ATMOS ENERGY CORP, 10-Q filed on 8/7/2024
Quarterly Report
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Cover Page - shares
 9 Months Ended
Jun. 30, 2024
Aug. 02, 2024
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 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)   155,232,827
Entity Central Index Key 0000731802  
Current Fiscal Year End Date --09-30  
Document Fiscal Year Focus 2024  
Document Fiscal Period Focus Q3  
Amendment Flag false  
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CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
ASSETS    
Property, plant and equipment $ 24,979,631 $ 22,898,374
Less accumulated depreciation and amortization 3,557,513 3,291,791
Net property, plant and equipment 21,422,118 19,606,583
Current assets    
Cash and cash equivalents 674,620 15,404
Restricted cash and cash equivalents 4,642 3,844
Cash and cash equivalents and restricted cash and cash equivalents 679,262 19,248
Accounts receivable, net 391,551 328,654
Gas stored underground 157,912 245,830
Other current assets 479,840 292,036
Total current assets 1,708,565 885,768
Securitized intangible asset, net (See Note 9) 84,998 92,202
Goodwill 731,257 731,257
Deferred charges and other assets 944,313 1,201,158
Total assets 24,891,251 22,516,968
Shareholders’ equity    
Common stock, no par value (stated at $0.005 per share); 200,000,000 shares authorized; issued and outstanding: June 30, 2024 — 155,229,024 shares; September 30, 2023 — 148,492,783 shares 776 742
Additional paid-in capital 7,463,334 6,684,120
Accumulated other comprehensive income 510,132 518,528
Retained earnings 4,208,834 3,666,674
Shareholders’ equity 12,183,076 10,870,064
Long-term debt, net 7,785,196 6,554,133
Securitized long-term debt (See Note 9) 81,261 85,078
Total capitalization 20,049,533 17,509,275
Current liabilities    
Accounts payable and accrued liabilities 319,361 336,083
Other current liabilities 655,944 763,086
Short-term debt 0 241,933
Current maturities of long-term debt 1,620 1,568
Current maturities of securitized long-term debt (See Note 9) 8,001 9,922
Total current liabilities 984,926 1,352,592
Deferred income taxes 2,549,829 2,304,974
Regulatory excess deferred taxes 195,505 253,212
Regulatory cost of removal obligation 515,629 497,017
Deferred credits and other liabilities 595,829 599,898
Total capitalization and liabilities $ 24,891,251 $ 22,516,968
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CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares
Jun. 30, 2024
Sep. 30, 2023
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) 155,229,024 148,492,783
Common stock outstanding (in shares) 155,229,024 148,492,783
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CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
shares in Thousands, $ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Operating revenues $ 701,549 $ 662,733 $ 3,507,243 $ 3,687,715
Purchased gas cost (2,593) 44,550 960,571 1,449,010
Operation and maintenance expense 211,309 195,049 577,553 574,781
Depreciation and amortization expense 166,827 150,726 496,522 445,063
Taxes, other than income 105,739 103,155 302,235 305,784
Operating income 220,267 169,253 1,170,362 913,077
Other non-operating income 19,898 16,170 54,471 54,767
Interest charges 41,160 31,334 148,477 105,464
Income before income taxes 199,005 154,089 1,076,356 862,380
Income tax expense 33,441 16,282 167,477 95,042
Net income $ 165,564 $ 137,807 $ 908,879 $ 767,338
Basic net income per share (USD per share) $ 1.08 $ 0.94 $ 6.00 $ 5.33
Diluted net income per share (USD per share) 1.08 0.94 6.00 5.33
Cash dividends per share (USD per share) $ 0.805 $ 0.740 $ 2.415 $ 2.220
Basic weighted average shares outstanding (in shares) 153,309 146,051 151,459 143,938
Diluted weighted average shares outstanding (in shares) 153,396 146,067 151,497 143,998
Other comprehensive income (loss), net of tax        
Net unrealized holding gains (losses) on available-for-sale securities, net of tax $ (4) $ (121) $ 242 $ 100
Cash flow hedges:        
Amortization and unrealized gains (losses) on interest rate agreements, net of tax 14,436 43,527 (8,638) 35,191
Total other comprehensive income (loss) 14,432 43,406 (8,396) 35,291
Total comprehensive income 179,996 181,213 900,483 802,629
Distribution segment        
Operating revenues 632,446 615,259 3,325,459 3,554,389
Pipeline and storage segment        
Operating revenues 69,103 47,474 181,784 133,326
Operating Segments | Distribution segment        
Operating revenues 633,211 616,067 3,327,730 3,556,703
Purchased gas cost 179,510 206,048 1,464,815 1,896,986
Operation and maintenance expense 153,140 138,351 435,711 426,173
Depreciation and amortization expense 122,912 107,809 363,981 319,783
Taxes, other than income 94,527 92,180 273,430 275,002
Operating income 83,122 71,679 789,793 638,759
Other non-operating income 11,452 6,695 26,650 20,934
Interest charges 22,550 16,146 93,915 60,405
Income before income taxes 72,024 62,228 722,528 599,288
Income tax expense 6,175 2,589 92,550 56,707
Net income 65,849 59,639 629,978 542,581
Operating Segments | Pipeline and storage segment        
Operating revenues 250,680 208,225 685,336 579,278
Purchased gas cost (19) (194) 825 (431)
Operation and maintenance expense 58,427 56,953 142,596 149,329
Depreciation and amortization expense 43,915 42,917 132,541 125,280
Taxes, other than income 11,212 10,975 28,805 30,782
Operating income 137,145 97,574 380,569 274,318
Other non-operating income 8,446 9,475 27,821 33,833
Interest charges 18,610 15,188 54,562 45,059
Income before income taxes 126,981 91,861 353,828 263,092
Income tax expense 27,266 13,693 74,927 38,335
Net income 99,715 78,168 278,901 224,757
Intersegment eliminations        
Operating revenues (182,342) (161,559) (505,823) (448,266)
Purchased gas cost (182,084) (161,304) (505,069) (447,545)
Operation and maintenance expense (258) (255) (754) (721)
Depreciation and amortization expense 0 0 0 0
Taxes, other than income 0 0 0 0
Operating income 0 0 0 0
Other non-operating income 0 0 0 0
Interest charges 0 0 0 0
Income before income taxes 0 0 0 0
Income tax expense 0 0 0 0
Net income 0 0 0 0
Intersegment eliminations | Distribution segment        
Operating revenues (765) (808) (2,271) (2,314)
Intersegment eliminations | Pipeline and storage segment        
Operating revenues $ (181,577) $ (160,751) $ (503,552) $ (445,952)
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CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Income Statement [Abstract]        
Net unrealized holding gains (losses) on available-for-sale securities, tax $ (1) $ (35) $ 70 $ 29
Amortization and unrealized gains (losses) on interest rate agreements, net $ 4,173 $ 12,580 $ (2,496) $ 10,171
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CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands
 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Cash Flows From Operating Activities    
Net income $ 908,879 $ 767,338
Adjustments to reconcile net income to net cash provided by operating activities:    
Depreciation and amortization expense 496,522 445,063
Deferred income taxes 138,658 75,407
Other (39,418) (38,360)
Net assets / liabilities from risk management activities 2,292 (1,545)
Net change in Winter Storm Uri current regulatory asset 0 2,021,889
Net change in other operating assets and liabilities (103,869) (48,284)
Net cash provided by operating activities 1,403,064 3,221,508
Cash Flows From Investing Activities    
Capital expenditures (2,129,137) (2,083,486)
Debt and equity securities activities, net (1,701) (7,302)
Other, net 11,744 13,469
Net cash used in investing activities (2,119,094) (2,077,319)
Cash Flows From Financing Activities    
Net decrease in short-term debt (241,933) (184,967)
Net proceeds from equity issuances 749,987 671,630
Issuance of common stock through stock purchase and employee retirement plans 11,390 11,660
Proceeds from issuance of long-term debt 1,240,204 797,258
Proceeds from issuance of securitized long-term debt by AEK 0 95,000
Proceeds from term loan 0 2,020,000
Repayment of term loan 0 (2,020,000)
Repayment of long-term debt 0 (2,200,000)
Repayment of securitized long-term debt by AEK (5,738) 0
Cash dividends paid (366,719) (319,074)
Debt issuance costs (11,147) (7,864)
Securitized debt issuance costs 0 (1,273)
Net cash provided by (used in) financing activities 1,376,044 (1,137,630)
Net increase in cash and cash equivalents and restricted cash and cash equivalents 660,014 6,559
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period 19,248 51,554
Cash and cash equivalents and restricted cash and cash equivalents at end of period $ 679,262 $ 58,113
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Nature of Business
 9 Months Ended
Jun. 30, 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 June 30, 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.
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Summary of Significant Accounting Policies
 9 Months Ended
Jun. 30, 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, 2023. 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, 2023. Because of seasonal and other factors, the results of operations for the nine-month period ended June 30, 2024 are not indicative of our results of operations for the full 2024 fiscal year, which ends September 30, 2024.
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, 2023.
During the second quarter of fiscal 2024, we completed our annual goodwill impairment assessment using a qualitative assessment, as permitted under U.S. GAAP. We test for goodwill at the reporting unit level on an annual basis and between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of the reporting unit. Based on the assessment performed, we determined that our goodwill was not impaired.
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.
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Regulation
 9 Months Ended
Jun. 30, 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 June 30, 2024 and September 30, 2023 included the following:
June 30,
2024		September 30,
2023
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$14,033 $20,629 
Infrastructure mechanisms (1)
209,609 229,996 
Winter Storm Uri incremental costs12,549 32,115 
Deferred gas costs68,296 148,297 
Regulatory excess deferred taxes (2)
50,462 47,549 
Recoverable loss on reacquired debt3,112 3,238 
Deferred pipeline record collection costs42,454 54,008 
APT annual System Safety and Integrity Rider35,721 — 
Other15,288 19,096 
$451,524 $554,928 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$283,073 $384,513 
Regulatory cost of removal obligation605,449 582,867 
Deferred gas costs20,188 23,093 
APT annual adjustment mechanism48,544 49,894 
Pension and postretirement benefit costs199,838 215,913 
Other30,280 28,054 
$1,187,372 $1,284,334 
 
(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") and a Kansas legislative change enacted in fiscal 2020. See Note 12 to the condensed consolidated financial statements for further information.
Securitization
Kansas
See Note 9 to the condensed consolidated financial statements for securitization and other information related to Atmos Energy Kansas Securitization I, LLC (AEK).
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.
Additionally, we deferred $32.4 million in carrying costs incurred after September 1, 2022. Effective October 1, 2023, we began recovering a portion of these carrying costs. We have recorded $6.1 million and $21.2 million as a current asset in other current assets as of June 30, 2024 and September 30, 2023. We anticipate recovering the remaining $6.4 million in future regulatory filings and have recorded this amount as a long-term asset in deferred charges and other assets as of June 30, 2024.
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Segment Information
 9 Months Ended
Jun. 30, 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, 2023.
Income statements and capital expenditures for the three and nine months ended June 30, 2024 and 2023 by segment are presented in the following tables:
 Three Months Ended June 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$632,446 $69,103 $— $701,549 
Intersegment revenues765 181,577 (182,342)— 
Total operating revenues633,211 250,680 (182,342)701,549 
Purchased gas cost
179,510 (19)(182,084)(2,593)
Operation and maintenance expense153,140 58,427 (258)211,309 
Depreciation and amortization expense122,912 43,915 — 166,827 
Taxes, other than income94,527 11,212 — 105,739 
Operating income83,122 137,145 — 220,267 
Other non-operating income11,452 8,446 — 19,898 
Interest charges22,550 18,610 — 41,160 
Income before income taxes
72,024 126,981 — 199,005 
Income tax expense6,175 27,266 — 33,441 
Net income$65,849 $99,715 $— $165,564 
Capital expenditures$587,062 $126,549 $— $713,611 
 Three Months Ended June 30, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$615,259 $47,474 $— $662,733 
Intersegment revenues808 160,751 (161,559)— 
Total operating revenues616,067 208,225 (161,559)662,733 
Purchased gas cost
206,048 (194)(161,304)44,550 
Operation and maintenance expense138,351 56,953 (255)195,049 
Depreciation and amortization expense107,809 42,917 — 150,726 
Taxes, other than income92,180 10,975 — 103,155 
Operating income71,679 97,574 — 169,253 
Other non-operating income6,695 9,475 — 16,170 
Interest charges16,146 15,188 — 31,334 
Income before income taxes
62,228 91,861 — 154,089 
Income tax expense2,589 13,693 — 16,282 
Net income$59,639 $78,168 $— $137,807 
Capital expenditures$512,585 $155,552 $— $668,137 
 Nine Months Ended June 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$3,325,459 $181,784 $— $3,507,243 
Intersegment revenues2,271 503,552 (505,823)— 
Total operating revenues3,327,730 685,336 (505,823)3,507,243 
Purchased gas cost
1,464,815 825 (505,069)960,571 
Operation and maintenance expense435,711 142,596 (754)577,553 
Depreciation and amortization expense363,981 132,541 — 496,522 
Taxes, other than income273,430 28,805 — 302,235 
Operating income789,793 380,569 — 1,170,362 
Other non-operating income26,650 27,821 — 54,471 
Interest charges93,915 54,562 — 148,477 
Income before income taxes
722,528 353,828 — 1,076,356 
Income tax expense92,550 74,927 — 167,477 
Net income$629,978 $278,901 $— $908,879 
Capital expenditures$1,659,217 $469,920 $— $2,129,137 
 Nine Months Ended June 30, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$3,554,389 $133,326 $— $3,687,715 
Intersegment revenues2,314 445,952 (448,266)— 
Total operating revenues3,556,703 579,278 (448,266)3,687,715 
Purchased gas cost
1,896,986 (431)(447,545)1,449,010 
Operation and maintenance expense426,173 149,329 (721)574,781 
Depreciation and amortization expense319,783 125,280 — 445,063 
Taxes, other than income275,002 30,782 — 305,784 
Operating income638,759 274,318 — 913,077 
Other non-operating income20,934 33,833 — 54,767 
Interest charges60,405 45,059 — 105,464 
Income before income taxes
599,288 263,092 — 862,380 
Income tax expense56,707 38,335 — 95,042 
Net income$542,581 $224,757 $— $767,338 
Capital expenditures$1,381,118 $702,368 $— $2,083,486 
Balance sheet information at June 30, 2024 and September 30, 2023 by segment is presented in the following tables:
 June 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$15,855,074 $5,567,044 $— $21,422,118 
Total assets$24,067,602 $5,901,759 $(5,078,110)$24,891,251 
 September 30, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$14,402,578 $5,204,005 $— $19,606,583 
Total assets$21,716,467 $5,504,972 $(4,704,471)$22,516,968 
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Earnings Per Share
 9 Months Ended
Jun. 30, 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 and nine months ended June 30, 2024 and 2023 are calculated as follows:
 Three Months Ended June 30Nine Months Ended June 30
 2024202320242023
 (In thousands, except per share amounts)
Basic Earnings Per Share
Net income$165,564 $137,807 $908,879 $767,338 
Less: Income allocated to participating securities
87 83 490 482 
Income available to common shareholders
$165,477 $137,724 $908,389 $766,856 
Basic weighted average shares outstanding
153,309 146,051 151,459 143,938 
Net income per share — Basic
$1.08 $0.94 $6.00 $5.33 
Diluted Earnings Per Share
Income available to common shareholders$165,477 $137,724 $908,389 $766,856 
Effect of dilutive shares
— — — — 
Income available to common shareholders
$165,477 $137,724 $908,389 $766,856 
Basic weighted average shares outstanding
153,309 146,051 151,459 143,938 
Dilutive shares87 16 38 60 
Diluted weighted average shares outstanding
153,396 146,067 151,497 143,998 
Net income per share — Diluted$1.08 $0.94 $6.00 $5.33 
v3.24.2.u1
Revenue and Accounts Receivable
 9 Months Ended
Jun. 30, 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, 2023. 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 and nine months ended June 30, 2024 and 2023.
Three Months Ended June 30, 2024Three Months Ended June 30, 2023
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$384,957 $— $380,099 $— 
Commercial169,508 — 165,930 — 
Industrial21,160 — 23,533 — 
Public authority and other8,177 — 8,562 — 
Total gas sales revenues583,802 — 578,124 — 
Transportation revenues30,773 260,779 27,988 212,322 
Miscellaneous revenues2,681 7,592 2,706 4,397 
Revenues from contracts with customers617,256 268,371 608,818 216,719 
Alternative revenue program revenues11,997 (17,691)6,772 (8,494)
Other revenues3,958 — 477 — 
Total operating revenues$633,211 $250,680 $616,067 $208,225 
Nine Months Ended June 30, 2024Nine Months Ended June 30, 2023
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$2,177,935 $— $2,276,240 $— 
Commercial851,462 — 953,409 — 
Industrial79,810 — 127,792 — 
Public authority and other43,881 — 54,074 — 
Total gas sales revenues3,153,088 — 3,411,515 — 
Transportation revenues102,147 699,243 93,661 597,822 
Miscellaneous revenues9,048 12,796 7,650 8,271 
Revenues from contracts with customers3,264,283 712,039 3,512,826 606,093 
Alternative revenue program revenues51,713 (26,703)42,360 (26,815)
Other revenues11,734 — 1,517 — 
Total operating revenues$3,327,730 $685,336 $3,556,703 $579,278 
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. With the completion of APT's most recent rate case in December 2023, the revenue benchmark was increased from $69.4 million to $106.9 million. 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, 2023. During the nine months ended June 30, 2024, there were no material changes to this policy. Rollforwards of our allowance for uncollectible accounts for the three and nine months ended June 30, 2024 and 2023 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 88 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 June 30, 2024
 (In thousands)
Beginning balance, March 31, 2024$42,705 
Current period provisions3,575 
Write-offs charged against allowance(4,407)
Recoveries of amounts previously written off286 
Ending balance, June 30, 2024
$42,159 
 Three Months Ended June 30, 2023
 (In thousands)
Beginning balance, March 31, 2023$52,751 
Current period provisions1,758 
Write-offs charged against allowance(5,902)
Recoveries of amounts previously written off294 
Ending balance, June 30, 2023
$48,901 
 Nine Months Ended June 30, 2024
 (In thousands)
Beginning balance, September 30, 2023
$40,840 
Current period provisions23,122 
Write-offs charged against allowance(19,023)
Recoveries of amounts previously written off1,412 
Mississippi recovery of uncollectible accounts(4,192)
Ending balance, June 30, 2024
$42,159 
 Nine Months Ended June 30, 2023
 (In thousands)
Beginning balance, September 30, 2022
$49,993 
Current period provisions22,000 
Write-offs charged against allowance(24,656)
Recoveries of amounts previously written off1,564 
Ending balance, June 30, 2023
$48,901 
v3.24.2.u1
Debt
 9 Months Ended
Jun. 30, 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, 2023. Other than as described below, there were no material changes in the terms of our debt instruments during the nine months ended June 30, 2024.
Long-term debt at June 30, 2024 and September 30, 2023 consisted of the following:
June 30, 2024September 30, 2023
 (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 October 2033

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 October 2053
500,000 — 
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 obligations49,283 50,393 
Total long-term debt7,834,283 6,610,393 
Less:
Original issue (premium) discount on unsecured senior notes and debentures(9,418)6,104 
Debt issuance cost56,885 48,588 
Current maturities of long-term debt1,620 1,568 
Total long-term debt, net$7,785,196 $6,554,133 
On October 10, 2023, we completed a public offering of $500 million of 6.20% senior notes due October 2053, with an effective interest rate of 5.56%, after giving effect to the offering costs and settlement of our interest rate swaps, and $400 million of 5.90% senior notes due October 2033, with an effective interest rate of 4.35%, 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 $889.4 million were used for general corporate purposes.
On June 21, 2024, we completed a public offering of $325 million of 5.90% senior notes due October 2033, with an effective interest rate of 5.17%, after giving effect to the estimated offering costs. The net proceeds from the offering, after the underwriting discount and offering expenses as of June 30, 2024, of $339.7 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 was replaced on March 28, 2024, with a new five-year senior unsecured $1.5 billion credit facility that expires on March 28, 2029. This new 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 June 30, 2024, there were no amounts outstanding under our commercial paper program. At September 30, 2023, there was $241.9 million outstanding under our commercial paper program.
We also had a $900 million three-year unsecured revolving credit facility, which was replaced on March 28, 2024, with a new $1.5 billion three-year senior unsecured credit facility, which expires March 28, 2027 and is used to provide additional working capital funding. This new 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 June 30, 2024 and September 30, 2023, there were no borrowings outstanding under this facility.
Additionally, we have a $50 million 364-day unsecured facility, which was renewed April 1, 2024 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of June 30, 2024 and September 30, 2023.
Finally, we have a $50 million 364-day unsecured revolving credit facility, which was renewed March 31, 2024 and is used to issue letters of credit and to provide working capital funding. At June 30, 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 June 30, 2024, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 40 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 June 30, 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.
v3.24.2.u1
Shareholders' Equity
 9 Months Ended
Jun. 30, 2024
Equity [Abstract]  
Shareholders' Equity Shareholders' Equity
The following tables present a reconciliation of changes in stockholders' equity for the three and nine months ended June 30, 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, 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 
Net income— — — — 432,023 432,023 
Other comprehensive income— — — 27,108 — 27,108 
Cash dividends ($0.805 per share)
— — — — (121,667)(121,667)
Common stock issued:
Public and other stock offerings34,687 — 4,025 — — 4,025 
Stock-based compensation plans5,468 — 3,941 — — 3,941 
Balance, March 31, 2024150,874,552 754 6,953,761 495,700 4,168,424 11,618,639 
Net income— — — — 165,564 165,564 
Other comprehensive income— — — 14,432 — 14,432 
Cash dividends ($0.805 per share)
— — — — (125,154)(125,154)
Common stock issued:
Public and other stock offerings4,288,217 22 499,562 — — 499,584 
Stock-based compensation plans66,255 — 10,011 — — 10,011 
Balance, June 30, 2024155,229,024 $776 $7,463,334 $510,132 $4,208,834 $12,183,076 
 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, 2022
140,896,598 $704 $5,838,118 $369,112 $3,211,157 $9,419,091 
Net income— — — — 271,860 271,860 
Other comprehensive income— — — 22,218 — 22,218 
Cash dividends ($0.74 per share)
— — — — (104,552)(104,552)
Common stock issued:
Public and other stock offerings2,147,210 11 223,768 — — 223,779 
Stock-based compensation plans111,953 1 3,877 — — 3,878 
Balance, December 31, 2022143,155,761 716 6,065,763 391,330 3,378,465 9,836,274 
Net income— — — — 357,671 357,671 
Other comprehensive loss— — — (30,333)— (30,333)
Cash dividends ($0.74 per share)
— — — — (106,173)(106,173)
Common stock issued:
Public and other stock offerings1,316,930 6 143,808 — — 143,814 
Stock-based compensation plans11,959 — 3,952 — — 3,952 
Balance, March 31, 2023144,484,650 722 6,213,523 360,997 3,629,963 10,205,205 
Net income— — — — 137,807 137,807 
Other comprehensive income— — — 43,406 — 43,406 
Cash dividends ($0.74 per share)
— — — — (108,349)(108,349)
Common stock issued:
Public and other stock offerings2,754,533 15 315,682 — — 315,697 
Stock-based compensation plans65,355 — 8,615 — — 8,615 
Balance, June 30, 2023147,304,538 $737 $6,537,820 $404,403 $3,659,421 $10,602,381 
Shelf Registration, At-the-Market Equity Sales Program and Equity Issuances
We have a shelf registration statement with the Securities and Exchange Commission (SEC) that allows us to issue up to $5.0 billion in common stock and/or debt securities, which expires March 31, 2026. At June 30, 2024, $1.8 billion of securities were available for issuance under this shelf registration statement.
On May 8, 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 $1.0 billion through March 31, 2026 (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 March 31, 2023.
During the nine months ended June 30, 2024, we executed forward sales under our ATM equity sales program with various forward sellers who borrowed and sold 7,224,450 shares of our common stock at an aggregate price of $833.2 million. During the nine months ended June 30, 2024, we also settled forward sale agreements with respect to 6,401,469 shares that had been borrowed and sold by various forward sellers under the ATM program for net proceeds of $750.0 million. As of June 30, 2024, $845.7 million of equity was available for issuance under our existing ATM program. Additionally, we had $550.7 million in available proceeds from outstanding forward sale agreements, as detailed below.
MaturityShares AvailableNet Proceeds Available
(In thousands)		Forward Price
June 30, 20253,931,418 $450,884 $114.69 
September 30, 2025815,655 95,523 $117.11 
December 31, 202536,933 4,328 $117.18 
Total4,784,006 $550,735 $115.12 
Accumulated Other Comprehensive Income (Loss)
We record deferred gains (losses) in AOCI related to available-for-sale debt securities and interest rate agreement cash flow hedges. Deferred gains (losses) for our available-for-sale debt securities are recognized in earnings upon settlement, while deferred gains (losses) related to our interest rate agreement cash flow hedges are recognized in earnings on a straight-line basis over the life of the related financing. The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss).
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2023$(369)$518,897 $518,528 
Other comprehensive income (loss) before reclassifications242 (1,165)(923)
Amounts reclassified from accumulated other comprehensive income— (7,473)(7,473)
Net current-period other comprehensive income (loss)242 (8,638)(8,396)
June 30, 2024$(127)$510,259 $510,132 
 
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2022$(495)$369,607 $369,112 
Other comprehensive income before reclassifications100 36,781 36,881 
Amounts reclassified from accumulated other comprehensive income— (1,590)(1,590)
Net current-period other comprehensive income100 35,191 35,291 
June 30, 2023$(395)$404,798 $404,403 
v3.24.2.u1
Variable Interest Entity
 9 Months Ended
Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Variable Interest Entity Variable Interest Entity
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 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.
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:
June 30, 2024September 30, 2023
 (In thousands)
Restricted cash and cash equivalents$4,642 $3,844 
Other current assets$14 $11 
Securitized intangible asset, net$84,998 $92,202 
Accrued interest$1,534 $1,374 
Current maturities of securitized long-term debt$8,001 $9,922 
Securitized long-term debt$81,261 $85,078 
The following table summarizes the impact of AEK on our condensed consolidated statement of comprehensive income, for the period indicated:
Three Months Ended June 30, 2024Nine Months Ended June 30, 2024
 
Operating revenues$3,463 $10,265 
Operation and maintenance expense(52)(276)
Amortization expense(2,292)(6,561)
Interest expense, net(1,119)(3,428)
Income before income taxes$— $— 
There were no material impacts to the condensed consolidated statements of comprehensive income for the three and nine months ended June 30, 2023.
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 June 30, 2024 is $89.3 million and $89.2 million.
v3.24.2.u1
Interim Pension and Other Postretirement Benefit Plan Information
 9 Months Ended
Jun. 30, 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 and nine months ended June 30, 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.
In the first quarter of fiscal 2024, due to the retirement of an executive, we recognized a settlement charge of $0.8 million associated with our Supplemental Executive Retirement Plan and revalued the net periodic pension cost for the remainder of fiscal 2024. The revaluation of the net periodic pension cost for our Supplemental Executive Retirement Plan resulted in a decrease in the discount rate, effective November 30, 2023, to 5.82% from 6.17%, which will decrease our net periodic pension cost by approximately $0.4 million for the remainder of the fiscal year.
 Three Months Ended June 30
 Pension BenefitsOther Benefits
 2024202320242023
 (In thousands)
Components of net periodic pension cost:
Service cost$2,405 $2,915 $1,507 $1,546 
Interest cost (1)
7,430 7,265 3,509 3,478 
Expected return on assets (1)
(7,202)(7,278)(3,128)(2,804)
Amortization of prior service cost (credit) (1)
— (30)(3,260)(3,285)
Amortization of actuarial (gain) loss (1)
97 178 (2,718)(1,863)
Settlements (1)
— 1,030 — — 
Net periodic pension cost$2,730 $4,080 $(4,090)$(2,928)
 Nine Months Ended June 30
 Pension BenefitsOther Benefits
2024202320242023
 (In thousands)
Components of net periodic pension cost:
Service cost$7,199 $8,731 $4,521 $4,637 
Interest cost (1)
22,356 21,915 10,526 10,433 
Expected return on assets (1)
(21,606)(21,835)(9,383)(8,411)
Amortization of prior service cost (credit) (1)
— (91)(9,780)(9,856)
Amortization of actuarial (gain) loss (1)
313 506 (8,154)(5,589)
Settlements (1)
776 1,030 — — 
Net periodic pension cost$9,038 $10,256 $(12,270)$(8,786)
(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, 2023.
v3.24.2.u1
Commitments and Contingencies
 9 Months Ended
Jun. 30, 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.
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, 2023. At June 30, 2024, we were committed to purchase 67.8 Bcf within one year and 31.5 Bcf within two to three years under indexed contracts. At June 30, 2024, we were committed to purchase 12.8 Bcf within one year under fixed price contracts with a weighted average price of $3.06 per Mcf.
Rate Regulatory Proceedings
As of June 30, 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 nine months ended June 30, 2024.
v3.24.2.u1
Income Taxes
 9 Months Ended
Jun. 30, 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, 2024 and 2023, adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended June 30, 2024 and 2023 were 16.8% and 10.6% and for the nine months ended June 30, 2024 and 2023 were 15.6% and 11.0%. 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) and a Kansas legislative change enacted in fiscal 2020. Currently, the regulatory excess net deferred tax liability of $232.6 million is being returned over various periods. Of this amount, $180.0 million is being returned to customers over 12 - 60 months. An additional $51.6 million is being returned to customers on a provisional basis over 15 - 69 years until our regulators establish the final refund periods. The refund of the remaining $1.0 million will be addressed in future rate proceedings.
As of June 30, 2024 and September 30, 2023, $87.6 million and $131.3 million is recorded in other current liabilities.
v3.24.2.u1
Financial Instruments
 9 Months Ended
Jun. 30, 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, 2023. During the nine months ended June 30, 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 2023-2024 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 27.6 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 June 30, 2024. These swaps were designated as cash flow hedges at the time the agreements were executed.
Planned Debt Issuance DateAmount Hedged
(In thousands)
Fiscal 2025$600,000 
Fiscal 2026300,000 
$900,000 
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 June 30, 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 June 30, 2024, we had 15,455 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 June 30, 2024 and September 30, 2023. 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 June 30, 2024 and September 30, 2023, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
June 30, 2024
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsOther current assets /
Other current liabilities		$273,551 $— 
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities		104,049 — 
Total377,600 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		2,349 (5,928)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		1,271 (49)
Total3,620 (5,977)
Gross / Net Financial Instruments$381,220 $(5,977)
 
September 30, 2023
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities		$379,101 $— 
Total379,101 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		4,071 (14,584)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		2,492 (824)
Total6,563 (15,408)
Gross / Net Financial Instruments$385,664 $(15,408)
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 June 30, 2024 and 2023 was $(3.2) million and $(0.7) million and for the nine months ended June 30, 2024 and 2023 was $(9.6) million and $(2.1) 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 and nine months ended June 30, 2024 and 2023.
 Three Months Ended June 30Nine Months Ended June 30
 2024202320242023
 (In thousands)
Increase (decrease) in fair value:
Interest rate agreements$16,926 $44,057 $(1,165)$36,781 
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements(2,490)(530)(7,473)(1,590)
Total other comprehensive income (loss) from hedging, net of tax$14,436 $43,527 $(8,638)$35,191 
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 June 30, 2024, we had $217.3 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 2053. 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$9,965 
Thereafter207,359 
Total$217,324 

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.
v3.24.2.u1
Fair Value Measurements
 9 Months Ended
Jun. 30, 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, 2023. During the nine months ended June 30, 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, 2023.
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 June 30, 2024 and September 30, 2023. 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		June 30, 2024
 (In thousands)
Assets:
Financial instruments$— $381,220 $— $— $381,220 
Debt and equity securities
Registered investment companies26,948 — — — 26,948 
Bond mutual funds39,253 — — — 39,253 
Bonds (2)
— 38,369 — — 38,369 
Money market funds— 3,791 — — 3,791 
Total debt and equity securities66,201 42,160 — — 108,361 
Total assets$66,201 $423,380 $— $— $489,581 
Liabilities:
Financial instruments$— $5,977 $— $— $5,977 

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, 2023
 (In thousands)
Assets:
Financial instruments$— $385,664 $— $— $385,664 
Debt and equity securities
Registered investment companies26,685 — — — 26,685 
Bond mutual funds37,573 — — — 37,573 
Bonds (2)
— 35,507 — — 35,507 
Money market funds— 4,837 — — 4,837 
Total debt and equity securities64,258 40,344 — — 104,602 
Total assets$64,258 $426,008 $— $— $490,266 
Liabilities:
Financial instruments$— $15,408 $— $— $15,408 
 
(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, 2023, 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 June 30, 2024, no allowance for credit losses was recorded for our available-for-sale debt securities. At June 30, 2024 and September 30, 2023, the amortized cost of our available-for-sale debt securities was $38.5 million and $36.0 million. At June 30, 2024, we maintained investments in bonds that have contractual maturity dates ranging from July 2024 through September 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 June 30, 2024 and September 30, 2023:
 June 30, 2024September 30, 2023
 (In thousands)
Carrying Amount$7,785,000 $6,560,000 
Fair Value$6,892,431 $5,402,591 
v3.24.2.u1
Concentration of Credit Risk
 9 Months Ended
Jun. 30, 2024
Risks and Uncertainties [Abstract]  
Concentration of Credit Risk Concentration of Credit Risk
Information regarding our concentration of credit risk is disclosed in Note 18 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2023. During the nine months ended June 30, 2024, there were no material changes in our concentration of credit risk.
v3.24.2.u1
Pay vs Performance Disclosure - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Jun. 30, 2023
Mar. 31, 2023
Dec. 31, 2022
Jun. 30, 2024
Jun. 30, 2023
Pay vs Performance Disclosure                
Net income $ 165,564 $ 432,023 $ 311,292 $ 137,807 $ 357,671 $ 271,860 $ 908,879 $ 767,338
v3.24.2.u1
Insider Trading Arrangements
 3 Months Ended
Jun. 30, 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
v3.24.2.u1
Summary of Significant Accounting Policies (Policies)
 9 Months Ended
Jun. 30, 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.
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, 2023. During the nine months ended June 30, 2024, there were no changes in these methods.
v3.24.2.u1
Regulation (Tables)
 9 Months Ended
Jun. 30, 2024
Regulated Operations [Abstract]  
Schedule of Regulatory Assets
Regulatory assets and liabilities as of June 30, 2024 and September 30, 2023 included the following:
June 30,
2024		September 30,
2023
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$14,033 $20,629 
Infrastructure mechanisms (1)
209,609 229,996 
Winter Storm Uri incremental costs12,549 32,115 
Deferred gas costs68,296 148,297 
Regulatory excess deferred taxes (2)
50,462 47,549 
Recoverable loss on reacquired debt3,112 3,238 
Deferred pipeline record collection costs42,454 54,008 
APT annual System Safety and Integrity Rider35,721 — 
Other15,288 19,096 
$451,524 $554,928 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$283,073 $384,513 
Regulatory cost of removal obligation605,449 582,867 
Deferred gas costs20,188 23,093 
APT annual adjustment mechanism48,544 49,894 
Pension and postretirement benefit costs199,838 215,913 
Other30,280 28,054 
$1,187,372 $1,284,334 
 
(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") and a Kansas legislative change enacted in fiscal 2020. See Note 12 to the condensed consolidated financial statements for further information.
Schedule of Regulatory Liabilities
Regulatory assets and liabilities as of June 30, 2024 and September 30, 2023 included the following:
June 30,
2024		September 30,
2023
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$14,033 $20,629 
Infrastructure mechanisms (1)
209,609 229,996 
Winter Storm Uri incremental costs12,549 32,115 
Deferred gas costs68,296 148,297 
Regulatory excess deferred taxes (2)
50,462 47,549 
Recoverable loss on reacquired debt3,112 3,238 
Deferred pipeline record collection costs42,454 54,008 
APT annual System Safety and Integrity Rider35,721 — 
Other15,288 19,096 
$451,524 $554,928 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$283,073 $384,513 
Regulatory cost of removal obligation605,449 582,867 
Deferred gas costs20,188 23,093 
APT annual adjustment mechanism48,544 49,894 
Pension and postretirement benefit costs199,838 215,913 
Other30,280 28,054 
$1,187,372 $1,284,334 
 
(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") and a Kansas legislative change enacted in fiscal 2020. See Note 12 to the condensed consolidated financial statements for further information.
v3.24.2.u1
Segment Information (Tables)
 9 Months Ended
Jun. 30, 2024
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment
Income statements and capital expenditures for the three and nine months ended June 30, 2024 and 2023 by segment are presented in the following tables:
 Three Months Ended June 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$632,446 $69,103 $— $701,549 
Intersegment revenues765 181,577 (182,342)— 
Total operating revenues633,211 250,680 (182,342)701,549 
Purchased gas cost
179,510 (19)(182,084)(2,593)
Operation and maintenance expense153,140 58,427 (258)211,309 
Depreciation and amortization expense122,912 43,915 — 166,827 
Taxes, other than income94,527 11,212 — 105,739 
Operating income83,122 137,145 — 220,267 
Other non-operating income11,452 8,446 — 19,898 
Interest charges22,550 18,610 — 41,160 
Income before income taxes
72,024 126,981 — 199,005 
Income tax expense6,175 27,266 — 33,441 
Net income$65,849 $99,715 $— $165,564 
Capital expenditures$587,062 $126,549 $— $713,611 
 Three Months Ended June 30, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$615,259 $47,474 $— $662,733 
Intersegment revenues808 160,751 (161,559)— 
Total operating revenues616,067 208,225 (161,559)662,733 
Purchased gas cost
206,048 (194)(161,304)44,550 
Operation and maintenance expense138,351 56,953 (255)195,049 
Depreciation and amortization expense107,809 42,917 — 150,726 
Taxes, other than income92,180 10,975 — 103,155 
Operating income71,679 97,574 — 169,253 
Other non-operating income6,695 9,475 — 16,170 
Interest charges16,146 15,188 — 31,334 
Income before income taxes
62,228 91,861 — 154,089 
Income tax expense2,589 13,693 — 16,282 
Net income$59,639 $78,168 $— $137,807 
Capital expenditures$512,585 $155,552 $— $668,137 
 Nine Months Ended June 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$3,325,459 $181,784 $— $3,507,243 
Intersegment revenues2,271 503,552 (505,823)— 
Total operating revenues3,327,730 685,336 (505,823)3,507,243 
Purchased gas cost
1,464,815 825 (505,069)960,571 
Operation and maintenance expense435,711 142,596 (754)577,553 
Depreciation and amortization expense363,981 132,541 — 496,522 
Taxes, other than income273,430 28,805 — 302,235 
Operating income789,793 380,569 — 1,170,362 
Other non-operating income26,650 27,821 — 54,471 
Interest charges93,915 54,562 — 148,477 
Income before income taxes
722,528 353,828 — 1,076,356 
Income tax expense92,550 74,927 — 167,477 
Net income$629,978 $278,901 $— $908,879 
Capital expenditures$1,659,217 $469,920 $— $2,129,137 
 Nine Months Ended June 30, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Operating revenues from external parties$3,554,389 $133,326 $— $3,687,715 
Intersegment revenues2,314 445,952 (448,266)— 
Total operating revenues3,556,703 579,278 (448,266)3,687,715 
Purchased gas cost
1,896,986 (431)(447,545)1,449,010 
Operation and maintenance expense426,173 149,329 (721)574,781 
Depreciation and amortization expense319,783 125,280 — 445,063 
Taxes, other than income275,002 30,782 — 305,784 
Operating income638,759 274,318 — 913,077 
Other non-operating income20,934 33,833 — 54,767 
Interest charges60,405 45,059 — 105,464 
Income before income taxes
599,288 263,092 — 862,380 
Income tax expense56,707 38,335 — 95,042 
Net income$542,581 $224,757 $— $767,338 
Capital expenditures$1,381,118 $702,368 $— $2,083,486 
Balance sheet information at June 30, 2024 and September 30, 2023 by segment is presented in the following tables:
 June 30, 2024
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$15,855,074 $5,567,044 $— $21,422,118 
Total assets$24,067,602 $5,901,759 $(5,078,110)$24,891,251 
 September 30, 2023
 DistributionPipeline and StorageEliminationsConsolidated
 (In thousands)
Net property, plant and equipment$14,402,578 $5,204,005 $— $19,606,583 
Total assets$21,716,467 $5,504,972 $(4,704,471)$22,516,968 
v3.24.2.u1
Earnings Per Share (Tables)
 9 Months Ended
Jun. 30, 2024
Earnings Per Share [Abstract]  
Schedule of Earnings Per Share, Basic and Diluted
Basic and diluted earnings per share for the three and nine months ended June 30, 2024 and 2023 are calculated as follows:
 Three Months Ended June 30Nine Months Ended June 30
 2024202320242023
 (In thousands, except per share amounts)
Basic Earnings Per Share
Net income$165,564 $137,807 $908,879 $767,338 
Less: Income allocated to participating securities
87 83 490 482 
Income available to common shareholders
$165,477 $137,724 $908,389 $766,856 
Basic weighted average shares outstanding
153,309 146,051 151,459 143,938 
Net income per share — Basic
$1.08 $0.94 $6.00 $5.33 
Diluted Earnings Per Share
Income available to common shareholders$165,477 $137,724 $908,389 $766,856 
Effect of dilutive shares
— — — — 
Income available to common shareholders
$165,477 $137,724 $908,389 $766,856 
Basic weighted average shares outstanding
153,309 146,051 151,459 143,938 
Dilutive shares87 16 38 60 
Diluted weighted average shares outstanding
153,396 146,067 151,497 143,998 
Net income per share — Diluted$1.08 $0.94 $6.00 $5.33 
v3.24.2.u1
Revenue and Accounts Receivable (Tables)
 9 Months Ended
Jun. 30, 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 and nine months ended June 30, 2024 and 2023.
Three Months Ended June 30, 2024Three Months Ended June 30, 2023
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$384,957 $— $380,099 $— 
Commercial169,508 — 165,930 — 
Industrial21,160 — 23,533 — 
Public authority and other8,177 — 8,562 — 
Total gas sales revenues583,802 — 578,124 — 
Transportation revenues30,773 260,779 27,988 212,322 
Miscellaneous revenues2,681 7,592 2,706 4,397 
Revenues from contracts with customers617,256 268,371 608,818 216,719 
Alternative revenue program revenues11,997 (17,691)6,772 (8,494)
Other revenues3,958 — 477 — 
Total operating revenues$633,211 $250,680 $616,067 $208,225 
Nine Months Ended June 30, 2024Nine Months Ended June 30, 2023
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$2,177,935 $— $2,276,240 $— 
Commercial851,462 — 953,409 — 
Industrial79,810 — 127,792 — 
Public authority and other43,881 — 54,074 — 
Total gas sales revenues3,153,088 — 3,411,515 — 
Transportation revenues102,147 699,243 93,661 597,822 
Miscellaneous revenues9,048 12,796 7,650 8,271 
Revenues from contracts with customers3,264,283 712,039 3,512,826 606,093 
Alternative revenue program revenues51,713 (26,703)42,360 (26,815)
Other revenues11,734 — 1,517 — 
Total operating revenues$3,327,730 $685,336 $3,556,703 $579,278 
Schedule of Allowance for Credit Loss Activity Rollforwards of our allowance for uncollectible accounts for the three and nine months ended June 30, 2024 and 2023 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 88 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 June 30, 2024
 (In thousands)
Beginning balance, March 31, 2024$42,705 
Current period provisions3,575 
Write-offs charged against allowance(4,407)
Recoveries of amounts previously written off286 
Ending balance, June 30, 2024
$42,159 
 Three Months Ended June 30, 2023
 (In thousands)
Beginning balance, March 31, 2023$52,751 
Current period provisions1,758 
Write-offs charged against allowance(5,902)
Recoveries of amounts previously written off294 
Ending balance, June 30, 2023
$48,901 
 Nine Months Ended June 30, 2024
 (In thousands)
Beginning balance, September 30, 2023
$40,840 
Current period provisions23,122 
Write-offs charged against allowance(19,023)
Recoveries of amounts previously written off1,412 
Mississippi recovery of uncollectible accounts(4,192)
Ending balance, June 30, 2024
$42,159 
 Nine Months Ended June 30, 2023
 (In thousands)
Beginning balance, September 30, 2022
$49,993 
Current period provisions22,000 
Write-offs charged against allowance(24,656)
Recoveries of amounts previously written off1,564 
Ending balance, June 30, 2023
$48,901 
v3.24.2.u1
Debt (Tables)
 9 Months Ended
Jun. 30, 2024
Debt Disclosure [Abstract]  
Schedule of Long-term Debt Instruments
Long-term debt at June 30, 2024 and September 30, 2023 consisted of the following:
June 30, 2024September 30, 2023
 (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 October 2033

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 October 2053
500,000 — 
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 obligations49,283 50,393 
Total long-term debt7,834,283 6,610,393 
Less:
Original issue (premium) discount on unsecured senior notes and debentures(9,418)6,104 
Debt issuance cost56,885 48,588 
Current maturities of long-term debt1,620 1,568 
Total long-term debt, net$7,785,196 $6,554,133 
v3.24.2.u1
Shareholders' Equity (Tables)
 9 Months Ended
Jun. 30, 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 and nine months ended June 30, 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, 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 
Net income— — — — 432,023 432,023 
Other comprehensive income— — — 27,108 — 27,108 
Cash dividends ($0.805 per share)
— — — — (121,667)(121,667)
Common stock issued:
Public and other stock offerings34,687 — 4,025 — — 4,025 
Stock-based compensation plans5,468 — 3,941 — — 3,941 
Balance, March 31, 2024150,874,552 754 6,953,761 495,700 4,168,424 11,618,639 
Net income— — — — 165,564 165,564 
Other comprehensive income— — — 14,432 — 14,432 
Cash dividends ($0.805 per share)
— — — — (125,154)(125,154)
Common stock issued:
Public and other stock offerings4,288,217 22 499,562 — — 499,584 
Stock-based compensation plans66,255 — 10,011 — — 10,011 
Balance, June 30, 2024155,229,024 $776 $7,463,334 $510,132 $4,208,834 $12,183,076 
 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, 2022
140,896,598 $704 $5,838,118 $369,112 $3,211,157 $9,419,091 
Net income— — — — 271,860 271,860 
Other comprehensive income— — — 22,218 — 22,218 
Cash dividends ($0.74 per share)
— — — — (104,552)(104,552)
Common stock issued:
Public and other stock offerings2,147,210 11 223,768 — — 223,779 
Stock-based compensation plans111,953 1 3,877 — — 3,878 
Balance, December 31, 2022143,155,761 716 6,065,763 391,330 3,378,465 9,836,274 
Net income— — — — 357,671 357,671 
Other comprehensive loss— — — (30,333)— (30,333)
Cash dividends ($0.74 per share)
— — — — (106,173)(106,173)
Common stock issued:
Public and other stock offerings1,316,930 6 143,808 — — 143,814 
Stock-based compensation plans11,959 — 3,952 — — 3,952 
Balance, March 31, 2023144,484,650 722 6,213,523 360,997 3,629,963 10,205,205 
Net income— — — — 137,807 137,807 
Other comprehensive income— — — 43,406 — 43,406 
Cash dividends ($0.74 per share)
— — — — (108,349)(108,349)
Common stock issued:
Public and other stock offerings2,754,533 15 315,682 — — 315,697 
Stock-based compensation plans65,355 — 8,615 — — 8,615 
Balance, June 30, 2023147,304,538 $737 $6,537,820 $404,403 $3,659,421 $10,602,381 
Schedule of Forward Sales Agreements Additionally, we had $550.7 million in available proceeds from outstanding forward sale agreements, as detailed below.
MaturityShares AvailableNet Proceeds Available
(In thousands)		Forward Price
June 30, 20253,931,418 $450,884 $114.69 
September 30, 2025815,655 95,523 $117.11 
December 31, 202536,933 4,328 $117.18 
Total4,784,006 $550,735 $115.12 
Schedule of Accumulated Other Comprehensive Income (Loss) The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss).
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2023$(369)$518,897 $518,528 
Other comprehensive income (loss) before reclassifications242 (1,165)(923)
Amounts reclassified from accumulated other comprehensive income— (7,473)(7,473)
Net current-period other comprehensive income (loss)242 (8,638)(8,396)
June 30, 2024$(127)$510,259 $510,132 
 
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
 (In thousands)
September 30, 2022$(495)$369,607 $369,112 
Other comprehensive income before reclassifications100 36,781 36,881 
Amounts reclassified from accumulated other comprehensive income— (1,590)(1,590)
Net current-period other comprehensive income100 35,191 35,291 
June 30, 2023$(395)$404,798 $404,403 
v3.24.2.u1
Variable Interest Entity (Tables)
 9 Months Ended
Jun. 30, 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:
June 30, 2024September 30, 2023
 (In thousands)
Restricted cash and cash equivalents$4,642 $3,844 
Other current assets$14 $11 
Securitized intangible asset, net$84,998 $92,202 
Accrued interest$1,534 $1,374 
Current maturities of securitized long-term debt$8,001 $9,922 
Securitized long-term debt$81,261 $85,078 
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 June 30, 2024Nine Months Ended June 30, 2024
 
Operating revenues$3,463 $10,265 
Operation and maintenance expense(52)(276)
Amortization expense(2,292)(6,561)
Interest expense, net(1,119)(3,428)
Income before income taxes$— $— 
There were no material impacts to the condensed consolidated statements of comprehensive income for the three and nine months ended June 30, 2023.
v3.24.2.u1
Interim Pension and Other Postretirement Benefit Plan Information (Tables)
 9 Months Ended
Jun. 30, 2024
Retirement Benefits, Description [Abstract]  
Schedule of Net Benefit Costs
 Three Months Ended June 30
 Pension BenefitsOther Benefits
 2024202320242023
 (In thousands)
Components of net periodic pension cost:
Service cost$2,405 $2,915 $1,507 $1,546 
Interest cost (1)
7,430 7,265 3,509 3,478 
Expected return on assets (1)
(7,202)(7,278)(3,128)(2,804)
Amortization of prior service cost (credit) (1)
— (30)(3,260)(3,285)
Amortization of actuarial (gain) loss (1)
97 178 (2,718)(1,863)
Settlements (1)
— 1,030 — — 
Net periodic pension cost$2,730 $4,080 $(4,090)$(2,928)
 Nine Months Ended June 30
 Pension BenefitsOther Benefits
2024202320242023
 (In thousands)
Components of net periodic pension cost:
Service cost$7,199 $8,731 $4,521 $4,637 
Interest cost (1)
22,356 21,915 10,526 10,433 
Expected return on assets (1)
(21,606)(21,835)(9,383)(8,411)
Amortization of prior service cost (credit) (1)
— (91)(9,780)(9,856)
Amortization of actuarial (gain) loss (1)
313 506 (8,154)(5,589)
Settlements (1)
776 1,030 — — 
Net periodic pension cost$9,038 $10,256 $(12,270)$(8,786)
(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, 2023.
v3.24.2.u1
Financial Instruments (Tables)
 9 Months Ended
Jun. 30, 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 June 30, 2024. These swaps were designated as cash flow hedges at the time the agreements were executed.
Planned Debt Issuance DateAmount Hedged
(In thousands)
Fiscal 2025$600,000 
Fiscal 2026300,000 
$900,000 
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 June 30, 2024 and September 30, 2023. 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 June 30, 2024 and September 30, 2023, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
June 30, 2024
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsOther current assets /
Other current liabilities		$273,551 $— 
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities		104,049 — 
Total377,600 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		2,349 (5,928)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		1,271 (49)
Total3,620 (5,977)
Gross / Net Financial Instruments$381,220 $(5,977)
 
September 30, 2023
Balance Sheet LocationAssetsLiabilities
   (In thousands)
Designated As Hedges:
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities		$379,101 $— 
Total379,101 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		4,071 (14,584)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		2,492 (824)
Total6,563 (15,408)
Gross / Net Financial Instruments$385,664 $(15,408)
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 and nine months ended June 30, 2024 and 2023.
 Three Months Ended June 30Nine Months Ended June 30
 2024202320242023
 (In thousands)
Increase (decrease) in fair value:
Interest rate agreements$16,926 $44,057 $(1,165)$36,781 
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements(2,490)(530)(7,473)(1,590)
Total other comprehensive income (loss) from hedging, net of tax$14,436 $43,527 $(8,638)$35,191 
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 2053. 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$9,965 
Thereafter207,359 
Total$217,324 
v3.24.2.u1
Fair Value Measurements (Tables)
 9 Months Ended
Jun. 30, 2024
Fair Value Disclosures [Abstract]  
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of June 30, 2024 and September 30, 2023. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement.
Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)		Netting and
Cash
Collateral		June 30, 2024
 (In thousands)
Assets:
Financial instruments$— $381,220 $— $— $381,220 
Debt and equity securities
Registered investment companies26,948 — — — 26,948 
Bond mutual funds39,253 — — — 39,253 
Bonds (2)
— 38,369 — — 38,369 
Money market funds— 3,791 — — 3,791 
Total debt and equity securities66,201 42,160 — — 108,361 
Total assets$66,201 $423,380 $— $— $489,581 
Liabilities:
Financial instruments$— $5,977 $— $— $5,977 

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, 2023
 (In thousands)
Assets:
Financial instruments$— $385,664 $— $— $385,664 
Debt and equity securities
Registered investment companies26,685 — — — 26,685 
Bond mutual funds37,573 — — — 37,573 
Bonds (2)
— 35,507 — — 35,507 
Money market funds— 4,837 — — 4,837 
Total debt and equity securities64,258 40,344 — — 104,602 
Total assets$64,258 $426,008 $— $— $490,266 
Liabilities:
Financial instruments$— $15,408 $— $— $15,408 
 
(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 June 30, 2024 and September 30, 2023:
 June 30, 2024September 30, 2023
 (In thousands)
Carrying Amount$7,785,000 $6,560,000 
Fair Value$6,892,431 $5,402,591 
v3.24.2.u1
Nature of Business (Details)
customer in Millions
Jun. 30, 2024
customer
state
regulatedDistributionDivision
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Number of customers serviced (over) | customer 3.3
Number of regulated distribution divisions | regulatedDistributionDivision 6
Number of states with service areas | state 8
v3.24.2.u1
Regulation - Schedule of Regulatory Assets and Liabilities (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Regulatory Asset [Line Items]    
Regulatory assets $ 451,524 $ 554,928
Regulatory Liabilities [Line Items]    
Regulatory liabilities 1,187,372 1,284,334
Regulatory excess deferred taxes    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 283,073 384,513
Regulatory cost of removal obligation    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 605,449 582,867
Deferred gas costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 20,188 23,093
APT annual adjustment mechanism    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 48,544 49,894
Pension and postretirement benefit costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 199,838 215,913
Other    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 30,280 28,054
Pension and postretirement benefit costs    
Regulatory Asset [Line Items]    
Regulatory assets 14,033 20,629
Infrastructure mechanisms    
Regulatory Asset [Line Items]    
Regulatory assets 209,609 229,996
Winter Storm Uri incremental costs    
Regulatory Asset [Line Items]    
Regulatory assets 12,549 32,115
Deferred gas costs    
Regulatory Asset [Line Items]    
Regulatory assets 68,296 148,297
Regulatory excess deferred taxes    
Regulatory Asset [Line Items]    
Regulatory assets 50,462 47,549
Recoverable loss on reacquired debt    
Regulatory Asset [Line Items]    
Regulatory assets 3,112 3,238
Deferred pipeline record collection costs    
Regulatory Asset [Line Items]    
Regulatory assets 42,454 54,008
APT annual System Safety and Integrity Rider    
Regulatory Asset [Line Items]    
Regulatory assets 35,721 0
Other    
Regulatory Asset [Line Items]    
Regulatory assets $ 15,288 $ 19,096
v3.24.2.u1
Regulation - Narrative (Details) - Texas - Winter Storm Uri - USD ($)
$ in Millions
 1 Months Ended 9 Months Ended 12 Months Ended
Sep. 01, 2022
Mar. 31, 2023
Jun. 30, 2024
Sep. 30, 2023
Extraordinary Gas Cost        
Regulatory Asset [Line Items]        
Regulatory asset, authorized   $ 3,500.0    
Extraordinary Gas Cost | Minimum        
Regulatory Asset [Line Items]        
Regulatory asset, maturity period   12 years    
Extraordinary Gas Cost | Maximum        
Regulatory Asset [Line Items]        
Regulatory asset, maturity period   18 years    
Winter Storm Uri incremental costs        
Regulatory Asset [Line Items]        
Regulatory asset, deferred costs $ 32.4      
Regulatory asset, deferred costs, remaining     $ 6.4  
Winter Storm Uri incremental costs | Other current assets        
Regulatory Asset [Line Items]        
Regulatory asset, recovering cost     $ 6.1 $ 21.2
v3.24.2.u1
Segment Information - Narrative (Details)
Jun. 30, 2024
state
Segment Reporting [Abstract]  
Number of states with service areas 8
v3.24.2.u1
Segment Information - Schedule of Income Statements and Capital Expenditures By Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Jun. 30, 2023
Mar. 31, 2023
Dec. 31, 2022
Jun. 30, 2024
Jun. 30, 2023
Segment Reporting Information [Line Items]                
Operating revenues $ 701,549     $ 662,733     $ 3,507,243 $ 3,687,715
Purchased gas cost (2,593)     44,550     960,571 1,449,010
Operation and maintenance expense 211,309     195,049     577,553 574,781
Depreciation and amortization expense 166,827     150,726     496,522 445,063
Taxes, other than income 105,739     103,155     302,235 305,784
Operating income 220,267     169,253     1,170,362 913,077
Other non-operating income 19,898     16,170     54,471 54,767
Interest charges 41,160     31,334     148,477 105,464
Income before income taxes 199,005     154,089     1,076,356 862,380
Income tax expense 33,441     16,282     167,477 95,042
Net income 165,564 $ 432,023 $ 311,292 137,807 $ 357,671 $ 271,860 908,879 767,338
Capital expenditures 713,611     668,137     2,129,137 2,083,486
Distribution                
Segment Reporting Information [Line Items]                
Operating revenues 632,446     615,259     3,325,459 3,554,389
Pipeline and Storage                
Segment Reporting Information [Line Items]                
Operating revenues 69,103     47,474     181,784 133,326
Eliminations                
Segment Reporting Information [Line Items]                
Operating revenues (182,342)     (161,559)     (505,823) (448,266)
Purchased gas cost (182,084)     (161,304)     (505,069) (447,545)
Operation and maintenance expense (258)     (255)     (754) (721)
Depreciation and amortization expense 0     0     0 0
Taxes, other than income 0     0     0 0
Operating income 0     0     0 0
Other non-operating income 0     0     0 0
Interest charges 0     0     0 0
Income before income taxes 0     0     0 0
Income tax expense 0     0     0 0
Net income 0     0     0 0
Capital expenditures 0     0     0 0
Eliminations | Distribution                
Segment Reporting Information [Line Items]                
Operating revenues (765)     (808)     (2,271) (2,314)
Eliminations | Pipeline and Storage                
Segment Reporting Information [Line Items]                
Operating revenues (181,577)     (160,751)     (503,552) (445,952)
Operating Segments | Distribution                
Segment Reporting Information [Line Items]                
Operating revenues 633,211     616,067     3,327,730 3,556,703
Purchased gas cost 179,510     206,048     1,464,815 1,896,986
Operation and maintenance expense 153,140     138,351     435,711 426,173
Depreciation and amortization expense 122,912     107,809     363,981 319,783
Taxes, other than income 94,527     92,180     273,430 275,002
Operating income 83,122     71,679     789,793 638,759
Other non-operating income 11,452     6,695     26,650 20,934
Interest charges 22,550     16,146     93,915 60,405
Income before income taxes 72,024     62,228     722,528 599,288
Income tax expense 6,175     2,589     92,550 56,707
Net income 65,849     59,639     629,978 542,581
Capital expenditures 587,062     512,585     1,659,217 1,381,118
Operating Segments | Pipeline and Storage                
Segment Reporting Information [Line Items]                
Operating revenues 250,680     208,225     685,336 579,278
Purchased gas cost (19)     (194)     825 (431)
Operation and maintenance expense 58,427     56,953     142,596 149,329
Depreciation and amortization expense 43,915     42,917     132,541 125,280
Taxes, other than income 11,212     10,975     28,805 30,782
Operating income 137,145     97,574     380,569 274,318
Other non-operating income 8,446     9,475     27,821 33,833
Interest charges 18,610     15,188     54,562 45,059
Income before income taxes 126,981     91,861     353,828 263,092
Income tax expense 27,266     13,693     74,927 38,335
Net income 99,715     78,168     278,901 224,757
Capital expenditures $ 126,549     $ 155,552     $ 469,920 $ 702,368
v3.24.2.u1
Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Segment Reporting Information [Line Items]    
Net property, plant and equipment $ 21,422,118 $ 19,606,583
Total assets 24,891,251 22,516,968
Operating Segments | Distribution    
Segment Reporting Information [Line Items]    
Net property, plant and equipment 15,855,074 14,402,578
Total assets 24,067,602 21,716,467
Operating Segments | Pipeline and Storage    
Segment Reporting Information [Line Items]    
Net property, plant and equipment 5,567,044 5,204,005
Total assets 5,901,759 5,504,972
Eliminations    
Segment Reporting Information [Line Items]    
Net property, plant and equipment 0 0
Total assets $ (5,078,110) $ (4,704,471)
v3.24.2.u1
Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Jun. 30, 2023
Mar. 31, 2023
Dec. 31, 2022
Jun. 30, 2024
Jun. 30, 2023
Basic Earnings Per Share                
Net income $ 165,564 $ 432,023 $ 311,292 $ 137,807 $ 357,671 $ 271,860 $ 908,879 $ 767,338
Less: Income allocated to participating securities 87     83     490 482
Income available to common shareholders $ 165,477     $ 137,724     $ 908,389 $ 766,856
Basic weighted average shares outstanding (in shares) 153,309     146,051     151,459 143,938
Net income per share - Basic (USD per share) $ 1.08     $ 0.94     $ 6.00 $ 5.33
Diluted Earnings Per Share                
Income available to common shareholders $ 165,477     $ 137,724     $ 908,389 $ 766,856
Effect of dilutive shares 0     0     0 0
Income available to common shareholders $ 165,477     $ 137,724     $ 908,389 $ 766,856
Basic weighted average shares outstanding (in shares) 153,309     146,051     151,459 143,938
Dilutive shares (in shares) 87     16     38 60
Diluted weighted average shares outstanding (in shares) 153,396     146,067     151,497 143,998
Net income per share - Diluted (USD per share) $ 1.08     $ 0.94     $ 6.00 $ 5.33
v3.24.2.u1
Revenue and Accounts Receivable - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Disaggregation of Revenue [Line Items]        
Total operating revenues $ 701,549 $ 662,733 $ 3,507,243 $ 3,687,715
Distribution        
Disaggregation of Revenue [Line Items]        
Total operating revenues 632,446 615,259 3,325,459 3,554,389
Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Total operating revenues 69,103 47,474 181,784 133,326
Operating Segments | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 617,256 608,818 3,264,283 3,512,826
Alternative revenue program revenues 11,997 6,772 51,713 42,360
Other revenues 3,958 477 11,734 1,517
Total operating revenues 633,211 616,067 3,327,730 3,556,703
Operating Segments | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 268,371 216,719 712,039 606,093
Alternative revenue program revenues (17,691) (8,494) (26,703) (26,815)
Other revenues 0 0 0 0
Total operating revenues 250,680 208,225 685,336 579,278
Operating Segments | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 583,802 578,124 3,153,088 3,411,515
Operating Segments | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Transportation revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 30,773 27,988 102,147 93,661
Operating Segments | Transportation revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 260,779 212,322 699,243 597,822
Operating Segments | Miscellaneous revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 2,681 2,706 9,048 7,650
Operating Segments | Miscellaneous revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 7,592 4,397 12,796 8,271
Operating Segments | Residential | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 384,957 380,099 2,177,935 2,276,240
Operating Segments | Residential | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Commercial | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 169,508 165,930 851,462 953,409
Operating Segments | Commercial | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Industrial | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 21,160 23,533 79,810 127,792
Operating Segments | Industrial | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Public authority and other | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 8,177 8,562 43,881 54,074
Operating Segments | Public authority and other | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers $ 0 $ 0 $ 0 $ 0
v3.24.2.u1
Revenue and Accounts Receivable - Narrative (Details) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended 9 Months Ended 27 Months Ended
Nov. 30, 2023
Dec. 31, 2023
Jun. 30, 2024
Dec. 31, 2023
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Disaggregation of Revenue [Line Items]                
Percent of customers excluded     88.00%     88.00%    
Reduction to bad debt expense     $ (3,575)   $ (1,758) $ (23,122) $ (22,000)  
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 1 year 2 years   2 years        
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    
Distribution segment                
Disaggregation of Revenue [Line Items]                
Regulatory mechanism threshold           75.00%    
Pipeline and storage segment                
Disaggregation of Revenue [Line Items]                
Rate case revenue benchmark $ 69,400 $ 106,900            
v3.24.2.u1
Revenue and Accounts Receivable - Schedule of Rollforward of Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]        
Beginning balance $ 42,705 $ 52,751 $ 40,840 $ 49,993
Current period provisions 3,575 1,758 23,122 22,000
Write-offs charged against allowance (4,407) (5,902) (19,023) (24,656)
Recoveries of amounts previously written off 286 294 1,412 1,564
Mississippi recovery of uncollectible accounts     (4,192)  
Ending balance $ 42,159 $ 48,901 $ 42,159 $ 48,901
v3.24.2.u1
Debt - Schedule of Long-term Debt Instruments (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Debt Instrument [Line Items]    
Long-term debt $ 7,785,000 $ 6,560,000
Finance lease obligations 49,283 50,393
Total long-term debt 7,834,283 6,610,393
Less:    
Original issue (premium) discount on unsecured senior notes and debentures (9,418) 6,104
Debt issuance cost 56,885 48,588
Current maturities of long-term debt 1,620 1,568
Total long-term debt, net $ 7,785,196 6,554,133
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 October 2033    
Debt Instrument [Line Items]    
Interest rate 5.90%  
Long-term debt $ 725,000 0
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 October 2053    
Debt Instrument [Line Items]    
Interest rate 6.20%  
Long-term debt $ 500,000 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
v3.24.2.u1
Debt - Narrative (Details)
 9 Months Ended
Jun. 30, 2024
USD ($)
creditFacility
Apr. 01, 2024
USD ($)
Mar. 28, 2024
USD ($)
Mar. 27, 2024
USD ($)
Oct. 10, 2023
USD ($)
Jun. 30, 2024
USD ($)
creditFacility
Jun. 30, 2023
USD ($)
Jun. 21, 2024
USD ($)
Sep. 30, 2023
USD ($)
Line Of Credit Facility [Line Items]                  
Proceeds from issuance of long-term debt           $ 1,240,204,000 $ 797,258,000    
Maximum debt-to-total-capitalization ratio           70.00%      
Debt-to-total-capitalization ratio 0.40         0.40      
Minimum                  
Line Of Credit Facility [Line Items]                  
Outstanding indebtedness $ 15,000,000         $ 15,000,000      
Maximum                  
Line Of Credit Facility [Line Items]                  
Outstanding indebtedness $ 100,000,000         $ 100,000,000      
Unsecured Senior Notes Due 2053 and Unsecured Senior Notes Due 2033 | Senior Notes                  
Line Of Credit Facility [Line Items]                  
Proceeds from issuance of long-term debt         $ 889,400,000        
Unsecured 6.20% Senior Notes, due October 2053                  
Line Of Credit Facility [Line Items]                  
Interest rate 6.20%         6.20%      
Unsecured 6.20% Senior Notes, due October 2053 | Senior Notes                  
Line Of Credit Facility [Line Items]                  
Debt face amount         $ 500,000,000        
Interest rate         6.20%        
Effective rate         5.56%        
Unsecured 5.90% Senior Notes, due October 2033                  
Line Of Credit Facility [Line Items]                  
Interest rate 5.90%         5.90%      
Unsecured 5.90% Senior Notes, due October 2033 | Senior Notes                  
Line Of Credit Facility [Line Items]                  
Debt face amount         $ 400,000,000     $ 325,000,000  
Interest rate         5.90%     5.90%  
Effective rate         4.35%     5.17%  
Proceeds from issuance of long-term debt $ 339,700,000                
Five Year Unsecured Revolving Credit Agreement                  
Line Of Credit Facility [Line Items]                  
Outstanding commercial paper                 $ 241,900,000
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   $ 1,500,000,000     $ 1,500,000,000      
Debt agreement term     5 years            
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         $ 3,100,000,000      
Number of credit facilities | creditFacility 4         4      
$900 Million Revolving Credit Facility | Revolving Credit Facility                  
Line Of Credit Facility [Line Items]                  
Maximum borrowing capacity       $ 900,000,000          
Debt agreement term       3 years          
Outstanding borrowings                 0
$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     $ 0
$50 Million Revolving Credit Facility                  
Line Of Credit Facility [Line Items]                  
Outstanding borrowings 0         0      
$50 Million Revolving Credit Facility | Revolving Credit Facility                  
Line Of Credit Facility [Line Items]                  
Maximum borrowing capacity 50,000,000         $ 50,000,000      
Debt agreement term           364 days      
Remaining borrowing capacity $ 44,400,000         $ 44,400,000      
v3.24.2.u1
Shareholders' Equity - Schedule of Components of Equity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Jun. 30, 2023
Mar. 31, 2023
Dec. 31, 2022
Jun. 30, 2024
Jun. 30, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Common stock outstanding, beginning balance (in shares)     148,492,783       148,492,783  
Shareholders' equity, beginning balance $ 11,618,639 $ 11,273,209 $ 10,870,064 $ 10,205,205 $ 9,836,274 $ 9,419,091 $ 10,870,064 $ 9,419,091
Net income 165,564 432,023 311,292 137,807 357,671 271,860 908,879 767,338
Other comprehensive income (loss) 14,432 27,108 (49,936) 43,406 (30,333) 22,218 $ (8,396) 35,291
Cash dividends (125,154) (121,667) (119,898) (108,349) (106,173) (104,552)    
Public and other stock offerings 499,584 4,025 257,768 315,697 143,814 223,779    
Stock-based compensation plans $ 10,011 3,941 3,919 8,615 3,952 3,878    
Common stock outstanding, ending balance (in shares) 155,229,024           155,229,024  
Shareholders' equity, ending balance $ 12,183,076 $ 11,618,639 $ 11,273,209 $ 10,602,381 $ 10,205,205 $ 9,836,274 $ 12,183,076 $ 10,602,381
Cash dividends per share (USD per share) $ 0.805 $ 0.805 $ 0.805 $ 0.740 $ 0.74 $ 0.74 $ 2.415 $ 2.220
Common stock                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Common stock outstanding, beginning balance (in shares) 150,874,552 150,834,397 148,492,783 144,484,650 143,155,761 140,896,598 148,492,783 140,896,598
Shareholders' equity, beginning balance $ 754 $ 754 $ 742 $ 722 $ 716 $ 704 $ 742 $ 704
Public and other stock offerings (in shares) 4,288,217 34,687 2,177,864 2,754,533 1,316,930 2,147,210    
Public and other stock offerings $ 22   $ 11 $ 15 $ 6 $ 11    
Stock-based compensation plans (in shares) 66,255 5,468 163,750 65,355 11,959 111,953    
Stock-based compensation plans     $ 1     $ 1    
Common stock outstanding, ending balance (in shares) 155,229,024 150,874,552 150,834,397 147,304,538 144,484,650 143,155,761 155,229,024 147,304,538
Shareholders' equity, ending balance $ 776 $ 754 $ 754 $ 737 $ 722 $ 716 $ 776 $ 737
Additional Paid-in Capital                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Shareholders' equity, beginning balance 6,953,761 6,945,795 6,684,120 6,213,523 6,065,763 5,838,118 6,684,120 5,838,118
Public and other stock offerings 499,562 4,025 257,757 315,682 143,808 223,768    
Stock-based compensation plans 10,011 3,941 3,918 8,615 3,952 3,877    
Shareholders' equity, ending balance 7,463,334 6,953,761 6,945,795 6,537,820 6,213,523 6,065,763 7,463,334 6,537,820
Accumulated Other Comprehensive Income (Loss)                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Shareholders' equity, beginning balance 495,700 468,592 518,528 360,997 391,330 369,112 518,528 369,112
Other comprehensive income (loss) 14,432 27,108 (49,936) 43,406 (30,333) 22,218    
Shareholders' equity, ending balance 510,132 495,700 468,592 404,403 360,997 391,330 510,132 404,403
Retained Earnings                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Shareholders' equity, beginning balance 4,168,424 3,858,068 3,666,674 3,629,963 3,378,465 3,211,157 3,666,674 3,211,157
Net income 165,564 432,023 311,292 137,807 357,671 271,860    
Cash dividends (125,154) (121,667) (119,898) (108,349) (106,173) (104,552)    
Shareholders' equity, ending balance $ 4,208,834 $ 4,168,424 $ 3,858,068 $ 3,659,421 $ 3,629,963 $ 3,378,465 $ 4,208,834 $ 3,659,421
v3.24.2.u1
Shareholders' Equity - Narrative (Details) - USD ($)
 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Class of Stock [Line Items]    
Forward sales equity agreement, settlement in cash $ 550,735,000  
Net proceeds from equity issuances 749,987,000 $ 671,630,000
Shelf Registration Statement    
Class of Stock [Line Items]    
Debt and equity securities authorized for issuance 5,000,000,000.0  
Debt and equity securities authorized for issuance value remaining 1,800,000,000  
At-The-Market    
Class of Stock [Line Items]    
Value of shares authorized for issuance $ 1,000,000,000  
Forward sales equity agreement (in shares) 7,224,450  
Forward sales equity agreement, settlement in cash $ 833,200,000  
Shares issued (in shares) 6,401,469  
Net proceeds from equity issuances $ 750,000,000.0  
Equity available for issuance $ 845,700,000  
v3.24.2.u1
Shareholders' Equity - Schedule of Forward Sales Agreement (Details)
$ / shares in Units, $ in Thousands
 9 Months Ended
Jun. 30, 2024
USD ($)
$ / shares
shares
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 4,784,006
Net proceeds available | $ $ 550,735
Forward price (USD per share) | $ / shares $ 115.12
Forward Sales Equity Agreement Maturing Quarter Ended June 30, 2025  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 3,931,418
Net proceeds available | $ $ 450,884
Forward price (USD per share) | $ / shares $ 114.69
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 | $ $ 95,523
Forward price (USD per share) | $ / shares $ 117.11
Forward Sales Equity Agreement Maturing Quarter Ended December 31, 2025  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 36,933
Net proceeds available | $ $ 4,328
Forward price (USD per share) | $ / shares $ 117.18
v3.24.2.u1
Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Jun. 30, 2023
Mar. 31, 2023
Dec. 31, 2022
Jun. 30, 2024
Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance $ 11,618,639 $ 11,273,209 $ 10,870,064 $ 10,205,205 $ 9,836,274 $ 9,419,091 $ 10,870,064 $ 9,419,091
Other comprehensive income (loss) before reclassifications             (923) 36,881
Amounts reclassified from accumulated other comprehensive income             (7,473) (1,590)
Total other comprehensive income (loss) 14,432 27,108 (49,936) 43,406 (30,333) 22,218 (8,396) 35,291
Shareholders' equity, ending balance 12,183,076 11,618,639 11,273,209 10,602,381 10,205,205 9,836,274 12,183,076 10,602,381
Available- for-Sale Securities                
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance     (369)     (495) (369) (495)
Other comprehensive income (loss) before reclassifications             242 100
Amounts reclassified from accumulated other comprehensive income             0 0
Total other comprehensive income (loss)             242 100
Shareholders' equity, ending balance (127)     (395)     (127) (395)
Interest Rate Agreement Cash Flow Hedges                
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance     518,897     369,607 518,897 369,607
Other comprehensive income (loss) before reclassifications             (1,165) 36,781
Amounts reclassified from accumulated other comprehensive income             (7,473) (1,590)
Total other comprehensive income (loss)             (8,638) 35,191
Shareholders' equity, ending balance 510,259     404,798     510,259 404,798
Accumulated Other Comprehensive Income (Loss)                
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance 495,700 468,592 518,528 360,997 391,330 369,112 518,528 369,112
Total other comprehensive income (loss) 14,432 27,108 (49,936) 43,406 (30,333) 22,218    
Shareholders' equity, ending balance $ 510,132 $ 495,700 $ 468,592 $ 404,403 $ 360,997 $ 391,330 $ 510,132 $ 404,403
v3.24.2.u1
Variable Interest Entity - Narrative (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Jun. 30, 2023
Variable Interest Entity [Line Items]      
Long-term debt, fair value $ 6,892,431 $ 5,402,591  
Securitized Utility Tariff Bonds | Senior Notes | Variable Interest Entity, Primary Beneficiary      
Variable Interest Entity [Line Items]      
Debt face amount     $ 95,000
Long-term debt 89,300    
Long-term debt, fair value $ 89,200    
v3.24.2.u1
Variable Interest Entity - Schedule of Condensed Consolidated Balance Sheet (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents $ 4,642 $ 3,844
Other current assets 479,840 292,036
Securitized intangible asset, net 84,998 92,202
Current maturities of securitized long-term debt 8,001 9,922
Securitized long-term debt 81,261 85,078
Variable Interest Entity, Primary Beneficiary    
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents 4,642 3,844
Other current assets 14 11
Securitized intangible asset, net 84,998 92,202
Accrued interest 1,534 1,374
Current maturities of securitized long-term debt 8,001 9,922
Securitized long-term debt $ 81,261 $ 85,078
v3.24.2.u1
Variable Interest Entity - Schedule of Consolidated Statement of Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Variable Interest Entity [Line Items]        
Operating revenues $ 701,549 $ 662,733 $ 3,507,243 $ 3,687,715
Operation and maintenance expense (211,309) (195,049) (577,553) (574,781)
Amortization expense (166,827) (150,726) (496,522) (445,063)
Interest expense, net (41,160) (31,334) (148,477) (105,464)
Income before income taxes 199,005 $ 154,089 1,076,356 $ 862,380
Variable Interest Entity, Primary Beneficiary        
Variable Interest Entity [Line Items]        
Operating revenues 3,463   10,265  
Operation and maintenance expense (52)   (276)  
Amortization expense (2,292)   (6,561)  
Interest expense, net (1,119)   (3,428)  
Income before income taxes $ 0   $ 0  
v3.24.2.u1
Interim Pension and Other Postretirement Benefit Plan Information - Narrative (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Nov. 30, 2023
Nov. 29, 2023
Sep. 30, 2024
Jun. 30, 2024
Dec. 31, 2023
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Defined Benefit Plan Disclosure [Line Items]                
Discount rate 5.82% 6.17%            
Forecast                
Defined Benefit Plan Disclosure [Line Items]                
Decrease of costs from plan revaluation     $ 400          
Pension Benefits                
Defined Benefit Plan Disclosure [Line Items]                
Settlement charge       $ 0 $ 800 $ 1,030 $ 776 $ 1,030
v3.24.2.u1
Interim Pension and Other Postretirement Benefit Plan Information - Schedule of Components of Net Periodic Pension Cost (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Dec. 31, 2023
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Pension Benefits          
Defined Benefit Plan Disclosure [Line Items]          
Service cost $ 2,405   $ 2,915 $ 7,199 $ 8,731
Interest cost 7,430   7,265 22,356 21,915
Expected return on assets (7,202)   (7,278) (21,606) (21,835)
Amortization of prior service cost (credit) 0   (30) 0 (91)
Amortization of actuarial (gain) loss 97   178 313 506
Settlements 0 $ (800) (1,030) (776) (1,030)
Net periodic pension cost 2,730   4,080 9,038 10,256
Other Benefits          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 1,507   1,546 4,521 4,637
Interest cost 3,509   3,478 10,526 10,433
Expected return on assets (3,128)   (2,804) (9,383) (8,411)
Amortization of prior service cost (credit) (3,260)   (3,285) (9,780) (9,856)
Amortization of actuarial (gain) loss (2,718)   (1,863) (8,154) (5,589)
Settlements 0   0 0 0
Net periodic pension cost $ (4,090)   $ (2,928) $ (12,270) $ (8,786)
v3.24.2.u1
Commitments and Contingencies (Details)
 9 Months Ended
Jan. 27, 2024
fatality
incident
Jun. 30, 2024
$ / Mcf
MMcf
National Transportation Safety Board    
Long-term Purchase Commitment [Line Items]    
Number of fatalities under investigation | fatality 1  
National Transportation Safety Board | Jackson, Mississippi    
Long-term Purchase Commitment [Line Items]    
Number of incidents investigated that occurred during period | incident 2  
Supply Commitment    
Long-term Purchase Commitment [Line Items]    
Contract term   1 year
Purchase commitment volume   12,800
Supply Commitment | Weighted Average    
Long-term Purchase Commitment [Line Items]    
Fixed price contracts (USD per Mcf) | $ / Mcf   3.06
Supply Commitment | Short-term Contract with Customer    
Long-term Purchase Commitment [Line Items]    
Contract term   1 year
Purchase commitment volume   67,800
Supply Commitment | Long-term Contract with Customer Within Two To Three Years    
Long-term Purchase Commitment [Line Items]    
Purchase commitment volume   31,500
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
v3.24.2.u1
Income Taxes (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Sep. 30, 2023
Income Tax Contingency [Line Items]          
Effective income tax rate 16.80% 10.60% 15.60% 11.00%  
Regulatory liabilities $ 1,187,372   $ 1,187,372   $ 1,284,334
Regulatory excess deferred taxes          
Income Tax Contingency [Line Items]          
Deferred tax liabilities, net 232,600   232,600    
Regulatory liabilities 283,073   283,073   384,513
Regulatory excess deferred taxes | Other Current Liabilities          
Income Tax Contingency [Line Items]          
Deferred tax liabilities, net 87,600   87,600   $ 131,300
Regulatory excess deferred taxes, to be returned, tranche one          
Income Tax Contingency [Line Items]          
Deferred tax liabilities, net 180,000   $ 180,000    
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 51,600   $ 51,600    
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     69 years    
Regulatory excess deferred taxes, to be returned, tranche three          
Income Tax Contingency [Line Items]          
Deferred tax liabilities, net $ 1,000   $ 1,000    
v3.24.2.u1
Financial Instruments - Narrative (Details)
 3 Months Ended 9 Months Ended
Jun. 30, 2024
USD ($)
Jun. 30, 2023
USD ($)
Jun. 30, 2024
USD ($)
MMcf
Jun. 30, 2023
USD ($)
Sep. 30, 2023
USD ($)
Derivative [Line Items]          
Purchase commitment volume | MMcf     15,455    
Contract netting $ 0   $ 0   $ 0
Cash collateral 0   0   $ 0
Net (gain) loss on settled interest rate agreements (3,200,000) $ (700,000) (9,600,000) $ (2,100,000)  
Net realized gains in AOCI $ 217,300,000   $ 217,300,000    
Not Designated as Hedging Instrument | Gas Purchases | Commodity contracts          
Derivative [Line Items]          
Purchase commitment volume | MMcf     27,600    
Not Designated as Hedging Instrument | Gas Purchases | Commodity contracts | Minimum          
Derivative [Line Items]          
Hedging percent 25.00%   25.00%    
Not Designated as Hedging Instrument | Gas Purchases | Commodity contracts | Maximum          
Derivative [Line Items]          
Hedging percent 50.00%   50.00%    
v3.24.2.u1
Financial Instruments - Schedule of Interest Rate Risk Management Activities (Details) - Cash Flow Hedging - Designated As Hedge
$ in Thousands
Jun. 30, 2024
USD ($)
Forward Interest Rate Swap  
Derivative [Line Items]  
Derivative notional amount $ 900,000
Forward Interest Rate Swap, Planned Issued Fiscal 2025  
Derivative [Line Items]  
Derivative notional amount 600,000
Forward Interest Rate Swap, Planned Issued Fiscal 2026  
Derivative [Line Items]  
Derivative notional amount $ 300,000
v3.24.2.u1
Financial Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets $ 381,220 $ 385,664
Gross/net financial instruments, liabilities (5,977) (15,408)
Designated As Hedges:    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 377,600 379,101
Gross/net financial instruments, liabilities 0 0
Designated As Hedges: | Other current assets | Interest rate contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 273,551  
Designated As Hedges: | Other current liabilities | Interest rate contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities 0  
Designated As Hedges: | Deferred charges and other assets | Interest rate contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 104,049 379,101
Designated As Hedges: | Deferred credits and other liabilities | Interest rate contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities 0 0
Not Designated As Hedges:    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 3,620 6,563
Gross/net financial instruments, liabilities (5,977) (15,408)
Not Designated As Hedges: | Other current assets | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 2,349 4,071
Not Designated As Hedges: | Other current liabilities | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities (5,928) (14,584)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 1,271 2,492
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities $ (49) $ (824)
v3.24.2.u1
Financial Instruments - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Increase (decrease) in fair value:        
Interest rate agreements $ 16,926 $ 44,057 $ (1,165) $ 36,781
Recognition of (gains) losses in earnings due to settlements:        
Interest rate agreements (2,490) (530) (7,473) (1,590)
Total other comprehensive income (loss) from hedging, net of tax $ 14,436 $ 43,527 $ (8,638) $ 35,191
v3.24.2.u1
Financial Instruments - Schedule Of Expected Deferred Gains (Losses) Recognition (Details)
$ in Thousands
 9 Months Ended
Jun. 30, 2024
USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Next twelve months $ 9,965
Thereafter 207,359
Total $ 217,324
v3.24.2.u1
Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments net assets $ 381,220 $ 385,664
Debt and equity securities 108,361 104,602
Total assets 489,581 490,266
Financial instruments net liability 5,977 15,408
Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 26,948 26,685
Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 39,253 37,573
Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Debt securities 38,369 35,507
Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 3,791 4,837
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 66,201 64,258
Total assets 66,201 64,258
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 26,948 26,685
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 39,253 37,573
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 381,220 385,664
Debt and equity securities 42,160 40,344
Total assets 423,380 426,008
Financial instruments gross liability 5,977 15,408
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 38,369 35,507
Significant Other Observable Inputs (Level 2) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 3,791 4,837
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
v3.24.2.u1
Fair Value Measurements - Narrative (Details) - USD ($)
Jun. 30, 2024
Sep. 30, 2023
Fair Value Disclosures [Abstract]    
Allowance for credit losses $ 0  
Cost basis $ 38,500,000 $ 36,000,000.0
v3.24.2.u1
Fair Value Measurements - Schedule of Debt Instruments (Details) - USD ($)
$ in Thousands
Jun. 30, 2024
Sep. 30, 2023
Fair Value Disclosures [Abstract]    
Carrying Amount $ 7,785,000 $ 6,560,000
Fair Value $ 6,892,431 $ 5,402,591