177,315
Regulatory cost of removal obligation 520,190 507,815
Deferred credits and other liabilities 683,650 691,932
Total capitalization and liabilities $ 26,497,093 $ 25,194,465
v3.25.0.1
CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares
Dec. 31, 2024
Sep. 30, 2024
Statement of Financial Position [Abstract]    
Common stock stated value (USD per share) $ 0.005 $ 0.005
Common stock authorized (in shares) 200,000,000 200,000,000
Common stock issued (in shares) 158,726,065 155,258,845
Common stock outstanding (in shares) 158,726,065 155,258,845
v3.25.0.1
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
shares in Thousands, $ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Operating revenues $ 1,175,999 $ 1,158,467
Purchased gas cost 234,048 338,869
Operation and maintenance expense 207,044 166,345
Depreciation and amortization expense 180,533 164,608
Taxes, other than income 94,894 89,540
Operating income 459,480 399,105
Other non-operating income 24,634 17,886
Interest charges 52,925 51,875
Income before income taxes 431,189 365,116
Income tax expense 79,331 53,824
Net income $ 351,858 $ 311,292
Basic net income per share (USD per share) $ 2.25 $ 2.08
Diluted net income per share (USD per share) 2.23 2.08
Cash dividends per share (USD per share) $ 0.870 $ 0.805
Basic weighted average shares outstanding (in shares) 156,301 149,796
Diluted weighted average shares outstanding (in shares) 157,824 149,796
Other comprehensive income (loss), net of tax    
Net unrealized holding gains (losses) on available-for-sale securities, net of tax of $(42) and $86 $ (138) $ 296
Cash flow hedges:    
Amortization and unrealized gains (losses) on interest rate agreements, net of tax of $3,492 and $(14,519) 16,561 (50,232)
Total other comprehensive income (loss) 16,423 (49,936)
Total comprehensive income 368,281 261,356
Distribution segment    
Operating revenues 1,108,569 1,104,619
Pipeline and storage segment    
Operating revenues 67,430 53,848
Operating Segments | Distribution segment    
Operating revenues 1,109,335 1,105,338
Purchased gas cost 422,570 496,662
Operation and maintenance expense 154,514 127,615
Depreciation and amortization expense 133,627 119,685
Taxes, other than income 82,576 80,895
Operating income 316,048 280,481
Other non-operating income 10,084 5,839
Interest charges 34,249 34,581
Income before income taxes 291,883 251,739
Income tax expense 51,670 30,302
Net income 240,213 221,437
Operating Segments | Pipeline and storage segment    
Operating revenues 255,390 211,169
Purchased gas cost (58) 4
Operation and maintenance expense 52,792 38,973
Depreciation and amortization expense 46,906 44,923
Taxes, other than income 12,318 8,645
Operating income 143,432 118,624
Other non-operating income 14,550 12,047
Interest charges 18,676 17,294
Income before income taxes 139,306 113,377
Income tax expense 27,661 23,522
Net income 111,645 89,855
Intersegment eliminations    
Operating revenues (188,726) (158,040)
Purchased gas cost (188,464) (157,797)
Operation and maintenance expense (262) (243)
Depreciation and amortization expense 0 0
Taxes, other than income 0 0
Operating income 0 0
Other non-operating income 0 0
Interest charges 0 0
Income before income taxes 0 0
Income tax expense 0 0
Net income 0 0
Intersegment eliminations | Distribution segment    
Operating revenues (766) (719)
Intersegment eliminations | Pipeline and storage segment    
Operating revenues $ (187,960) $ (157,321)
v3.25.0.1
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Income Statement [Abstract]    
Net unrealized holding gains (losses) on available-for-sale securities, tax $ (42) $ 86
Amortization and unrealized gains (losses) on interest rate agreements, net $ 3,492 $ (14,519)
v3.25.0.1
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Cash Flows From Operating Activities    
Net income $ 351,858 $ 311,292
Adjustments to reconcile net income to net cash provided by operating activities:    
Depreciation and amortization expense 180,533 164,608
Deferred income taxes 71,107 44,108
Other (19,279) (16,839)
Net assets / liabilities from risk management activities 1,891 5,589
Net change in other operating assets and liabilities (304,088) (263,478)
Net cash provided by operating activities 282,022 245,280
Cash Flows From Investing Activities    
Capital expenditures (891,191) (769,650)
Debt and equity securities activities, net (490) (78)
Other, net 2,740 5,353
Net cash used in investing activities (888,941) (764,375)
Cash Flows From Financing Activities    
Net decrease in short-term debt 0 (241,933)
Net proceeds from equity issuances 379,490 254,022
Issuance of common stock through stock purchase and employee retirement plans 4,047 3,746
Proceeds from issuance of long-term debt 645,372 898,275
Cash dividends paid (135,453) (119,898)
Debt issuance costs (5,987) (8,920)
Net cash provided by financing activities 887,469 785,292
Net increase in cash and cash equivalents and restricted cash and cash equivalents 280,550 266,197
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period 308,856 19,248
Cash and cash equivalents and restricted cash and cash equivalents at end of period $ 589,406 $ 285,445
v3.25.0.1
Nature of Business
 3 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Nature of Business Nature of Business
Atmos Energy Corporation (“Atmos Energy” or the “Company”) and its subsidiaries are engaged in the regulated natural gas distribution and pipeline and storage businesses. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our regulated divisions and subsidiaries operate.
Our distribution business delivers natural gas through sales and transportation arrangements to over 3.3 million residential, commercial, public authority, and industrial customers through our six regulated distribution divisions, which at December 31, 2024, covered service areas located in eight states.
Our pipeline and storage business, which is also subject to federal and state regulations, includes the transportation of natural gas to our Texas and Louisiana distribution systems and the management of our underground storage facilities used to support our distribution business in various states.
v3.25.0.1
Summary of Significant Accounting Policies
 3 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]  
Summary of Significant Accounting Policies Summary of Significant Accounting Policies
Basis of Presentation
These consolidated interim-period financial statements have been prepared in accordance with accounting principles generally accepted in the United States on the same basis as those used for the Company’s audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. In the opinion of management, all material adjustments (consisting of normal recurring accruals) necessary for a fair presentation have been made to the unaudited consolidated interim-period financial statements. These consolidated interim-period financial statements are condensed as permitted by the instructions to Form 10-Q and should be read in conjunction with the audited consolidated financial statements of Atmos Energy Corporation included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. Because of seasonal and other factors, the results of operations for the three-month period ended December 31, 2024 are not indicative of our results of operations for the full 2025 fiscal year, which ends September 30, 2025.
Significant accounting policies
Our accounting policies are described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024.
No events have occurred subsequent to the balance sheet date that would require recognition or disclosure in the condensed consolidated financial statements.
Recently issued accounting pronouncements
In November 2023, the Financial Accounting Standards Board (FASB) issued guidance which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. The amendment is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted, and the amendments should be applied retrospectively. This amendment will be effective for our Form 10-K for fiscal 2025 and our Form 10-Q for the first quarter of fiscal 2026. We are currently evaluating the impact this may have on our financial statement disclosures.
In December 2023, the FASB issued guidance which provides qualitative and quantitative updates to the rate reconciliation and income taxes paid disclosures, among others, in order to enhance the transparency of income tax disclosures, including consistent categories and greater disaggregation of information in the rate reconciliation and disaggregation by jurisdiction of income taxes paid. The amendment is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The amendments should be applied prospectively; however, retrospective application is also permitted. This amendment will be effective for our Form 10-K for fiscal 2026. We are currently evaluating the impact this amendment may have on our financial statement disclosures.
In November 2024, the FASB issued guidance that will require more detailed information about the types of expenses in commonly presented expense captions. The amendment is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. This amendment will be effective for our Form 10-K for fiscal 2028 and our Form 10-Q for the first quarter of fiscal 2029. We are currently evaluating the impact this may have on our financial statement disclosures.
v3.25.0.1
Regulation
 3 Months Ended
Dec. 31, 2024
Regulated Operations [Abstract]  
Regulation Regulation
Accounting principles generally accepted in the United States require cost-based, rate-regulated entities that meet certain criteria to reflect the authorized recovery of costs due to regulatory decisions in their financial statements. As a result, certain costs are permitted to be capitalized rather than expensed because they can be recovered through rates. We record certain costs as regulatory assets when future recovery through customer rates is considered probable. Regulatory liabilities are recorded when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process. Substantially all of our regulatory assets are recorded as a component of other current assets and deferred charges and other assets and our regulatory liabilities are recorded as a component of other current liabilities and deferred credits and other liabilities. Deferred gas costs are recorded either in other current assets or liabilities.
Regulatory assets and liabilities as of December 31, 2024 and September 30, 2024 included the following:
December 31,
2024		September 30,
2024
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$7,885 $11,243 
Infrastructure mechanisms (1)
189,939 246,734 
Winter Storm Uri incremental costs8,834 10,373 
Deferred gas costs169,203 159,762 
Regulatory excess deferred taxes (2)
50,941 51,380 
Recoverable loss on reacquired debt3,028 3,070 
Deferred pipeline record collection costs41,245 41,742 
APT annual System Safety and Integrity Rider (3)
35,290 38,632 
Other16,151 16,454 
$522,516 $579,390 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$249,790 $257,001 
Regulatory cost of removal obligation615,371 607,032 
Deferred gas costs3,731 9,142 
APT annual adjustment mechanism76,418 73,119 
Pension and postretirement benefit costs241,816 247,250 
Other36,282 34,338 
$1,223,408 $1,227,882 
 
(1)Infrastructure mechanisms in Texas, Louisiana, and Tennessee allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recoverable through base rates.
(2)Regulatory excess deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of Tax Cuts and Jobs Act of 2017 (the "TCJA"), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. See Note 12 to the condensed consolidated financial statements for further information.
(3)In APT's general rate case settlement in December 2023, the RRC approved a new annual compliance filing that allows APT to recover certain system safety and integrity costs incurred each year. Costs above a specified benchmark are deferred onto the balance sheet as incurred. Once the filing is approved by the RRC, the revenue and expense are recognized over 12 months resulting in no impact to operating income.
We deferred $32.4 million in carrying costs incurred after September 1, 2022 associated with interim financing for gas costs incurred in February 2021 during Winter Storm Uri. During fiscal 2024, we recovered $22.0 million of this amount. During the first quarter of fiscal 2025, we have recovered $1.6 million of this amount. Of the remaining $8.8 million, $2.4 million has been recorded as a current asset in other current assets as of December 31, 2024 and $6.4 million has been recorded as a long-term asset in deferred charges and other assets as of December 31, 2024 as we anticipate recovering this amount in future regulatory proceedings.
v3.25.0.1
Segment Information
 3 Months Ended
Dec. 31, 2024
Segment Reporting [Abstract]  
Segment Information Segment Information
We manage and review our consolidated operations through the following reportable segments:

•The distribution segment is comprised of our regulated natural gas distribution and related sales operations in eight states.
•The pipeline and storage segment is comprised primarily of the regulated pipeline and storage operations of our Atmos Pipeline-Texas division and our natural gas transmission operations in Louisiana.
The accounting policies of the segments are the same as those described in the summary of significant accounting policies found in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024.
Income statements and capital expenditures for the three months ended December 31, 2024 and 2023 by segment are presented in the following tables:
 Three Months Ended December 31, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$1,108,569 $67,430 $— $1,175,999 
Intersegment revenues766 187,960 (188,726)— 
Total operating revenues1,109,335 255,390 (188,726)1,175,999 
Purchased gas cost
422,570 (58)(188,464)234,048 
Operation and maintenance expense154,514 52,792 (262)207,044 
Depreciation and amortization expense133,627 46,906 — 180,533 
Taxes, other than income82,576 12,318 — 94,894 
Operating income316,048 143,432 — 459,480 
Other non-operating income10,084 14,550 — 24,634 
Interest charges34,249 18,676 — 52,925 
Income before income taxes
291,883 139,306 — 431,189 
Income tax expense51,670 27,661 — 79,331 
Net income$240,213 $111,645 $— $351,858 
Capital expenditures$625,649 $265,542 $— $891,191 
 Three Months Ended December 31, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$1,104,619 $53,848 $— $1,158,467 
Intersegment revenues719 157,321 (158,040)— 
Total operating revenues1,105,338 211,169 (158,040)1,158,467 
Purchased gas cost
496,662 4 (157,797)338,869 
Operation and maintenance expense127,615 38,973 (243)166,345 
Depreciation and amortization expense119,685 44,923 — 164,608 
Taxes, other than income80,895 8,645 — 89,540 
Operating income280,481 118,624 — 399,105 
Other non-operating income5,839 12,047 — 17,886 
Interest charges34,581 17,294 — 51,875 
Income before income taxes
251,739 113,377 — 365,116 
Income tax expense30,302 23,522 — 53,824 
Net income$221,437 $89,855 $— $311,292 
Capital expenditures$539,158 $230,492 $— $769,650 

Balance sheet information at December 31, 2024 and September 30, 2024 by segment is presented in the following tables:
 December 31, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$16,942,174 $6,019,869 $— $22,962,043 
Total assets$25,623,410 $6,341,439 $(5,467,756)$26,497,093 
 September 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$16,372,659 $5,831,708 $— $22,204,367 
Total assets$24,328,877 $6,181,558 $(5,315,970)$25,194,465 
v3.25.0.1
Earnings Per Share
 3 Months Ended
Dec. 31, 2024
Earnings Per Share [Abstract]  
Earnings Per Share Earnings Per Share
We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock. Additionally, the weighted average shares outstanding for diluted EPS includes the incremental effects of the forward sale agreements, discussed in Note 8 to the condensed consolidated financial statements, when the impact is dilutive.
Basic and diluted earnings per share for the three months ended December 31, 2024 and 2023 are calculated as follows:
 Three Months Ended December 31
 20242023
 (In thousands, except per share amounts)
Basic Earnings Per Share
Net income$351,858 $311,292 
Less: Income allocated to participating securities
159 186 
Income available to common shareholders
$351,699 $311,106 
Basic weighted average shares outstanding
156,301 149,796 
Net income per share — Basic
$2.25 $2.08 
Diluted Earnings Per Share
Income available to common shareholders$351,699 $311,106 
Effect of dilutive shares
— — 
Income available to common shareholders
$351,699 $311,106 
Basic weighted average shares outstanding
156,301 149,796 
Dilutive shares1,523 — 
Diluted weighted average shares outstanding
157,824 149,796 
Net income per share — Diluted$2.23 $2.08 
v3.25.0.1
Revenue and Accounts Receivable
 3 Months Ended
Dec. 31, 2024
Revenue from Contract with Customer [Abstract]  
Revenue and Accounts Receivable Revenue and Accounts Receivable
Revenue
Our revenue recognition policy is fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. The following tables disaggregate our revenue from contracts with customers by customer type and segment and provide a reconciliation to total operating revenues, including intersegment revenues, for the three months ended December 31, 2024 and 2023.
Three Months Ended December 31, 2024Three Months Ended December 31, 2023
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$693,050 $— $727,682 $— 
Commercial266,054 — 277,253 — 
Industrial26,321 — 28,231 — 
Public authority and other12,881 — 14,584 — 
Total gas sales revenues998,306 — 1,047,750 — 
Transportation revenues36,727 266,029 33,767 215,305 
Miscellaneous revenues3,022 2,664 2,643 3,042 
Revenues from contracts with customers1,038,055 268,693 1,084,160 218,347 
Alternative revenue program revenues67,336 (13,303)17,401 (7,178)
Other revenues3,944 — 3,777 — 
Total operating revenues$1,109,335 $255,390 $1,105,338 $211,169 
We have alternative revenue programs in each of our segments. In our distribution segment, we have weather-normalization adjustment mechanisms that serve to mitigate the effects of weather on our revenue. In our pipeline and storage segment, APT has a regulatory mechanism that requires that we share with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a revenue benchmark established by the RRC. Other revenues includes AEK revenues (see Note 9 to the condensed consolidated financial statements) and other miscellaneous revenues.
Accounts receivable and allowance for uncollectible accounts
Accounts receivable arise from natural gas sales to residential, commercial, industrial, public authority, and other customers. Our accounts receivable balance includes unbilled amounts which represent a customer’s consumption of gas from the date of the last cycle billing through the last day of the month. Our policy related to the accounting for our accounts receivable and allowance for uncollectible accounts is fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. During the three months ended December 31, 2024, there were no material changes to this policy. Rollforwards of our allowance for uncollectible accounts for the three months ended December 31, 2024 and 2023 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 89 percent of our customers as we have the ability to collect these gas costs through our gas cost recovery mechanisms in most of our jurisdictions.
In December 2023, the Mississippi Public Service Commission approved the recovery of uncollectible accounts through our purchased gas cost mechanism over a two-year period rather than through our annual filing mechanism over a one-year period. As a result of this decision, we recorded a $13.9 million reduction to bad debt expense during the first quarter of fiscal 2024. Of this amount, $9.7 million represents future recovery of customer receivables previously written off since April 2022 but not yet recovered through our rates. This amount increased our deferred gas cost regulatory asset. The remaining $4.2 million reduction represents a reversal of our allowance for uncollectible accounts for customer balances that have not yet been written off.
 Three Months Ended December 31, 2024
 (In thousands)
Beginning balance, September 30, 2024$37,056 
Current period provisions8,623 
Write-offs charged against allowance(7,447)
Recoveries of amounts previously written off934 
Ending balance, December 31, 2024
$39,166 
 Three Months Ended December 31, 2023
 (In thousands)
Beginning balance, September 30, 2023$40,840 
Current period provisions6,750 
Write-offs charged against allowance(8,757)
Recoveries of amounts previously written off765 
Mississippi recovery of uncollectible accounts(4,192)
Ending balance, December 31, 2023
$35,406 
v3.25.0.1
Debt
 3 Months Ended
Dec. 31, 2024
Debt Disclosure [Abstract]  
Debt Debt
The nature and terms of our debt instruments and credit facilities are described in detail in Note 8 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. Other than as described below, there were no material changes in the terms of our debt instruments during the three months ended December 31, 2024.
Long-term debt at December 31, 2024 and September 30, 2024 consisted of the following:
December 31, 2024September 30, 2024
 (In thousands)
Unsecured 3.00% Senior Notes, due June 2027
$500,000 $500,000 
Unsecured 2.625% Senior Notes, due September 2029
500,000 500,000 
Unsecured 1.50% Senior Notes, due January 2031
600,000 600,000 
Unsecured 5.45% Senior Notes, due October 2032
300,000 300,000 
Unsecured 5.90% Senior Notes, due November 2033

725,000 725,000 
Unsecured 5.95% Senior Notes, due October 2034
200,000 200,000 
Unsecured 5.50% Senior Notes, due June 2041
400,000 400,000 
Unsecured 4.15% Senior Notes, due January 2043
500,000 500,000 
Unsecured 4.125% Senior Notes, due October 2044
750,000 750,000 
Unsecured 4.30% Senior Notes, due October 2048
600,000 600,000 
Unsecured 4.125% Senior Notes, due March 2049
450,000 450,000 
Unsecured 3.375% Senior Notes, due September 2049
500,000 500,000 
Unsecured 2.85% Senior Notes, due February 2052
600,000 600,000 
Unsecured 5.75% Senior Notes, due October 2052
500,000 500,000 
Unsecured 6.20% Senior Notes, due November 2053
500,000 500,000 
Unsecured 5.00% Senior Notes, due December 2054
650,000 — 
Medium-term note Series A, 1995-1, 6.67%, due December 2025
10,000 10,000 
Unsecured 6.75% Debentures, due July 2028
150,000 150,000 
Finance lease obligations48,486 48,890 
Total long-term debt8,483,486 7,833,890 
Less:
Original issue premium on unsecured senior notes and debentures(4,135)(9,071)
Debt issuance cost62,566 57,664 
Current maturities of long-term debt11,681 1,651 
Total long-term debt, net$8,413,374 $7,783,646 
On October 1, 2024, we completed a public offering of $650 million of 5.00% senior notes due December 2054, with an effective interest rate of 3.90%, after giving effect to the offering costs and settlement of our interest rate swaps. The net proceeds from the offering, after the underwriting discount and offering expenses, of $639.4 million were used for general corporate purposes.
Short-term debt
We utilize short-term debt to provide cost-effective, short-term financing until it can be replaced with a balance of long-term debt and equity financing that achieves the Company’s desired capital structure. Our short-term borrowing requirements are driven primarily by construction work in progress and the seasonal nature of the natural gas business.
Our short-term borrowing requirements are satisfied through a combination of a $1.5 billion commercial paper program and four committed revolving credit facilities with third-party lenders that provide $3.1 billion of total working capital funding.
Our commercial paper program is supported by a five-year unsecured $1.5 billion credit facility that expires on March 28, 2029. This facility bears interest at a base rate or at a Term SOFR-based rate for the applicable interest period, plus a margin ranging from zero percent to 0.25 percent for base rate advances or a margin ranging from 0.75 percent to 1.25 percent for Term SOFR-based advances, based on the Company’s credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the total committed loan to $1.75 billion. At December 31, 2024 and September 30, 2024, there were no amounts outstanding under our commercial paper program.
We also have a $1.5 billion three-year unsecured revolving credit facility, which expires March 28, 2027 and is used to provide additional working capital funding. This facility bears interest at a base rate or at a Term SOFR-based rate for the applicable interest period, plus a margin ranging from zero percent to 0.25 percent for base rate advances or a margin ranging from 0.75 percent to 1.25 percent for Term SOFR-based advances, based on the Company's credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the total committed loan to $1.75 billion. At December 31, 2024 and September 30, 2024, there were no borrowings outstanding under this facility.
Additionally, we have a $50 million 364-day unsecured facility, which will expire March 31, 2025 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of December 31, 2024 and September 30, 2024.
Finally, we have a $50 million 364-day unsecured revolving credit facility, which will expire March 31, 2025 and is used to issue letters of credit and to provide working capital funding. At December 31, 2024, there were no borrowings outstanding under this facility; however, outstanding letters of credit reduced the total amount available to us to $44.4 million.
Debt covenants
The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total-debt-to-total-capitalization of no greater than 70 percent. At December 31, 2024, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 41 percent. In addition, both the interest margin and the fee that we pay on unused amounts under certain of these facilities are subject to adjustment depending upon our credit ratings.
These credit facilities and our public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales, and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as certain of our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or if not paid at maturity. We were in compliance with all of our debt covenants as of December 31, 2024. If we were unable to comply with our debt covenants, we would likely be required to repay our outstanding balances on demand, provide additional collateral or take other corrective actions.
v3.25.0.1
Shareholders' Equity
 3 Months Ended
Dec. 31, 2024
Equity [Abstract]  
Shareholders' Equity Shareholders' Equity
The following tables present a reconciliation of changes in stockholders' equity for the three months ended December 31, 2024 and 2023.
 Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
 (In thousands, except share and per share data)
Balance, September 30, 2024
155,258,845 $776 $7,474,559 $465,715 $4,216,619 $12,157,669 
Net income— — — — 351,858 351,858 
Other comprehensive income— — — 16,423 — 16,423 
Cash dividends ($0.87 per share)
— — — — (135,453)(135,453)
Common stock issued:
Public and other stock offerings3,329,358 17 383,520 — — 383,537 
Stock-based compensation plans137,862 1 6,446 — — 6,447 
Balance, December 31, 2024158,726,065 $794 $7,864,525 $482,138 $4,433,024 $12,780,481 
 Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
 (In thousands, except share and per share data)
Balance, September 30, 2023
148,492,783 $742 $6,684,120 $518,528 $3,666,674 $10,870,064 
Net income— — — — 311,292 311,292 
Other comprehensive loss— — — (49,936)— (49,936)
Cash dividends ($0.805 per share)
— — — — (119,898)(119,898)
Common stock issued:
Public and other stock offerings2,177,864 11 257,757 — — 257,768 
Stock-based compensation plans163,750 1 3,918 — — 3,919 
Balance, December 31, 2023150,834,397 $754 $6,945,795 $468,592 $3,858,068 $11,273,209 
Shelf Registration, At-the-Market Equity Sales Program and Equity Issuances
On December 3, 2024, we filed a shelf registration statement with the Securities and Exchange Commission (SEC) that allows us to issue up to $8.0 billion in common stock and/or debt securities, which expires December 3, 2027. At December 31, 2024, $6.3 billion of securities were available for issuance under this shelf registration statement.
On December 3, 2024, we filed a prospectus supplement under the shelf registration statement relating to an at-the-market (ATM) equity sales program under which we may issue and sell shares of our common stock up to an aggregate offering price of $1.7 billion through December 3, 2027 (including shares of common stock that may be sold pursuant to forward sale agreements entered into concurrently with the ATM equity sales program). This ATM equity sales program replaced our previous ATM equity sales program, filed on May 8, 2024.
During the three months ended December 31, 2024, we executed forward sales under our ATM equity sales program with various forward sellers who borrowed and sold 3,397,596 shares of our common stock at an aggregate price of $476.0 million. During the three months ended December 31, 2024, we also settled forward sale agreements with respect to 3,300,904 shares that had been borrowed and sold by various forward sellers under the ATM program for net proceeds of $379.5 million. As of December 31, 2024, $1.2 billion of equity was available for issuance under our existing ATM program. Additionally, we had $1.5 billion in available proceeds from outstanding forward sale agreements, as detailed below.
MaturityShares AvailableNet Proceeds Available
(In thousands)		Forward Price
June 30, 2025630,514 $73,312 $116.27 
September 30, 2025815,655 96,179 $117.92 
December 31, 20252,344,567 297,079 $126.71 
March 31, 20263,627,033 462,383 $127.48 
June 30, 2026669,043 88,951 $132.95 
December 31, 20263,300,000 457,866 $138.75 
Total11,386,812 $1,475,770 $129.60 
Accumulated Other Comprehensive Income (Loss)
We record deferred gains (losses) in AOCI related to available-for-sale debt securities and interest rate agreement cash flow hedges. Deferred gains (losses) for our available-for-sale debt securities are recognized in earnings upon settlement, while deferred gains (losses) related to our interest rate agreement cash flow hedges are recognized in earnings on a straight-line basis over the life of the related financing. The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss).
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2024$213 $465,502 $465,715 
Other comprehensive income (loss) before reclassifications(138)19,719 19,581 
Amounts reclassified from accumulated other comprehensive income— (3,158)(3,158)
Net current-period other comprehensive income (loss)(138)16,561 16,423 
December 31, 2024$75 $482,063 $482,138 
 
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2023$(369)$518,897 $518,528 
Other comprehensive income (loss) before reclassifications296 (47,741)(47,445)
Amounts reclassified from accumulated other comprehensive income— (2,491)(2,491)
Net current-period other comprehensive income (loss)296 (50,232)(49,936)
December 31, 2023$(73)$468,665 $468,592 
v3.25.0.1
Securitization
 3 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Securitization Securitization
Kansas
Atmos Energy Kansas Securitization I, LLC (AEK), a special-purpose entity wholly owned by Atmos Energy, was formed for the purpose of issuing securitized bonds to recover extraordinary costs incurred during Winter Storm Uri in February 2021. In June 2023, AEK completed a public offering of $95 million of Securitized Utility Tariff Bonds. AEK's assets cannot be used to settle Atmos Energy's obligations, and the holders of the Securitized Utility Tariff Bonds have no recourse against Atmos Energy.
As described in Note 10 of our Annual Report on Form 10-K for the fiscal year ended September 30, 2024, AEK is considered to be a variable interest entity. As a result, AEK is included in the condensed consolidated financial statements of Atmos Energy.
The following table summarizes the impact of AEK on our condensed consolidated balance sheets, for the periods indicated:
December 31, 2024September 30, 2024
 (In thousands)
Restricted cash and cash equivalents$4,870 $1,516 
Other current assets$12 $3 
Securitized intangible asset, net$80,580 $82,844 
Accrued interest$1,462 $365 
Current maturities of securitized long-term debt$8,207 $8,207 
Securitized long-term debt$76,871 $76,871 
The following table summarizes the impact of AEK on our condensed consolidated statement of comprehensive income, for the period indicated:
Three Months Ended December 31, 2024Three Months Ended December 31, 2023
 
Operating revenues$3,393 $3,333 
Operation and maintenance expense(61)— 
Amortization expense(2,264)(2,166)
Interest expense, net(1,068)(1,167)
Income before income taxes$— $— 
The securitized long-term debt is recorded at carrying value. The fair value of the securitized long-term debt is determined using third party market value quotations, which are considered Level 2 fair value measurements for debt instruments where fair value is determined using the most recent available quoted market price. The carrying value and fair value of the securitized long-term debt as of December 31, 2024 is $85.1 million and $85.0 million.
Texas
In March 2023, the Texas Natural Gas Securitization Finance Corporation (the Finance Corporation), with the authority of the Texas Public Finance Authority (TPFA), issued $3.5 billion in customer rate relief bonds with varying scheduled final maturities from 12 to 18 years. The bonds are obligations of the Finance Corporation, payable from the customer rate relief charges and other bond collateral, and are not an obligation of Atmos Energy. We began collecting the customer rate relief charges on October 1, 2023, and any such property collected is solely owned by the Finance Corporation and not available to pay creditors of Atmos Energy.
v3.25.0.1
Interim Pension and Other Postretirement Benefit Plan Information
 3 Months Ended
Dec. 31, 2024
Retirement Benefits, Description [Abstract]  
Interim Pension and Other Postretirement Benefit Plan Information Interim Pension and Other Postretirement Benefit Plan Information
The components of our net periodic pension cost for our pension and other postretirement benefit plans for the three months ended December 31, 2024 and 2023 are presented in the following tables. Most of these costs are recoverable through our tariff rates. A portion of these costs is capitalized into our rate base or deferred as a regulatory asset or liability. The remaining costs are recorded as a component of operation and maintenance expense or other non-operating expense.
 Three Months Ended December 31
 Pension BenefitsOther Benefits
 2024202320242023
 (In thousands)
Components of net periodic pension cost:
Service cost$2,837 $2,389 $2,033 $1,507 
Interest cost (1)
6,663 7,497 3,365 3,509 
Expected return on assets (1)
(7,655)(7,202)(3,831)(3,128)
Amortization of prior service cost (credit) (1)
— — (3,260)(3,260)
Amortization of actuarial (gain) loss (1)
256 118 (2,429)(2,718)
Settlements (1)
— 776 — — 
Net periodic pension cost$2,101 $3,578 $(4,122)$(4,090)
(1)    The components of net periodic cost other than the service cost component are included in the line item other non-operating expense in the condensed consolidated statements of comprehensive income or are capitalized on the condensed consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024.
v3.25.0.1
Commitments and Contingencies
 3 Months Ended
Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies Commitments and Contingencies
Litigation and Environmental Matters
In the normal course of business, we are subject to various legal and regulatory proceedings. For such matters, we record liabilities when they are considered probable and estimable, based on currently available facts, our historical experience and our estimates of the ultimate outcome or resolution of the liability in the future. While the outcome of these proceedings is uncertain and a loss in excess of the amount we have accrued is possible though not reasonably estimable, it is the opinion of management that any amounts exceeding the accruals will not have a material adverse impact on our financial position, results of operations or cash flows.
The National Transportation Safety Board (NTSB) issued a Preliminary Report on February 14, 2024 relating to its investigation of two incidents that occurred in Jackson, Mississippi on January 24 and 27, 2024 that resulted in one fatality. Atmos Energy is working closely with the NTSB and other state and federal regulators to help determine causal factors.
The NTSB issued a Preliminary Report on December 30, 2024 relating to its investigation of an incident that occurred in Avondale, Louisiana on December 2, 2024 that resulted in one fatality. Atmos Energy is working closely with the NTSB and other state and federal regulators to help determine causal factors.
We are a party to various other litigation and environmental-related matters or claims that have arisen in the ordinary course of our business. While the results of such litigation and response actions to such environmental-related matters or claims cannot be predicted with certainty, we continue to believe the final outcome of such litigation and matters or claims will not have a material adverse effect on our financial condition, results of operations, or cash flows.
Purchase Commitments
Our distribution divisions maintain supply contracts with several vendors that generally cover a period of up to one year. Commitments for estimated base gas volumes are established under these contracts on a monthly basis at contractually negotiated prices. Commitments for incremental daily purchases are made as necessary during the month in accordance with the terms of the individual contract.
Our Mid-Tex Division also maintains a limited number of long-term supply contracts to ensure a reliable source of gas for our customers in its service area, which obligate it to purchase specified volumes at prices under contracts indexed to natural gas hubs or fixed price contracts. These purchase commitment contracts are detailed in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. At December 31, 2024, we were committed to purchase 55.5 Bcf within one year and 29.9 Bcf within two to three years under indexed contracts. At December 31, 2024, we were committed to purchase 3.9 Bcf within one year under fixed price contracts with a weighted average price of $3.26 per Mcf.
Rate Regulatory Proceedings
As of December 31, 2024, routine rate regulatory proceedings were in progress in several of our service areas, which are discussed in further detail below in Management’s Discussion and Analysis — Recent Ratemaking Developments. Except for these proceedings, there were no material changes to rate regulatory proceedings for the three months ended December 31, 2024.
v3.25.0.1
Income Taxes
 3 Months Ended
Dec. 31, 2024
Income Tax Disclosure [Abstract]  
Income Taxes Income Taxes
Income Tax Expense
Our interim effective tax rates reflect the estimated annual effective tax rates for the fiscal years ended September 30, 2025 and 2024, adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended December 31, 2024 and 2023 were 18.4% and 14.7%. These effective tax rates differ from the federal statutory tax rate of 21% primarily due to the amortization of excess deferred federal income tax liabilities, tax credits, state income taxes, and other permanent book-to-tax differences. These adjustments have a relative impact on the effective tax rate proportionally to pretax income or loss.
Regulatory Excess Deferred Taxes
Regulatory excess net deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of the Tax Cuts and Jobs Act of 2017 (the TCJA), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. Currently, the regulatory excess net deferred tax liability of $198.8 million is being returned over various periods. Of this amount, $135.3 million is being returned to customers over 12 - 60 months. An additional $49.0 million is being returned to customers on a provisional basis over 15 - 68 years until our regulators establish the final refund periods. The refund of the remaining $14.5 million will be addressed in future rate proceedings.
As of December 31, 2024 and September 30, 2024, $76.8 million and $79.7 million is recorded in other current liabilities.
v3.25.0.1
Financial Instruments
 3 Months Ended
Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Financial Instruments Financial Instruments
We currently use financial instruments to mitigate commodity price risk and interest rate risk. The objectives and strategies for using financial instruments and the related accounting for these financial instruments are fully described in Notes 2 and 16 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. During the three months ended December 31, 2024, there were no material changes in our objectives, strategies, and accounting for using financial instruments. Our financial instruments do not contain any credit-risk-related or other contingent
features that could cause payments to be accelerated when our financial instruments are in net liability positions. The following summarizes those objectives and strategies.
Commodity Risk Management Activities
Our purchased gas cost adjustment mechanisms essentially insulate our distribution segment from commodity price risk; however, our customers are exposed to the effects of volatile natural gas prices. We manage this exposure through a combination of physical storage, fixed-price forward contracts, and financial instruments, primarily over-the-counter swap and option contracts, in an effort to minimize the impact of natural gas price volatility on our customers during the winter heating season.
We typically seek to hedge between 25 and 50 percent of anticipated heating season gas purchases using financial instruments. For the 2024-2025 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we anticipate hedging approximately 24.0 Bcf of the winter flowing gas requirements. We have not designated these financial instruments as hedges for accounting purposes.
Interest Rate Risk Management Activities
We manage interest rate risk by periodically entering into financial instruments to effectively fix the Treasury yield component of the interest cost associated with anticipated financings.
The following table summarizes our existing forward starting interest rate swaps as of December 31, 2024. These swaps were designated as cash flow hedges at the time the agreements were executed.
Planned Debt Issuance DateAmount Hedged
(In thousands)
Fiscal 2026$300,000 
$300,000 
Quantitative Disclosures Related to Financial Instruments
The following tables present detailed information concerning the impact of financial instruments on our condensed consolidated balance sheet and statements of comprehensive income.
As of December 31, 2024, our financial instruments were comprised of both long and short commodity positions. A long position is a contract to purchase the commodity, while a short position is a contract to sell the commodity. As of December 31, 2024, we had 15,053 MMcf of net long commodity contracts outstanding. These contracts have not been designated as hedges.
Financial Instruments on the Balance Sheet
The following tables present the fair value and balance sheet classification of our financial instruments as of December 31, 2024 and September 30, 2024. The gross amounts of recognized assets and liabilities are netted within our condensed consolidated balance sheets to the extent that we have netting arrangements with our counterparties. However, as of December 31, 2024 and September 30, 2024, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
December 31, 2024
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsOther current assets /
Other current liabilities		$117,154 $— 
Total117,154 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		2,459 (4,063)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		1,338 — 
Total3,797 (4,063)
Gross / Net Financial Instruments$120,951 $(4,063)
 
September 30, 2024
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities		$91,981 $— 
Total91,981 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		2,091 (7,324)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		2,216 (313)
Total4,307 (7,637)
Gross / Net Financial Instruments$96,288 $(7,637)
Impact of Financial Instruments on the Statement of Comprehensive Income
Cash Flow Hedges
As discussed above, our distribution segment has interest rate agreements, which we designated as cash flow hedges at the time the agreements were executed. The net (gain) loss on settled interest rate agreements reclassified from AOCI into interest charges on our condensed consolidated statements of comprehensive income for the three months ended December 31, 2024 and 2023 was $(5.1) million and $(3.2) million.
The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three months ended December 31, 2024 and 2023.
 Three Months Ended December 31
 20242023
 (In thousands)
Increase (decrease) in fair value:
Interest rate agreements$19,719 $(47,741)
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements(3,158)(2,491)
Total other comprehensive income (loss) from hedging, net of tax$16,561 $(50,232)
Deferred gains (losses) recorded in AOCI associated with our interest rate agreements are recognized in earnings as they are amortized over the terms of the underlying debt instruments. As of December 31, 2024, we had $391.0 million of net realized gains in AOCI associated with our interest rate agreements. The following amounts, net of deferred taxes, represent the expected recognition in earnings of the deferred net gains recorded in AOCI associated with our interest rate agreements, based upon the fair values of these agreements at the date of settlement. The remaining amortization periods for these settled amounts extend through fiscal 2055. However, the table below does not include the expected recognition in earnings of our outstanding interest rate swaps as those instruments have not yet settled.
Interest Rate
Agreements
 (In thousands)
Next twelve months$15,925 
Thereafter375,062 
Total$390,987 

Financial Instruments Not Designated as Hedges
As discussed above, commodity contracts which are used in our distribution segment are not designated as hedges. However, there is no earnings impact on our distribution segment as a result of the use of these financial instruments because the gains and losses arising from the use of these financial instruments are recognized in the consolidated statement of comprehensive income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue. Accordingly, the impact of these financial instruments is excluded from this presentation.
v3.25.0.1
Fair Value Measurements
 3 Months Ended
Dec. 31, 2024
Fair Value Disclosures [Abstract]  
Fair Value Measurements Fair Value Measurements
We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, restricted cash and cash equivalents, accounts receivable, accounts payable, and short-term debt at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. During the three months ended December 31, 2024, there were no changes in these methods.
Fair value measurements also apply to the valuation of our pension and postretirement plan assets. Current accounting guidance requires employers to annually disclose information about fair value measurements of the assets of a defined benefit pension or other postretirement plan. The fair value of these assets is presented in Note 11 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024.
Quantitative Disclosures
Financial Instruments
The classification of our fair value measurements requires judgment regarding the degree to which market data is observable or corroborated by observable market data. Authoritative accounting literature establishes a fair value hierarchy that prioritizes the inputs used to measure fair value based on observable and unobservable data. The hierarchy categorizes the inputs into three levels, with the highest priority given to unadjusted quoted prices in active markets for identical assets and liabilities (Level 1), with the lowest priority given to unobservable inputs (Level 3). The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of December 31, 2024 and September 30, 2024. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement.
Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)		Netting and
Cash
Collateral		December 31, 2024
 (In thousands)
Assets:
Financial instruments$— $120,951 $— $— $120,951 
Debt and equity securities
Registered investment companies27,344 — — — 27,344 
Bond mutual funds40,332 — — — 40,332 
Bonds (2)
— 39,381 — — 39,381 
Money market funds— 2,507 — — 2,507 
Total debt and equity securities67,676 41,888 — — 109,564 
Total assets$67,676 $162,839 $— $— $230,515 
Liabilities:
Financial instruments$— $4,063 $— $— $4,063 

Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)		Netting and
Cash
Collateral		September 30, 2024
 (In thousands)
Assets:
Financial instruments$— $96,288 $— $— $96,288 
Debt and equity securities
Registered investment companies28,311 — — — 28,311 
Bond mutual funds40,341 — — — 40,341 
Bonds (2)
— 39,142 — — 39,142 
Money market funds— 2,800 — — 2,800 
Total debt and equity securities68,652 41,942 — — 110,594 
Total assets$68,652 $138,230 $— $— $206,882 
Liabilities:
Financial instruments$— $7,637 $— $— $7,637 
 
(1)Our Level 2 measurements consist of over-the-counter options and swaps, which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds, which are valued based on the most recent available quoted market prices and money market funds that are valued at cost.
(2)Our investments in bonds are considered available-for-sale debt securities in accordance with current accounting guidance.
Debt and equity securities are comprised of our available-for-sale debt securities and our equity securities. As described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024, we evaluate the performance of our available-for-sale debt securities on an investment by investment basis for impairment, taking into consideration the investment’s purpose, volatility, current returns, and any intent to sell the security. As of December 31, 2024, no allowance for credit losses was recorded for our available-for-sale debt securities. At December 31, 2024 and September 30, 2024, the amortized cost of our available-for-sale debt securities was $39.3 million and $38.9 million. At December 31, 2024, we maintained investments in bonds that have contractual maturity dates ranging from January 2025 through November 2027.
Other Fair Value Measures
Our long-term debt is recorded at carrying value. The fair value of our long-term debt, excluding finance leases, is determined using third party market value quotations, which are considered Level 1 fair value measurements for debt instruments with a recent, observable trade or Level 2 fair value measurements for debt instruments where fair value is
determined using the most recent available quoted market price. The carrying value of our finance leases materially approximates fair value. The following table presents the carrying value and fair value of our long-term debt, excluding finance leases, debt issuance costs and original issue premium or discount, as of December 31, 2024 and September 30, 2024:
 December 31, 2024September 30, 2024
 (In thousands)
Carrying Amount$8,435,000 $7,785,000 
Fair Value$7,484,877 $7,337,936 
v3.25.0.1
Concentration of Credit Risk
 3 Months Ended
Dec. 31, 2024
Risks and Uncertainties [Abstract]  
Concentration of Credit Risk Concentration of Credit Risk
Information regarding our concentration of credit risk is disclosed in Note 18 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. During the three months ended December 31, 2024, there were no material changes in our concentration of credit risk.
v3.25.0.1
Pay vs Performance Disclosure - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Pay vs Performance Disclosure    
Net income $ 351,858 $ 311,292
v3.25.0.1
Insider Trading Arrangements
 3 Months Ended
Dec. 31, 2024
Trading Arrangements, by Individual  
Rule 10b5-1 Arrangement Adopted false
Non-Rule 10b5-1 Arrangement Adopted false
Rule 10b5-1 Arrangement Terminated false
Non-Rule 10b5-1 Arrangement Terminated false
v3.25.0.1
Summary of Significant Accounting Policies (Policies)
 3 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]  
Recently issued accounting pronouncements
In November 2023, the Financial Accounting Standards Board (FASB) issued guidance which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. The amendment is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted, and the amendments should be applied retrospectively. This amendment will be effective for our Form 10-K for fiscal 2025 and our Form 10-Q for the first quarter of fiscal 2026. We are currently evaluating the impact this may have on our financial statement disclosures.
In December 2023, the FASB issued guidance which provides qualitative and quantitative updates to the rate reconciliation and income taxes paid disclosures, among others, in order to enhance the transparency of income tax disclosures, including consistent categories and greater disaggregation of information in the rate reconciliation and disaggregation by jurisdiction of income taxes paid. The amendment is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The amendments should be applied prospectively; however, retrospective application is also permitted. This amendment will be effective for our Form 10-K for fiscal 2026. We are currently evaluating the impact this amendment may have on our financial statement disclosures.
In November 2024, the FASB issued guidance that will require more detailed information about the types of expenses in commonly presented expense captions. The amendment is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. This amendment will be effective for our Form 10-K for fiscal 2028 and our Form 10-Q for the first quarter of fiscal 2029. We are currently evaluating the impact this may have on our financial statement disclosures.
Earnings per share We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock.
Fair value measurement
We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, restricted cash and cash equivalents, accounts receivable, accounts payable, and short-term debt at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024. During the three months ended December 31, 2024, there were no changes in these methods.
v3.25.0.1
Regulation (Tables)
 3 Months Ended
Dec. 31, 2024
Regulated Operations [Abstract]  
Schedule of Regulatory Assets
Regulatory assets and liabilities as of December 31, 2024 and September 30, 2024 included the following:
December 31,
2024		September 30,
2024
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$7,885 $11,243 
Infrastructure mechanisms (1)
189,939 246,734 
Winter Storm Uri incremental costs8,834 10,373 
Deferred gas costs169,203 159,762 
Regulatory excess deferred taxes (2)
50,941 51,380 
Recoverable loss on reacquired debt3,028 3,070 
Deferred pipeline record collection costs41,245 41,742 
APT annual System Safety and Integrity Rider (3)
35,290 38,632 
Other16,151 16,454 
$522,516 $579,390 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$249,790 $257,001 
Regulatory cost of removal obligation615,371 607,032 
Deferred gas costs3,731 9,142 
APT annual adjustment mechanism76,418 73,119 
Pension and postretirement benefit costs241,816 247,250 
Other36,282 34,338 
$1,223,408 $1,227,882 
 
(1)Infrastructure mechanisms in Texas, Louisiana, and Tennessee allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recoverable through base rates.
(2)Regulatory excess deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of Tax Cuts and Jobs Act of 2017 (the "TCJA"), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. See Note 12 to the condensed consolidated financial statements for further information.
(3)In APT's general rate case settlement in December 2023, the RRC approved a new annual compliance filing that allows APT to recover certain system safety and integrity costs incurred each year. Costs above a specified benchmark are deferred onto the balance sheet as incurred. Once the filing is approved by the RRC, the revenue and expense are recognized over 12 months resulting in no impact to operating income.
Schedule of Regulatory Liabilities
Regulatory assets and liabilities as of December 31, 2024 and September 30, 2024 included the following:
December 31,
2024		September 30,
2024
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$7,885 $11,243 
Infrastructure mechanisms (1)
189,939 246,734 
Winter Storm Uri incremental costs8,834 10,373 
Deferred gas costs169,203 159,762 
Regulatory excess deferred taxes (2)
50,941 51,380 
Recoverable loss on reacquired debt3,028 3,070 
Deferred pipeline record collection costs41,245 41,742 
APT annual System Safety and Integrity Rider (3)
35,290 38,632 
Other16,151 16,454 
$522,516 $579,390 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$249,790 $257,001 
Regulatory cost of removal obligation615,371 607,032 
Deferred gas costs3,731 9,142 
APT annual adjustment mechanism76,418 73,119 
Pension and postretirement benefit costs241,816 247,250 
Other36,282 34,338 
$1,223,408 $1,227,882 
 
(1)Infrastructure mechanisms in Texas, Louisiana, and Tennessee allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recoverable through base rates.
(2)Regulatory excess deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of Tax Cuts and Jobs Act of 2017 (the "TCJA"), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. See Note 12 to the condensed consolidated financial statements for further information.
(3)In APT's general rate case settlement in December 2023, the RRC approved a new annual compliance filing that allows APT to recover certain system safety and integrity costs incurred each year. Costs above a specified benchmark are deferred onto the balance sheet as incurred. Once the filing is approved by the RRC, the revenue and expense are recognized over 12 months resulting in no impact to operating income.
v3.25.0.1
Segment Information (Tables)
 3 Months Ended
Dec. 31, 2024
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment
Income statements and capital expenditures for the three months ended December 31, 2024 and 2023 by segment are presented in the following tables:
 Three Months Ended December 31, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$1,108,569 $67,430 $— $1,175,999 
Intersegment revenues766 187,960 (188,726)— 
Total operating revenues1,109,335 255,390 (188,726)1,175,999 
Purchased gas cost
422,570 (58)(188,464)234,048 
Operation and maintenance expense154,514 52,792 (262)207,044 
Depreciation and amortization expense133,627 46,906 — 180,533 
Taxes, other than income82,576 12,318 — 94,894 
Operating income316,048 143,432 — 459,480 
Other non-operating income10,084 14,550 — 24,634 
Interest charges34,249 18,676 — 52,925 
Income before income taxes
291,883 139,306 — 431,189 
Income tax expense51,670 27,661 — 79,331 
Net income$240,213 $111,645 $— $351,858 
Capital expenditures$625,649 $265,542 $— $891,191 
 Three Months Ended December 31, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$1,104,619 $53,848 $— $1,158,467 
Intersegment revenues719 157,321 (158,040)— 
Total operating revenues1,105,338 211,169 (158,040)1,158,467 
Purchased gas cost
496,662 4 (157,797)338,869 
Operation and maintenance expense127,615 38,973 (243)166,345 
Depreciation and amortization expense119,685 44,923 — 164,608 
Taxes, other than income80,895 8,645 — 89,540 
Operating income280,481 118,624 — 399,105 
Other non-operating income5,839 12,047 — 17,886 
Interest charges34,581 17,294 — 51,875 
Income before income taxes
251,739 113,377 — 365,116 
Income tax expense30,302 23,522 — 53,824 
Net income$221,437 $89,855 $— $311,292 
Capital expenditures$539,158 $230,492 $— $769,650 

Balance sheet information at December 31, 2024 and September 30, 2024 by segment is presented in the following tables:
 December 31, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$16,942,174 $6,019,869 $— $22,962,043 
Total assets$25,623,410 $6,341,439 $(5,467,756)$26,497,093 
 September 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$16,372,659 $5,831,708 $— $22,204,367 
Total assets$24,328,877 $6,181,558 $(5,315,970)$25,194,465 
v3.25.0.1
Earnings Per Share (Tables)
 3 Months Ended
Dec. 31, 2024
Earnings Per Share [Abstract]  
Schedule of Earnings Per Share, Basic and Diluted
Basic and diluted earnings per share for the three months ended December 31, 2024 and 2023 are calculated as follows:
 Three Months Ended December 31
 20242023
 (In thousands, except per share amounts)
Basic Earnings Per Share
Net income$351,858 $311,292 
Less: Income allocated to participating securities
159 186 
Income available to common shareholders
$351,699 $311,106 
Basic weighted average shares outstanding
156,301 149,796 
Net income per share — Basic
$2.25 $2.08 
Diluted Earnings Per Share
Income available to common shareholders$351,699 $311,106 
Effect of dilutive shares
— — 
Income available to common shareholders
$351,699 $311,106 
Basic weighted average shares outstanding
156,301 149,796 
Dilutive shares1,523 — 
Diluted weighted average shares outstanding
157,824 149,796 
Net income per share — Diluted$2.23 $2.08 
v3.25.0.1
Revenue and Accounts Receivable (Tables)
 3 Months Ended
Dec. 31, 2024
Revenue from Contract with Customer [Abstract]  
Schedule of Disaggregation of Revenue The following tables disaggregate our revenue from contracts with customers by customer type and segment and provide a reconciliation to total operating revenues, including intersegment revenues, for the three months ended December 31, 2024 and 2023.
Three Months Ended December 31, 2024Three Months Ended December 31, 2023
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$693,050 $— $727,682 $— 
Commercial266,054 — 277,253 — 
Industrial26,321 — 28,231 — 
Public authority and other12,881 — 14,584 — 
Total gas sales revenues998,306 — 1,047,750 — 
Transportation revenues36,727 266,029 33,767 215,305 
Miscellaneous revenues3,022 2,664 2,643 3,042 
Revenues from contracts with customers1,038,055 268,693 1,084,160 218,347 
Alternative revenue program revenues67,336 (13,303)17,401 (7,178)
Other revenues3,944 — 3,777 — 
Total operating revenues$1,109,335 $255,390 $1,105,338 $211,169 
Schedule of Allowance for Credit Loss Activity Rollforwards of our allowance for uncollectible accounts for the three months ended December 31, 2024 and 2023 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 89 percent of our customers as we have the ability to collect these gas costs through our gas cost recovery mechanisms in most of our jurisdictions.
In December 2023, the Mississippi Public Service Commission approved the recovery of uncollectible accounts through our purchased gas cost mechanism over a two-year period rather than through our annual filing mechanism over a one-year period. As a result of this decision, we recorded a $13.9 million reduction to bad debt expense during the first quarter of fiscal 2024. Of this amount, $9.7 million represents future recovery of customer receivables previously written off since April 2022 but not yet recovered through our rates. This amount increased our deferred gas cost regulatory asset. The remaining $4.2 million reduction represents a reversal of our allowance for uncollectible accounts for customer balances that have not yet been written off.
 Three Months Ended December 31, 2024
 (In thousands)
Beginning balance, September 30, 2024$37,056 
Current period provisions8,623 
Write-offs charged against allowance(7,447)
Recoveries of amounts previously written off934 
Ending balance, December 31, 2024
$39,166 
 Three Months Ended December 31, 2023
 (In thousands)
Beginning balance, September 30, 2023$40,840 
Current period provisions6,750 
Write-offs charged against allowance(8,757)
Recoveries of amounts previously written off765 
Mississippi recovery of uncollectible accounts(4,192)
Ending balance, December 31, 2023
$35,406 
v3.25.0.1
Debt (Tables)
 3 Months Ended
Dec. 31, 2024
Debt Disclosure [Abstract]  
Schedule of Long-term Debt Instruments
Long-term debt at December 31, 2024 and September 30, 2024 consisted of the following:
December 31, 2024September 30, 2024
 (In thousands)
Unsecured 3.00% Senior Notes, due June 2027
$500,000 $500,000 
Unsecured 2.625% Senior Notes, due September 2029
500,000 500,000 
Unsecured 1.50% Senior Notes, due January 2031
600,000 600,000 
Unsecured 5.45% Senior Notes, due October 2032
300,000 300,000 
Unsecured 5.90% Senior Notes, due November 2033

725,000 725,000 
Unsecured 5.95% Senior Notes, due October 2034
200,000 200,000 
Unsecured 5.50% Senior Notes, due June 2041
400,000 400,000 
Unsecured 4.15% Senior Notes, due January 2043
500,000 500,000 
Unsecured 4.125% Senior Notes, due October 2044
750,000 750,000 
Unsecured 4.30% Senior Notes, due October 2048
600,000 600,000 
Unsecured 4.125% Senior Notes, due March 2049
450,000 450,000 
Unsecured 3.375% Senior Notes, due September 2049
500,000 500,000 
Unsecured 2.85% Senior Notes, due February 2052
600,000 600,000 
Unsecured 5.75% Senior Notes, due October 2052
500,000 500,000 
Unsecured 6.20% Senior Notes, due November 2053
500,000 500,000 
Unsecured 5.00% Senior Notes, due December 2054
650,000 — 
Medium-term note Series A, 1995-1, 6.67%, due December 2025
10,000 10,000 
Unsecured 6.75% Debentures, due July 2028
150,000 150,000 
Finance lease obligations48,486 48,890 
Total long-term debt8,483,486 7,833,890 
Less:
Original issue premium on unsecured senior notes and debentures(4,135)(9,071)
Debt issuance cost62,566 57,664 
Current maturities of long-term debt11,681 1,651 
Total long-term debt, net$8,413,374 $7,783,646 
v3.25.0.1
Shareholders' Equity (Tables)
 3 Months Ended
Dec. 31, 2024
Equity [Abstract]  
Schedule of Reconciliation of Changes in Stockholders Equity
The following tables present a reconciliation of changes in stockholders' equity for the three months ended December 31, 2024 and 2023.
 Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
 (In thousands, except share and per share data)
Balance, September 30, 2024
155,258,845 $776 $7,474,559 $465,715 $4,216,619 $12,157,669 
Net income— — — — 351,858 351,858 
Other comprehensive income— — — 16,423 — 16,423 
Cash dividends ($0.87 per share)
— — — — (135,453)(135,453)
Common stock issued:
Public and other stock offerings3,329,358 17 383,520 — — 383,537 
Stock-based compensation plans137,862 1 6,446 — — 6,447 
Balance, December 31, 2024158,726,065 $794 $7,864,525 $482,138 $4,433,024 $12,780,481 
 Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
 (In thousands, except share and per share data)
Balance, September 30, 2023
148,492,783 $742 $6,684,120 $518,528 $3,666,674 $10,870,064 
Net income— — — — 311,292 311,292 
Other comprehensive loss— — — (49,936)— (49,936)
Cash dividends ($0.805 per share)
— — — — (119,898)(119,898)
Common stock issued:
Public and other stock offerings2,177,864 11 257,757 — — 257,768 
Stock-based compensation plans163,750 1 3,918 — — 3,919 
Balance, December 31, 2023150,834,397 $754 $6,945,795 $468,592 $3,858,068 $11,273,209 
Schedule of Forward Sales Agreements Additionally, we had $1.5 billion in available proceeds from outstanding forward sale agreements, as detailed below.
MaturityShares AvailableNet Proceeds Available
(In thousands)		Forward Price
June 30, 2025630,514 $73,312 $116.27 
September 30, 2025815,655 96,179 $117.92 
December 31, 20252,344,567 297,079 $126.71 
March 31, 20263,627,033 462,383 $127.48 
June 30, 2026669,043 88,951 $132.95 
December 31, 20263,300,000 457,866 $138.75 
Total11,386,812 $1,475,770 $129.60 
Schedule of Accumulated Other Comprehensive Income (Loss) The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss).
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2024$213 $465,502 $465,715 
Other comprehensive income (loss) before reclassifications(138)19,719 19,581 
Amounts reclassified from accumulated other comprehensive income— (3,158)(3,158)
Net current-period other comprehensive income (loss)(138)16,561 16,423 
December 31, 2024$75 $482,063 $482,138 
 
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2023$(369)$518,897 $518,528 
Other comprehensive income (loss) before reclassifications296 (47,741)(47,445)
Amounts reclassified from accumulated other comprehensive income— (2,491)(2,491)
Net current-period other comprehensive income (loss)296 (50,232)(49,936)
December 31, 2023$(73)$468,665 $468,592 
v3.25.0.1
Securitization (Tables)
 3 Months Ended
Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Condensed Consolidated Balance Sheet
The following table summarizes the impact of AEK on our condensed consolidated balance sheets, for the periods indicated:
December 31, 2024September 30, 2024
 (In thousands)
Restricted cash and cash equivalents$4,870 $1,516 
Other current assets$12 $3 
Securitized intangible asset, net$80,580 $82,844 
Accrued interest$1,462 $365 
Current maturities of securitized long-term debt$8,207 $8,207 
Securitized long-term debt$76,871 $76,871 
Schedule of Condensed Consolidated Statement of Comprehensive Income
The following table summarizes the impact of AEK on our condensed consolidated statement of comprehensive income, for the period indicated:
Three Months Ended December 31, 2024Three Months Ended December 31, 2023
 
Operating revenues$3,393 $3,333 
Operation and maintenance expense(61)— 
Amortization expense(2,264)(2,166)
Interest expense, net(1,068)(1,167)
Income before income taxes$— $— 
v3.25.0.1
Interim Pension and Other Postretirement Benefit Plan Information (Tables)
 3 Months Ended
Dec. 31, 2024
Retirement Benefits, Description [Abstract]  
Schedule of Net Benefit Costs
 Three Months Ended December 31
 Pension BenefitsOther Benefits
 2024202320242023
 (In thousands)
Components of net periodic pension cost:
Service cost$2,837 $2,389 $2,033 $1,507 
Interest cost (1)
6,663 7,497 3,365 3,509 
Expected return on assets (1)
(7,655)(7,202)(3,831)(3,128)
Amortization of prior service cost (credit) (1)
— — (3,260)(3,260)
Amortization of actuarial (gain) loss (1)
256 118 (2,429)(2,718)
Settlements (1)
— 776 — — 
Net periodic pension cost$2,101 $3,578 $(4,122)$(4,090)
(1)    The components of net periodic cost other than the service cost component are included in the line item other non-operating expense in the condensed consolidated statements of comprehensive income or are capitalized on the condensed consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2024.
v3.25.0.1
Financial Instruments (Tables)
 3 Months Ended
Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Schedule of Interest Rate Derivatives
The following table summarizes our existing forward starting interest rate swaps as of December 31, 2024. These swaps were designated as cash flow hedges at the time the agreements were executed.
Planned Debt Issuance DateAmount Hedged
(In thousands)
Fiscal 2026$300,000 
$300,000 
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value
The following tables present the fair value and balance sheet classification of our financial instruments as of December 31, 2024 and September 30, 2024. The gross amounts of recognized assets and liabilities are netted within our condensed consolidated balance sheets to the extent that we have netting arrangements with our counterparties. However, as of December 31, 2024 and September 30, 2024, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
December 31, 2024
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsOther current assets /
Other current liabilities		$117,154 $— 
Total117,154 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		2,459 (4,063)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		1,338 — 
Total3,797 (4,063)
Gross / Net Financial Instruments$120,951 $(4,063)
 
September 30, 2024
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities		$91,981 $— 
Total91,981 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		2,091 (7,324)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		2,216 (313)
Total4,307 (7,637)
Gross / Net Financial Instruments$96,288 $(7,637)
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)
The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three months ended December 31, 2024 and 2023.
 Three Months Ended December 31
 20242023
 (In thousands)
Increase (decrease) in fair value:
Interest rate agreements$19,719 $(47,741)
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements(3,158)(2,491)
Total other comprehensive income (loss) from hedging, net of tax$16,561 $(50,232)
Schedule of Expected Deferred Gains (Losses) Recognition The following amounts, net of deferred taxes, represent the expected recognition in earnings of the deferred net gains recorded in AOCI associated with our interest rate agreements, based upon the fair values of these agreements at the date of settlement. The remaining amortization periods for these settled amounts extend through fiscal 2055. However, the table below does not include the expected recognition in earnings of our outstanding interest rate swaps as those instruments have not yet settled.
Interest Rate
Agreements
 (In thousands)
Next twelve months$15,925 
Thereafter375,062 
Total$390,987 
v3.25.0.1
Fair Value Measurements (Tables)
 3 Months Ended
Dec. 31, 2024
Fair Value Disclosures [Abstract]  
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of December 31, 2024 and September 30, 2024. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement.
Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)		Netting and
Cash
Collateral		December 31, 2024
 (In thousands)
Assets:
Financial instruments$— $120,951 $— $— $120,951 
Debt and equity securities
Registered investment companies27,344 — — — 27,344 
Bond mutual funds40,332 — — — 40,332 
Bonds (2)
— 39,381 — — 39,381 
Money market funds— 2,507 — — 2,507 
Total debt and equity securities67,676 41,888 — — 109,564 
Total assets$67,676 $162,839 $— $— $230,515 
Liabilities:
Financial instruments$— $4,063 $— $— $4,063 

Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)		Netting and
Cash
Collateral		September 30, 2024
 (In thousands)
Assets:
Financial instruments$— $96,288 $— $— $96,288 
Debt and equity securities
Registered investment companies28,311 — — — 28,311 
Bond mutual funds40,341 — — — 40,341 
Bonds (2)
— 39,142 — — 39,142 
Money market funds— 2,800 — — 2,800 
Total debt and equity securities68,652 41,942 — — 110,594 
Total assets$68,652 $138,230 $— $— $206,882 
Liabilities:
Financial instruments$— $7,637 $— $— $7,637 
 
(1)Our Level 2 measurements consist of over-the-counter options and swaps, which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds, which are valued based on the most recent available quoted market prices and money market funds that are valued at cost.
(2)Our investments in bonds are considered available-for-sale debt securities in accordance with current accounting guidance.
Schedule of Carrying Values and Estimated Fair Values of Long-term Debt The following table presents the carrying value and fair value of our long-term debt, excluding finance leases, debt issuance costs and original issue premium or discount, as of December 31, 2024 and September 30, 2024:
 December 31, 2024September 30, 2024
 (In thousands)
Carrying Amount$8,435,000 $7,785,000 
Fair Value$7,484,877 $7,337,936 
v3.25.0.1
Nature of Business (Details)
customer in Millions
Dec. 31, 2024
regulatedDistributionDivision
state
customer
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Number of customers serviced (over) | customer 3.3
Number of regulated distribution divisions | regulatedDistributionDivision 6
Number of states with service areas | state 8
v3.25.0.1
Regulation - Schedule of Regulatory Assets and Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
Regulatory Asset [Line Items]    
Regulatory assets $ 522,516 $ 579,390
Regulatory Liabilities [Line Items]    
Regulatory liabilities 1,223,408 1,227,882
Regulatory excess deferred taxes    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 249,790 257,001
Regulatory cost of removal obligation    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 615,371 607,032
Deferred gas costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 3,731 9,142
APT annual adjustment mechanism    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 76,418 73,119
Pension and postretirement benefit costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 241,816 247,250
Other    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 36,282 34,338
Pension and postretirement benefit costs    
Regulatory Asset [Line Items]    
Regulatory assets 7,885 11,243
Infrastructure mechanisms    
Regulatory Asset [Line Items]    
Regulatory assets 189,939 246,734
Winter Storm Uri incremental costs    
Regulatory Asset [Line Items]    
Regulatory assets 8,834 10,373
Deferred gas costs    
Regulatory Asset [Line Items]    
Regulatory assets 169,203 159,762
Regulatory excess deferred taxes    
Regulatory Asset [Line Items]    
Regulatory assets 50,941 51,380
Recoverable loss on reacquired debt    
Regulatory Asset [Line Items]    
Regulatory assets 3,028 3,070
Deferred pipeline record collection costs    
Regulatory Asset [Line Items]    
Regulatory assets 41,245 41,742
APT annual System Safety and Integrity Rider    
Regulatory Asset [Line Items]    
Regulatory assets $ 35,290 38,632
Regulatory asset, recognition period 12 months  
Other    
Regulatory Asset [Line Items]    
Regulatory assets $ 16,151 $ 16,454
v3.25.0.1
Regulation - Narrative (Details) - Texas - Winter Storm Uri incremental costs - Winter Storm Uri - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended 28 Months Ended
Dec. 31, 2024
Sep. 30, 2024
Dec. 31, 2024
Regulatory Asset [Line Items]      
Regulatory asset, deferred costs     $ 32.4
Regulatory asset, recovered cost $ 1.6 $ 22.0  
Regulatory asset, deferred costs, remaining 8.8   8.8
Other current assets      
Regulatory Asset [Line Items]      
Regulatory asset, deferred costs, remaining 2.4   2.4
Deferred charges and other assets      
Regulatory Asset [Line Items]      
Regulatory asset, deferred costs, remaining $ 6.4   $ 6.4
v3.25.0.1
Segment Information - Narrative (Details)
Dec. 31, 2024
state
Segment Reporting [Abstract]  
Number of states with service areas 8
v3.25.0.1
Segment Information - Schedule of Income Statements and Capital Expenditures By Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Segment Reporting Information [Line Items]    
Operating revenues $ 1,175,999 $ 1,158,467
Purchased gas cost 234,048 338,869
Operation and maintenance expense 207,044 166,345
Depreciation and amortization expense 180,533 164,608
Taxes, other than income 94,894 89,540
Operating income 459,480 399,105
Other non-operating income (expense) 24,634 17,886
Interest charges 52,925 51,875
Income before income taxes 431,189 365,116
Income tax expense 79,331 53,824
Net income 351,858 311,292
Capital expenditures 891,191 769,650
Distribution    
Segment Reporting Information [Line Items]    
Operating revenues 1,108,569 1,104,619
Pipeline and Storage    
Segment Reporting Information [Line Items]    
Operating revenues 67,430 53,848
Eliminations    
Segment Reporting Information [Line Items]    
Operating revenues (188,726) (158,040)
Purchased gas cost (188,464) (157,797)
Operation and maintenance expense (262) (243)
Depreciation and amortization expense 0 0
Taxes, other than income 0 0
Operating income 0 0
Other non-operating income (expense) 0 0
Interest charges 0 0
Income before income taxes 0 0
Income tax expense 0 0
Net income 0 0
Capital expenditures 0 0
Eliminations | Distribution    
Segment Reporting Information [Line Items]    
Operating revenues (766) (719)
Eliminations | Pipeline and Storage    
Segment Reporting Information [Line Items]    
Operating revenues (187,960) (157,321)
Operating Segments | Distribution    
Segment Reporting Information [Line Items]    
Operating revenues 1,109,335 1,105,338
Purchased gas cost 422,570 496,662
Operation and maintenance expense 154,514 127,615
Depreciation and amortization expense 133,627 119,685
Taxes, other than income 82,576 80,895
Operating income 316,048 280,481
Other non-operating income (expense) 10,084 5,839
Interest charges 34,249 34,581
Income before income taxes 291,883 251,739
Income tax expense 51,670 30,302
Net income 240,213 221,437
Capital expenditures 625,649 539,158
Operating Segments | Pipeline and Storage    
Segment Reporting Information [Line Items]    
Operating revenues 255,390 211,169
Purchased gas cost (58) 4
Operation and maintenance expense 52,792 38,973
Depreciation and amortization expense 46,906 44,923
Taxes, other than income 12,318 8,645
Operating income 143,432 118,624
Other non-operating income (expense) 14,550 12,047
Interest charges 18,676 17,294
Income before income taxes 139,306 113,377
Income tax expense 27,661 23,522
Net income 111,645 89,855
Capital expenditures $ 265,542 $ 230,492
v3.25.0.1
Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
Segment Reporting Information [Line Items]    
Net property, plant and equipment $ 22,962,043 $ 22,204,367
Total assets 26,497,093 25,194,465
Operating Segments | Distribution    
Segment Reporting Information [Line Items]    
Net property, plant and equipment 16,942,174 16,372,659
Total assets 25,623,410 24,328,877
Operating Segments | Pipeline and Storage    
Segment Reporting Information [Line Items]    
Net property, plant and equipment 6,019,869 5,831,708
Total assets 6,341,439 6,181,558
Eliminations    
Segment Reporting Information [Line Items]    
Net property, plant and equipment 0 0
Total assets $ (5,467,756) $ (5,315,970)
v3.25.0.1
Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Basic Earnings Per Share    
Net income $ 351,858 $ 311,292
Less: Income allocated to participating securities 159 186
Income available to common shareholders $ 351,699 $ 311,106
Basic weighted average shares outstanding (in shares) 156,301 149,796
Net income per share - Basic (USD per share) $ 2.25 $ 2.08
Diluted Earnings Per Share    
Income available to common shareholders $ 351,699 $ 311,106
Effect of dilutive shares 0 0
Income available to common shareholders $ 351,699 $ 311,106
Basic weighted average shares outstanding (in shares) 156,301 149,796
Dilutive shares (in shares) 1,523 0
Diluted weighted average shares outstanding (in shares) 157,824 149,796
Net income per share - Diluted (USD per share) $ 2.23 $ 2.08
v3.25.0.1
Revenue and Accounts Receivable - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Disaggregation of Revenue [Line Items]    
Total operating revenues $ 1,175,999 $ 1,158,467
Distribution    
Disaggregation of Revenue [Line Items]    
Total operating revenues 1,108,569 1,104,619
Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Total operating revenues 67,430 53,848
Operating Segments | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 1,038,055 1,084,160
Alternative revenue program revenues 67,336 17,401
Other revenues 3,944 3,777
Total operating revenues 1,109,335 1,105,338
Operating Segments | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 268,693 218,347
Alternative revenue program revenues (13,303) (7,178)
Other revenues 0 0
Total operating revenues 255,390 211,169
Operating Segments | Gas sales revenues | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 998,306 1,047,750
Operating Segments | Gas sales revenues | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 0 0
Operating Segments | Transportation revenues | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 36,727 33,767
Operating Segments | Transportation revenues | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 266,029 215,305
Operating Segments | Miscellaneous revenues | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 3,022 2,643
Operating Segments | Miscellaneous revenues | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 2,664 3,042
Operating Segments | Residential | Gas sales revenues | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 693,050 727,682
Operating Segments | Residential | Gas sales revenues | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 0 0
Operating Segments | Commercial | Gas sales revenues | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 266,054 277,253
Operating Segments | Commercial | Gas sales revenues | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 0 0
Operating Segments | Industrial | Gas sales revenues | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 26,321 28,231
Operating Segments | Industrial | Gas sales revenues | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 0 0
Operating Segments | Public authority and other | Gas sales revenues | Distribution    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers 12,881 14,584
Operating Segments | Public authority and other | Gas sales revenues | Pipeline and Storage    
Disaggregation of Revenue [Line Items]    
Revenues from contracts with customers $ 0 $ 0
v3.25.0.1
Revenue and Accounts Receivable - Narrative (Details) - USD ($)
$ in Thousands
 3 Months Ended 33 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2024
Nov. 30, 2023
Disaggregation of Revenue [Line Items]        
Percent of customers excluded 89.00%      
Reduction to bad debt expense $ (8,623) $ (6,750)    
Recovery of uncollectible accounts, not yet been written off   $ 4,192    
Mississippi Public Service Commission        
Disaggregation of Revenue [Line Items]        
Recovery of uncollectible accounts, term   2 years   1 year
Reduction to bad debt expense   $ 13,900    
Recovery of uncollectible accounts, previously written off but not yet recovered through rates     $ 9,700  
Recovery of uncollectible accounts, not yet been written off   $ 4,200    
Pipeline and storage segment        
Disaggregation of Revenue [Line Items]        
Regulatory mechanism threshold 75.00%      
v3.25.0.1
Revenue and Accounts Receivable - Schedule of Rollforward of Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]    
Beginning balance $ 37,056 $ 40,840
Current period provisions 8,623 6,750
Write-offs charged against allowance (7,447) (8,757)
Recoveries of amounts previously written off 934 765
Mississippi recovery of uncollectible accounts   (4,192)
Ending balance $ 39,166 $ 35,406
v3.25.0.1
Debt - Schedule of Long-term Debt Instruments (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
Debt Instrument [Line Items]    
Long-term debt $ 8,435,000 $ 7,785,000
Finance lease obligations 48,486 48,890
Total long-term debt 8,483,486 7,833,890
Less:    
Original issue premium on unsecured senior notes and debentures (4,135) (9,071)
Debt issuance cost 62,566 57,664
Current maturities of long-term debt 11,681 1,651
Total long-term debt, net $ 8,413,374 7,783,646
Unsecured 3.00% Senior Notes, due June 2027    
Debt Instrument [Line Items]    
Interest rate 3.00%  
Long-term debt $ 500,000 500,000
Unsecured 2.625% Senior Notes, due September 2029    
Debt Instrument [Line Items]    
Interest rate 2.625%  
Long-term debt $ 500,000 500,000
Unsecured 1.50% Senior Notes, due January 2031    
Debt Instrument [Line Items]    
Interest rate 1.50%  
Long-term debt $ 600,000 600,000
Unsecured 5.45% Senior Notes, due October 2032    
Debt Instrument [Line Items]    
Interest rate 5.45%  
Long-term debt $ 300,000 300,000
Unsecured 5.90% Senior Notes, due November 2033    
Debt Instrument [Line Items]    
Interest rate 5.90%  
Long-term debt $ 725,000 725,000
Unsecured 5.95% Senior Notes, due October 2034    
Debt Instrument [Line Items]    
Interest rate 5.95%  
Long-term debt $ 200,000 200,000
Unsecured 5.50% Senior Notes, due June 2041    
Debt Instrument [Line Items]    
Interest rate 5.50%  
Long-term debt $ 400,000 400,000
Unsecured 4.15% Senior Notes, due January 2043    
Debt Instrument [Line Items]    
Interest rate 4.15%  
Long-term debt $ 500,000 500,000
Unsecured 4.125% Senior Notes, due October 2044    
Debt Instrument [Line Items]    
Interest rate 4.125%  
Long-term debt $ 750,000 750,000
Unsecured 4.30% Senior Notes, due October 2048    
Debt Instrument [Line Items]    
Interest rate 4.30%  
Long-term debt $ 600,000 600,000
Unsecured 4.125% Senior Notes, due March 2049    
Debt Instrument [Line Items]    
Interest rate 4.125%  
Long-term debt $ 450,000 450,000
Unsecured 3.375% Senior Notes, due September 2049    
Debt Instrument [Line Items]    
Interest rate 3.375%  
Long-term debt $ 500,000 500,000
Unsecured 2.85% Senior Notes, due February 2052    
Debt Instrument [Line Items]    
Interest rate 2.85%  
Long-term debt $ 600,000 600,000
Unsecured 5.75% Senior Notes, due October 2052    
Debt Instrument [Line Items]    
Interest rate 5.75%  
Long-term debt $ 500,000 500,000
Unsecured 6.20% Senior Notes, due November 2053    
Debt Instrument [Line Items]    
Interest rate 6.20%  
Long-term debt $ 500,000 500,000
Unsecured 5.00% Senior Notes, due December 2054    
Debt Instrument [Line Items]    
Interest rate 5.00%  
Long-term debt $ 650,000 0
Medium-term note Series A, 1995-1, 6.67%, due December 2025    
Debt Instrument [Line Items]    
Interest rate 6.67%  
Long-term debt $ 10,000 10,000
Unsecured 6.75% Debentures, due July 2028    
Debt Instrument [Line Items]    
Interest rate 6.75%  
Long-term debt $ 150,000 $ 150,000
v3.25.0.1
Debt - Narrative (Details)
 3 Months Ended
Oct. 01, 2024
USD ($)
Dec. 31, 2024
USD ($)
creditFacility
Dec. 31, 2023
USD ($)
Sep. 30, 2024
USD ($)
Oct. 10, 2023
USD ($)
Line Of Credit Facility [Line Items]          
Proceeds from issuance of long-term debt   $ 645,372,000 $ 898,275,000    
Maximum debt-to-total-capitalization ratio   70.00%      
Debt-to-total-capitalization ratio   0.41      
Minimum          
Line Of Credit Facility [Line Items]          
Outstanding indebtedness   $ 15,000,000      
Maximum          
Line Of Credit Facility [Line Items]          
Outstanding indebtedness   $ 100,000,000      
Unsecured 5.00% Senior Notes, due December 2054          
Line Of Credit Facility [Line Items]          
Interest rate   5.00%      
Unsecured 5.00% Senior Notes, due December 2054 | Senior Notes          
Line Of Credit Facility [Line Items]          
Debt face amount         $ 650,000,000
Interest rate         5.00%
Effective rate         3.90%
Proceeds from issuance of long-term debt $ 639,400,000        
Five Year Unsecured Revolving Credit Agreement | Commercial Paper          
Line Of Credit Facility [Line Items]          
Maximum borrowing capacity   $ 1,500,000,000      
Debt agreement term   5 years      
Five Year Unsecured Revolving Credit Agreement, March 28, 2029          
Line Of Credit Facility [Line Items]          
Outstanding commercial paper   $ 0   $ 0  
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Minimum | Base Rate          
Line Of Credit Facility [Line Items]          
Interest rate spread   0.00%      
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Minimum | Term SOFR          
Line Of Credit Facility [Line Items]          
Interest rate spread   0.75%      
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Maximum | Base Rate          
Line Of Credit Facility [Line Items]          
Interest rate spread   0.25%      
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Maximum | Term SOFR          
Line Of Credit Facility [Line Items]          
Interest rate spread   1.25%      
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Commercial Paper          
Line Of Credit Facility [Line Items]          
Maximum borrowing capacity   $ 1,500,000,000      
Accordion feature   250,000,000      
Maximum borrowing capacity post accordion feature   1,750,000,000      
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Revolving Credit Facility          
Line Of Credit Facility [Line Items]          
Maximum borrowing capacity   $ 3,100,000,000      
Number of credit facilities | creditFacility   4      
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility          
Line Of Credit Facility [Line Items]          
Maximum borrowing capacity   $ 1,500,000,000      
Debt agreement term   3 years      
Accordion feature   $ 250,000,000      
Maximum borrowing capacity post accordion feature   1,750,000,000      
Outstanding borrowings   $ 0   0  
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Base Rate          
Line Of Credit Facility [Line Items]          
Interest rate spread   0.00%      
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Term SOFR          
Line Of Credit Facility [Line Items]          
Interest rate spread   0.75%      
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Base Rate          
Line Of Credit Facility [Line Items]          
Interest rate spread   0.25%      
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Term SOFR          
Line Of Credit Facility [Line Items]          
Interest rate spread   1.25%      
$50 Million Bank Loan Agreement | Line of Credit          
Line Of Credit Facility [Line Items]          
Maximum borrowing capacity   $ 50,000,000      
Debt agreement term   364 days      
Outstanding borrowings   $ 0   $ 0  
$50 Million Revolving Credit Facility          
Line Of Credit Facility [Line Items]          
Outstanding borrowings   0      
$50 Million Revolving Credit Facility | Revolving Credit Facility          
Line Of Credit Facility [Line Items]          
Maximum borrowing capacity   $ 50,000,000      
Debt agreement term   364 days      
Remaining borrowing capacity   $ 44,400,000      
v3.25.0.1
Shareholders' Equity - Schedule of Components of Equity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Common stock outstanding, beginning balance (in shares) 155,258,845  
Shareholders' equity, beginning balance $ 12,157,669 $ 10,870,064
Net income 351,858 311,292
Other comprehensive income (loss) 16,423 (49,936)
Cash dividends (135,453) (119,898)
Public and other stock offerings 383,537 257,768
Stock-based compensation plans $ 6,447 3,919
Common stock outstanding, ending balance (in shares) 158,726,065  
Shareholders' equity, ending balance $ 12,780,481 $ 11,273,209
Cash dividends per share (USD per share) $ 0.870 $ 0.805
Common stock    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Common stock outstanding, beginning balance (in shares) 155,258,845 148,492,783
Shareholders' equity, beginning balance $ 776 $ 742
Public and other stock offerings (in shares) 3,329,358 2,177,864
Public and other stock offerings $ 17 $ 11
Stock-based compensation plans (in shares) 137,862 163,750
Stock-based compensation plans $ 1 $ 1
Common stock outstanding, ending balance (in shares) 158,726,065 150,834,397
Shareholders' equity, ending balance $ 794 $ 754
Additional Paid-in Capital    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Shareholders' equity, beginning balance 7,474,559 6,684,120
Public and other stock offerings 383,520 257,757
Stock-based compensation plans 6,446 3,918
Shareholders' equity, ending balance 7,864,525 6,945,795
Accumulated Other Comprehensive Income (Loss)    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Shareholders' equity, beginning balance 465,715 518,528
Other comprehensive income (loss) 16,423 (49,936)
Shareholders' equity, ending balance 482,138 468,592
Retained Earnings    
Increase (Decrease) in Stockholders' Equity [Roll Forward]    
Shareholders' equity, beginning balance 4,216,619 3,666,674
Net income 351,858 311,292
Cash dividends (135,453) (119,898)
Shareholders' equity, ending balance $ 4,433,024 $ 3,858,068
v3.25.0.1
Shareholders' Equity - Narrative (Details) - USD ($)
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 03, 2024
Class of Stock [Line Items]      
Forward sales equity agreement, settlement in cash $ 1,475,770,000    
Net proceeds from equity issuances 379,490,000 $ 254,022,000  
Shelf Registration Statement      
Class of Stock [Line Items]      
Debt and equity securities authorized for issuance     $ 8,000,000,000.0
Debt and equity securities authorized for issuance value remaining 6,300,000,000    
At-The-Market      
Class of Stock [Line Items]      
Value of shares authorized for issuance $ 1,700,000,000    
Forward sales equity agreement (in shares) 3,397,596    
Forward sales equity agreement, settlement in cash $ 476,000,000.0    
Shares issued (in shares) 3,300,904    
Net proceeds from equity issuances $ 379,500,000    
Equity available for issuance $ 1,200,000,000    
v3.25.0.1
Shareholders' Equity - Schedule of Forward Sales Agreement (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended
Dec. 31, 2024
USD ($)
$ / shares
shares
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 11,386,812
Net proceeds available | $ $ 1,475,770
Forward price (USD per share) | $ / shares $ 129.60
Forward Sales Equity Agreement Maturing Quarter Ended June 30, 2025  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 630,514
Net proceeds available | $ $ 73,312
Forward price (USD per share) | $ / shares $ 116.27
Forward Sales Equity Agreement Maturing Quarter Ended September 30, 2025  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 815,655
Net proceeds available | $ $ 96,179
Forward price (USD per share) | $ / shares $ 117.92
Forward Sales Equity Agreement Maturing Quarter Ended December 31, 2025  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 2,344,567
Net proceeds available | $ $ 297,079
Forward price (USD per share) | $ / shares $ 126.71
Forward Sales Equity Agreement Maturing Quarter Ended March 31, 2026  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 3,627,033
Net proceeds available | $ $ 462,383
Forward price (USD per share) | $ / shares $ 127.48
Forward Sales Equity Agreement Maturing Quarter June 30, 2026  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 669,043
Net proceeds available | $ $ 88,951
Forward price (USD per share) | $ / shares $ 132.95
Forward Sales Equity Agreement Maturing Quarter December 31, 2026  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 3,300,000
Net proceeds available | $ $ 457,866
Forward price (USD per share) | $ / shares $ 138.75
v3.25.0.1
Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Shareholders' equity, beginning balance $ 12,157,669 $ 10,870,064
Other comprehensive income (loss) before reclassifications 19,581 (47,445)
Amounts reclassified from accumulated other comprehensive income (3,158) (2,491)
Total other comprehensive income (loss) 16,423 (49,936)
Shareholders' equity, ending balance 12,780,481 11,273,209
Available- for-Sale Securities    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Shareholders' equity, beginning balance 213 (369)
Other comprehensive income (loss) before reclassifications (138) 296
Amounts reclassified from accumulated other comprehensive income 0 0
Total other comprehensive income (loss) (138) 296
Shareholders' equity, ending balance 75 (73)
Interest Rate Agreement Cash Flow Hedges    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Shareholders' equity, beginning balance 465,502 518,897
Other comprehensive income (loss) before reclassifications 19,719 (47,741)
Amounts reclassified from accumulated other comprehensive income (3,158) (2,491)
Total other comprehensive income (loss) 16,561 (50,232)
Shareholders' equity, ending balance 482,063 468,665
Accumulated Other Comprehensive Income (Loss)    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Shareholders' equity, beginning balance 465,715 518,528
Total other comprehensive income (loss) 16,423 (49,936)
Shareholders' equity, ending balance $ 482,138 $ 468,592
v3.25.0.1
Securitization - Narrative (Details) - USD ($)
$ in Thousands
 1 Months Ended
Mar. 31, 2023
Dec. 31, 2024
Sep. 30, 2024
Jun. 30, 2023
Variable Interest Entity [Line Items]        
Long-term debt, fair value   $ 7,484,877 $ 7,337,936  
Variable Interest Entity, Primary Beneficiary | Texas | Extraordinary Gas Cost | Winter Storm Uri        
Variable Interest Entity [Line Items]        
Regulatory asset, authorized $ 3,500,000      
Variable Interest Entity, Primary Beneficiary | Texas | Extraordinary Gas Cost | Winter Storm Uri | Minimum        
Variable Interest Entity [Line Items]        
Regulatory asset, maturity period 12 years      
Variable Interest Entity, Primary Beneficiary | Texas | Extraordinary Gas Cost | Winter Storm Uri | Maximum        
Variable Interest Entity [Line Items]        
Regulatory asset, maturity period 18 years      
Securitized Utility Tariff Bonds | Senior Notes | Variable Interest Entity, Primary Beneficiary        
Variable Interest Entity [Line Items]        
Debt face amount       $ 95,000
Long-term debt   85,100    
Long-term debt, fair value   $ 85,000    
v3.25.0.1
Securitization - Schedule of Condensed Consolidated Balance Sheet (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents $ 4,870 $ 1,516
Other current assets 456,816 288,068
Securitized intangible asset, net 80,580 82,844
Current maturities of securitized long-term debt 8,207 8,207
Securitized long-term debt 76,871 76,871
Variable Interest Entity, Primary Beneficiary    
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents 4,870 1,516
Other current assets 12 3
Securitized intangible asset, net 80,580 82,844
Accrued interest 1,462 365
Current maturities of securitized long-term debt 8,207 8,207
Securitized long-term debt $ 76,871 $ 76,871
v3.25.0.1
Securitization - Schedule of Consolidated Statement of Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Variable Interest Entity [Line Items]    
Operating revenues $ 1,175,999 $ 1,158,467
Operation and maintenance expense (207,044) (166,345)
Amortization expense (180,533) (164,608)
Interest expense, net (52,925) (51,875)
Income before income taxes 431,189 365,116
Variable Interest Entity, Primary Beneficiary    
Variable Interest Entity [Line Items]    
Operating revenues 3,393 3,333
Operation and maintenance expense (61) 0
Amortization expense (2,264) (2,166)
Interest expense, net (1,068) (1,167)
Income before income taxes $ 0 $ 0
v3.25.0.1
Interim Pension and Other Postretirement Benefit Plan Information - Schedule of Components of Net Periodic Pension Cost (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Pension Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Service cost $ 2,837 $ 2,389
Interest cost 6,663 7,497
Expected return on assets (7,655) (7,202)
Amortization of prior service cost (credit) 0 0
Amortization of actuarial (gain) loss 256 118
Settlement 0 776
Net periodic pension cost 2,101 3,578
Other Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 2,033 1,507
Interest cost 3,365 3,509
Expected return on assets (3,831) (3,128)
Amortization of prior service cost (credit) (3,260) (3,260)
Amortization of actuarial (gain) loss (2,429) (2,718)
Settlement 0 0
Net periodic pension cost $ (4,122) $ (4,090)
v3.25.0.1
Commitments and Contingencies (Details)
 3 Months Ended
Jan. 27, 2024
fatality
incident
Dec. 31, 2024
$ / Mcf
MMcf
Dec. 02, 2024
fatality
National Transportation Safety Board | Jackson, Mississippi      
Long-term Purchase Commitment [Line Items]      
Number of incidents investigated that occurred during period | incident 2    
Number of fatalities under investigation | fatality 1    
National Transportation Safety Board | Avondale, Louisiana      
Long-term Purchase Commitment [Line Items]      
Number of fatalities under investigation | fatality     1
Supply Commitment      
Long-term Purchase Commitment [Line Items]      
Contract term   1 year  
Purchase commitment volume   3,900  
Supply Commitment | Weighted Average      
Long-term Purchase Commitment [Line Items]      
Fixed price contracts (USD per Mcf) | $ / Mcf   3.26  
Supply Commitment | Short-term Contract with Customer      
Long-term Purchase Commitment [Line Items]      
Contract term   1 year  
Purchase commitment volume   55,500  
Supply Commitment | Long-term Contract with Customer Within Two To Three Years      
Long-term Purchase Commitment [Line Items]      
Purchase commitment volume   29,900  
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Minimum      
Long-term Purchase Commitment [Line Items]      
Contract term   2 years  
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Maximum      
Long-term Purchase Commitment [Line Items]      
Contract term   3 years  
v3.25.0.1
Income Taxes (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Sep. 30, 2024
Income Tax Contingency [Line Items]      
Effective income tax rate 18.40% 14.70%  
Regulatory liabilities $ 1,223,408   $ 1,227,882
Regulatory excess deferred taxes      
Income Tax Contingency [Line Items]      
Deferred tax liabilities, net 198,800    
Regulatory liabilities 249,790   257,001
Regulatory excess deferred taxes | Other Current Liabilities      
Income Tax Contingency [Line Items]      
Deferred tax liabilities, net 76,800   $ 79,700
Regulatory excess deferred taxes, to be returned, tranche one      
Income Tax Contingency [Line Items]      
Deferred tax liabilities, net $ 135,300    
Regulatory excess deferred taxes, to be returned, tranche one | Minimum      
Income Tax Contingency [Line Items]      
Return basis, term 12 months    
Regulatory excess deferred taxes, to be returned, tranche one | Maximum      
Income Tax Contingency [Line Items]      
Return basis, term 60 months    
Regulatory excess deferred taxes, to be returned, tranche two      
Income Tax Contingency [Line Items]      
Regulatory liabilities $ 49,000    
Regulatory excess deferred taxes, to be returned, tranche two | Minimum      
Income Tax Contingency [Line Items]      
Return basis, term 15 years    
Regulatory excess deferred taxes, to be returned, tranche two | Maximum      
Income Tax Contingency [Line Items]      
Return basis, term 68 years    
Regulatory excess deferred taxes, to be returned, tranche three      
Income Tax Contingency [Line Items]      
Deferred tax liabilities, net $ 14,500    
v3.25.0.1
Financial Instruments - Narrative (Details)
 3 Months Ended
Dec. 31, 2024
USD ($)
MMcf
Dec. 31, 2023
USD ($)
Sep. 30, 2024
USD ($)
Derivative [Line Items]      
Purchase commitment volume | MMcf 15,053    
Contract netting $ 0   $ 0
Cash collateral 0   $ 0
Net (gain) loss on settled interest rate agreements (5,100,000) $ (3,200,000)  
Net realized gains in AOCI $ 391,000,000.0    
Designated As Hedge | Gas Purchases | Commodity contracts      
Derivative [Line Items]      
Purchase commitment volume | MMcf 24,000.0    
Designated As Hedge | Gas Purchases | Commodity contracts | Minimum      
Derivative [Line Items]      
Hedging percent 25.00%    
Designated As Hedge | Gas Purchases | Commodity contracts | Maximum      
Derivative [Line Items]      
Hedging percent 50.00%    
v3.25.0.1
Financial Instruments - Schedule of Interest Rate Risk Management Activities (Details) - Cash Flow Hedging - Designated As Hedge
$ in Thousands
Dec. 31, 2024
USD ($)
Forward Interest Rate Swap  
Derivative [Line Items]  
Derivative notional amount $ 300,000
Forward Interest Rate Swap, Planned Issued Fiscal 2026  
Derivative [Line Items]  
Derivative notional amount $ 300,000
v3.25.0.1
Financial Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets $ 120,951 $ 96,288
Gross/net financial instruments, liabilities (4,063) (7,637)
Designated As Hedges:    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 117,154 91,981
Gross/net financial instruments, liabilities 0 0
Designated As Hedges: | Interest rate contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 117,154 91,981
Gross/net financial instruments, liabilities 0 0
Not Designated As Hedges:    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 3,797 4,307
Gross/net financial instruments, liabilities (4,063) (7,637)
Not Designated As Hedges: | Other current assets | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 2,459 2,091
Not Designated As Hedges: | Other current liabilities | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities (4,063) (7,324)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 1,338 2,216
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities $ 0 $ (313)
v3.25.0.1
Financial Instruments - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Increase (decrease) in fair value:    
Interest rate agreements $ 19,719 $ (47,741)
Recognition of (gains) losses in earnings due to settlements:    
Interest rate agreements (3,158) (2,491)
Total other comprehensive income (loss) from hedging, net of tax $ 16,561 $ (50,232)
v3.25.0.1
Financial Instruments - Schedule Of Expected Deferred Gains (Losses) Recognition (Details)
$ in Thousands
 3 Months Ended
Dec. 31, 2024
USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Next twelve months $ 15,925
Thereafter 375,062
Total $ 390,987
v3.25.0.1
Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments net assets $ 120,951 $ 96,288
Debt and equity securities 109,564 110,594
Total assets 230,515 206,882
Financial instruments net liability 4,063 7,637
Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 27,344 28,311
Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 40,332 40,341
Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Debt securities 39,381 39,142
Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 2,507 2,800
Quoted Prices in Active Markets (Level 1)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments gross assets 0 0
Debt and equity securities 67,676 68,652
Total assets 67,676 68,652
Financial instruments gross liability 0 0
Quoted Prices in Active Markets (Level 1) | Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 27,344 28,311
Quoted Prices in Active Markets (Level 1) | Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 40,332 40,341
Quoted Prices in Active Markets (Level 1) | Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Debt securities 0 0
Quoted Prices in Active Markets (Level 1) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Observable Inputs (Level 2)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments gross assets 120,951 96,288
Debt and equity securities 41,888 41,942
Total assets 162,839 138,230
Financial instruments gross liability 4,063 7,637
Significant Other Observable Inputs (Level 2) | Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Observable Inputs (Level 2) | Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Observable Inputs (Level 2) | Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Debt securities 39,381 39,142
Significant Other Observable Inputs (Level 2) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 2,507 2,800
Significant Other Unobservable Inputs (Level 3)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments gross assets 0 0
Debt and equity securities 0 0
Total assets 0 0
Financial instruments gross liability 0 0
Significant Other Unobservable Inputs (Level 3) | Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Unobservable Inputs (Level 3) | Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Unobservable Inputs (Level 3) | Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Debt securities 0 0
Significant Other Unobservable Inputs (Level 3) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities $ 0 $ 0
v3.25.0.1
Fair Value Measurements - Narrative (Details) - USD ($)
Dec. 31, 2024
Sep. 30, 2024
Fair Value Disclosures [Abstract]    
Allowance for credit losses $ 0  
Cost basis $ 39,300,000 $ 38,900,000
v3.25.0.1
Fair Value Measurements - Schedule of Debt Instruments (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Sep. 30, 2024
Fair Value Disclosures [Abstract]    
Carrying Amount $ 8,435,000 $ 7,785,000
Fair Value $ 7,484,877 $ 7,337,936