Atmos Energy (ATO) 10-Q 7 Aug 24 2024 Q3 Quarterly report Financial data

Cover Page

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

CONDENSED CONSOLIDATED BALANCE

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

CONDENSED CONSOLIDATED BALANC_2

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

CONDENSED CONSOLIDATED STATEMEN

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	$ 5.33
Diluted net income per share (USD per share)	1.08	0.94	6	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)

CONDENSED CONSOLIDATED STATEM_2

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

CONDENSED CONSOLIDATED STATEM_3

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

Nature of Business

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.

Summary of Significant Accounti

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.

Regulation

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, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 14,033 $ 20,629 Infrastructure mechanisms (1) 209,609 229,996 Winter Storm Uri incremental costs 12,549 32,115 Deferred gas costs 68,296 148,297 Regulatory excess deferred taxes (2) 50,462 47,549 Recoverable loss on reacquired debt 3,112 3,238 Deferred pipeline record collection costs 42,454 54,008 APT annual System Safety and Integrity Rider 35,721 — Other 15,288 19,096 $ 451,524 $ 554,928 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 283,073 $ 384,513 Regulatory cost of removal obligation 605,449 582,867 Deferred gas costs 20,188 23,093 APT annual adjustment mechanism 48,544 49,894 Pension and postretirement benefit costs 199,838 215,913 Other 30,280 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.

Segment Information

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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 632,446 $ 69,103 $ — $ 701,549 Intersegment revenues 765 181,577 (182,342) — Total operating revenues 633,211 250,680 (182,342) 701,549 Purchased gas cost 179,510 (19) (182,084) (2,593) Operation and maintenance expense 153,140 58,427 (258) 211,309 Depreciation and amortization expense 122,912 43,915 — 166,827 Taxes, other than income 94,527 11,212 — 105,739 Operating income 83,122 137,145 — 220,267 Other non-operating income 11,452 8,446 — 19,898 Interest charges 22,550 18,610 — 41,160 Income before income taxes 72,024 126,981 — 199,005 Income tax expense 6,175 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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 615,259 $ 47,474 $ — $ 662,733 Intersegment revenues 808 160,751 (161,559) — Total operating revenues 616,067 208,225 (161,559) 662,733 Purchased gas cost 206,048 (194) (161,304) 44,550 Operation and maintenance expense 138,351 56,953 (255) 195,049 Depreciation and amortization expense 107,809 42,917 — 150,726 Taxes, other than income 92,180 10,975 — 103,155 Operating income 71,679 97,574 — 169,253 Other non-operating income 6,695 9,475 — 16,170 Interest charges 16,146 15,188 — 31,334 Income before income taxes 62,228 91,861 — 154,089 Income tax expense 2,589 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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,325,459 $ 181,784 $ — $ 3,507,243 Intersegment revenues 2,271 503,552 (505,823) — Total operating revenues 3,327,730 685,336 (505,823) 3,507,243 Purchased gas cost 1,464,815 825 (505,069) 960,571 Operation and maintenance expense 435,711 142,596 (754) 577,553 Depreciation and amortization expense 363,981 132,541 — 496,522 Taxes, other than income 273,430 28,805 — 302,235 Operating income 789,793 380,569 — 1,170,362 Other non-operating income 26,650 27,821 — 54,471 Interest charges 93,915 54,562 — 148,477 Income before income taxes 722,528 353,828 — 1,076,356 Income tax expense 92,550 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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,554,389 $ 133,326 $ — $ 3,687,715 Intersegment revenues 2,314 445,952 (448,266) — Total operating revenues 3,556,703 579,278 (448,266) 3,687,715 Purchased gas cost 1,896,986 (431) (447,545) 1,449,010 Operation and maintenance expense 426,173 149,329 (721) 574,781 Depreciation and amortization expense 319,783 125,280 — 445,063 Taxes, other than income 275,002 30,782 — 305,784 Operating income 638,759 274,318 — 913,077 Other non-operating income 20,934 33,833 — 54,767 Interest charges 60,405 45,059 — 105,464 Income before income taxes 599,288 263,092 — 862,380 Income tax expense 56,707 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 Distribution Pipeline and Storage Eliminations Consolidated (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 Distribution Pipeline and Storage Eliminations Consolidated (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

Earnings Per Share

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 30 Nine Months Ended June 30 2024 2023 2024 2023 (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 shares 87 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

Revenue and Accounts Receivable

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, 2024 Three Months Ended June 30, 2023 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 384,957 $ — $ 380,099 $ — Commercial 169,508 — 165,930 — Industrial 21,160 — 23,533 — Public authority and other 8,177 — 8,562 — Total gas sales revenues 583,802 — 578,124 — Transportation revenues 30,773 260,779 27,988 212,322 Miscellaneous revenues 2,681 7,592 2,706 4,397 Revenues from contracts with customers 617,256 268,371 608,818 216,719 Alternative revenue program revenues 11,997 (17,691) 6,772 (8,494) Other revenues 3,958 — 477 — Total operating revenues $ 633,211 $ 250,680 $ 616,067 $ 208,225 Nine Months Ended June 30, 2024 Nine Months Ended June 30, 2023 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 2,177,935 $ — $ 2,276,240 $ — Commercial 851,462 — 953,409 — Industrial 79,810 — 127,792 — Public authority and other 43,881 — 54,074 — Total gas sales revenues 3,153,088 — 3,411,515 — Transportation revenues 102,147 699,243 93,661 597,822 Miscellaneous revenues 9,048 12,796 7,650 8,271 Revenues from contracts with customers 3,264,283 712,039 3,512,826 606,093 Alternative revenue program revenues 51,713 (26,703) 42,360 (26,815) Other revenues 11,734 — 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 provisions 3,575 Write-offs charged against allowance (4,407) Recoveries of amounts previously written off 286 Ending balance, June 30, 2024 $ 42,159 Three Months Ended June 30, 2023 (In thousands) Beginning balance, March 31, 2023 $ 52,751 Current period provisions 1,758 Write-offs charged against allowance (5,902) Recoveries of amounts previously written off 294 Ending balance, June 30, 2023 $ 48,901 Nine Months Ended June 30, 2024 (In thousands) Beginning balance, September 30, 2023 $ 40,840 Current period provisions 23,122 Write-offs charged against allowance (19,023) Recoveries of amounts previously written off 1,412 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 provisions 22,000 Write-offs charged against allowance (24,656) Recoveries of amounts previously written off 1,564 Ending balance, June 30, 2023 $ 48,901

Debt

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, 2024 September 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 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 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.

Shareholders' Equity

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 stock Additional Accumulated Retained Total Number of Stated (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 offerings 2,177,864 11 257,757 — — 257,768 Stock-based compensation plans 163,750 1 3,918 — — 3,919 Balance, December 31, 2023 150,834,397 754 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 offerings 34,687 — 4,025 — — 4,025 Stock-based compensation plans 5,468 — 3,941 — — 3,941 Balance, March 31, 2024 150,874,552 754 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 offerings 4,288,217 22 499,562 — — 499,584 Stock-based compensation plans 66,255 — 10,011 — — 10,011 Balance, June 30, 2024 155,229,024 $ 776 $ 7,463,334 $ 510,132 $ 4,208,834 $ 12,183,076 Common stock Additional Accumulated Retained Total Number of Stated (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 offerings 2,147,210 11 223,768 — — 223,779 Stock-based compensation plans 111,953 1 3,877 — — 3,878 Balance, December 31, 2022 143,155,761 716 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 offerings 1,316,930 6 143,808 — — 143,814 Stock-based compensation plans 11,959 — 3,952 — — 3,952 Balance, March 31, 2023 144,484,650 722 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 offerings 2,754,533 15 315,682 — — 315,697 Stock-based compensation plans 65,355 — 8,615 — — 8,615 Balance, June 30, 2023 147,304,538 $ 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. Maturity Shares Available Net Proceeds Available Forward Price June 30, 2025 3,931,418 $ 450,884 $ 114.69 September 30, 2025 815,655 95,523 $ 117.11 December 31, 2025 36,933 4,328 $ 117.18 Total 4,784,006 $ 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- Interest Rate Total (In thousands) September 30, 2023 $ (369) $ 518,897 $ 518,528 Other comprehensive income (loss) before reclassifications 242 (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- Interest Rate Total (In thousands) September 30, 2022 $ (495) $ 369,607 $ 369,112 Other comprehensive income before reclassifications 100 36,781 36,881 Amounts reclassified from accumulated other comprehensive income — (1,590) (1,590) Net current-period other comprehensive income 100 35,191 35,291 June 30, 2023 $ (395) $ 404,798 $ 404,403

Variable Interest Entity

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, 2024 September 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, 2024 Nine 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.

Interim Pension and Other Postr

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 Benefits Other Benefits 2024 2023 2024 2023 (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 Benefits Other Benefits 2024 2023 2024 2023 (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.

Commitments and Contingencies

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 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.

Income Taxes

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.

Financial Instruments

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 Date Amount Hedged (In thousands) Fiscal 2025 $ 600,000 Fiscal 2026 300,000 $ 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 Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Other current assets / $ 273,551 $ — Interest rate contracts Deferred charges and other assets / 104,049 — Total 377,600 — Not Designated As Hedges: Commodity contracts Other current assets / 2,349 (5,928) Commodity contracts Deferred charges and other assets / 1,271 (49) Total 3,620 (5,977) Gross / Net Financial Instruments $ 381,220 $ (5,977) September 30, 2023 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Deferred charges and other assets / $ 379,101 $ — Total 379,101 — Not Designated As Hedges: Commodity contracts Other current assets / 4,071 (14,584) Commodity contracts Deferred charges and other assets / 2,492 (824) Total 6,563 (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 30 Nine Months Ended June 30 2024 2023 2024 2023 (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 (In thousands) Next twelve months $ 9,965 Thereafter 207,359 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.

Fair Value Measurements

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 Significant Other Observable Inputs (Level 2) (1) Significant Netting and June 30, 2024 (In thousands) Assets: Financial instruments $ — $ 381,220 $ — $ — $ 381,220 Debt and equity securities Registered investment companies 26,948 — — — 26,948 Bond mutual funds 39,253 — — — 39,253 Bonds (2) — 38,369 — — 38,369 Money market funds — 3,791 — — 3,791 Total debt and equity securities 66,201 42,160 — — 108,361 Total assets $ 66,201 $ 423,380 $ — $ — $ 489,581 Liabilities: Financial instruments $ — $ 5,977 $ — $ — $ 5,977 Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and September 30, 2023 (In thousands) Assets: Financial instruments $ — $ 385,664 $ — $ — $ 385,664 Debt and equity securities Registered investment companies 26,685 — — — 26,685 Bond mutual funds 37,573 — — — 37,573 Bonds (2) — 35,507 — — 35,507 Money market funds — 4,837 — — 4,837 Total debt and equity securities 64,258 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, 2024 September 30, 2023 (In thousands) Carrying Amount $ 7,785,000 $ 6,560,000 Fair Value $ 6,892,431 $ 5,402,591

Concentration of Credit Risk

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.

Pay vs Performance Disclosure

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

Insider Trading Arrangements

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

Summary of Significant Accoun_2

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.

Regulation (Tables)

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, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 14,033 $ 20,629 Infrastructure mechanisms (1) 209,609 229,996 Winter Storm Uri incremental costs 12,549 32,115 Deferred gas costs 68,296 148,297 Regulatory excess deferred taxes (2) 50,462 47,549 Recoverable loss on reacquired debt 3,112 3,238 Deferred pipeline record collection costs 42,454 54,008 APT annual System Safety and Integrity Rider 35,721 — Other 15,288 19,096 $ 451,524 $ 554,928 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 283,073 $ 384,513 Regulatory cost of removal obligation 605,449 582,867 Deferred gas costs 20,188 23,093 APT annual adjustment mechanism 48,544 49,894 Pension and postretirement benefit costs 199,838 215,913 Other 30,280 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, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 14,033 $ 20,629 Infrastructure mechanisms (1) 209,609 229,996 Winter Storm Uri incremental costs 12,549 32,115 Deferred gas costs 68,296 148,297 Regulatory excess deferred taxes (2) 50,462 47,549 Recoverable loss on reacquired debt 3,112 3,238 Deferred pipeline record collection costs 42,454 54,008 APT annual System Safety and Integrity Rider 35,721 — Other 15,288 19,096 $ 451,524 $ 554,928 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 283,073 $ 384,513 Regulatory cost of removal obligation 605,449 582,867 Deferred gas costs 20,188 23,093 APT annual adjustment mechanism 48,544 49,894 Pension and postretirement benefit costs 199,838 215,913 Other 30,280 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.

Segment Information (Tables)

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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 632,446 $ 69,103 $ — $ 701,549 Intersegment revenues 765 181,577 (182,342) — Total operating revenues 633,211 250,680 (182,342) 701,549 Purchased gas cost 179,510 (19) (182,084) (2,593) Operation and maintenance expense 153,140 58,427 (258) 211,309 Depreciation and amortization expense 122,912 43,915 — 166,827 Taxes, other than income 94,527 11,212 — 105,739 Operating income 83,122 137,145 — 220,267 Other non-operating income 11,452 8,446 — 19,898 Interest charges 22,550 18,610 — 41,160 Income before income taxes 72,024 126,981 — 199,005 Income tax expense 6,175 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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 615,259 $ 47,474 $ — $ 662,733 Intersegment revenues 808 160,751 (161,559) — Total operating revenues 616,067 208,225 (161,559) 662,733 Purchased gas cost 206,048 (194) (161,304) 44,550 Operation and maintenance expense 138,351 56,953 (255) 195,049 Depreciation and amortization expense 107,809 42,917 — 150,726 Taxes, other than income 92,180 10,975 — 103,155 Operating income 71,679 97,574 — 169,253 Other non-operating income 6,695 9,475 — 16,170 Interest charges 16,146 15,188 — 31,334 Income before income taxes 62,228 91,861 — 154,089 Income tax expense 2,589 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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,325,459 $ 181,784 $ — $ 3,507,243 Intersegment revenues 2,271 503,552 (505,823) — Total operating revenues 3,327,730 685,336 (505,823) 3,507,243 Purchased gas cost 1,464,815 825 (505,069) 960,571 Operation and maintenance expense 435,711 142,596 (754) 577,553 Depreciation and amortization expense 363,981 132,541 — 496,522 Taxes, other than income 273,430 28,805 — 302,235 Operating income 789,793 380,569 — 1,170,362 Other non-operating income 26,650 27,821 — 54,471 Interest charges 93,915 54,562 — 148,477 Income before income taxes 722,528 353,828 — 1,076,356 Income tax expense 92,550 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 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 3,554,389 $ 133,326 $ — $ 3,687,715 Intersegment revenues 2,314 445,952 (448,266) — Total operating revenues 3,556,703 579,278 (448,266) 3,687,715 Purchased gas cost 1,896,986 (431) (447,545) 1,449,010 Operation and maintenance expense 426,173 149,329 (721) 574,781 Depreciation and amortization expense 319,783 125,280 — 445,063 Taxes, other than income 275,002 30,782 — 305,784 Operating income 638,759 274,318 — 913,077 Other non-operating income 20,934 33,833 — 54,767 Interest charges 60,405 45,059 — 105,464 Income before income taxes 599,288 263,092 — 862,380 Income tax expense 56,707 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 Distribution Pipeline and Storage Eliminations Consolidated (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 Distribution Pipeline and Storage Eliminations Consolidated (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

Earnings Per Share (Tables)

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 30 Nine Months Ended June 30 2024 2023 2024 2023 (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 shares 87 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

Revenue and Accounts Receivab_2

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, 2024 Three Months Ended June 30, 2023 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 384,957 $ — $ 380,099 $ — Commercial 169,508 — 165,930 — Industrial 21,160 — 23,533 — Public authority and other 8,177 — 8,562 — Total gas sales revenues 583,802 — 578,124 — Transportation revenues 30,773 260,779 27,988 212,322 Miscellaneous revenues 2,681 7,592 2,706 4,397 Revenues from contracts with customers 617,256 268,371 608,818 216,719 Alternative revenue program revenues 11,997 (17,691) 6,772 (8,494) Other revenues 3,958 — 477 — Total operating revenues $ 633,211 $ 250,680 $ 616,067 $ 208,225 Nine Months Ended June 30, 2024 Nine Months Ended June 30, 2023 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 2,177,935 $ — $ 2,276,240 $ — Commercial 851,462 — 953,409 — Industrial 79,810 — 127,792 — Public authority and other 43,881 — 54,074 — Total gas sales revenues 3,153,088 — 3,411,515 — Transportation revenues 102,147 699,243 93,661 597,822 Miscellaneous revenues 9,048 12,796 7,650 8,271 Revenues from contracts with customers 3,264,283 712,039 3,512,826 606,093 Alternative revenue program revenues 51,713 (26,703) 42,360 (26,815) Other revenues 11,734 — 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 provisions 3,575 Write-offs charged against allowance (4,407) Recoveries of amounts previously written off 286 Ending balance, June 30, 2024 $ 42,159 Three Months Ended June 30, 2023 (In thousands) Beginning balance, March 31, 2023 $ 52,751 Current period provisions 1,758 Write-offs charged against allowance (5,902) Recoveries of amounts previously written off 294 Ending balance, June 30, 2023 $ 48,901 Nine Months Ended June 30, 2024 (In thousands) Beginning balance, September 30, 2023 $ 40,840 Current period provisions 23,122 Write-offs charged against allowance (19,023) Recoveries of amounts previously written off 1,412 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 provisions 22,000 Write-offs charged against allowance (24,656) Recoveries of amounts previously written off 1,564 Ending balance, June 30, 2023 $ 48,901

Debt (Tables)

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, 2024 September 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 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

Shareholders' Equity (Tables)

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 stock Additional Accumulated Retained Total Number of Stated (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 offerings 2,177,864 11 257,757 — — 257,768 Stock-based compensation plans 163,750 1 3,918 — — 3,919 Balance, December 31, 2023 150,834,397 754 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 offerings 34,687 — 4,025 — — 4,025 Stock-based compensation plans 5,468 — 3,941 — — 3,941 Balance, March 31, 2024 150,874,552 754 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 offerings 4,288,217 22 499,562 — — 499,584 Stock-based compensation plans 66,255 — 10,011 — — 10,011 Balance, June 30, 2024 155,229,024 $ 776 $ 7,463,334 $ 510,132 $ 4,208,834 $ 12,183,076 Common stock Additional Accumulated Retained Total Number of Stated (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 offerings 2,147,210 11 223,768 — — 223,779 Stock-based compensation plans 111,953 1 3,877 — — 3,878 Balance, December 31, 2022 143,155,761 716 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 offerings 1,316,930 6 143,808 — — 143,814 Stock-based compensation plans 11,959 — 3,952 — — 3,952 Balance, March 31, 2023 144,484,650 722 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 offerings 2,754,533 15 315,682 — — 315,697 Stock-based compensation plans 65,355 — 8,615 — — 8,615 Balance, June 30, 2023 147,304,538 $ 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. Maturity Shares Available Net Proceeds Available Forward Price June 30, 2025 3,931,418 $ 450,884 $ 114.69 September 30, 2025 815,655 95,523 $ 117.11 December 31, 2025 36,933 4,328 $ 117.18 Total 4,784,006 $ 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- Interest Rate Total (In thousands) September 30, 2023 $ (369) $ 518,897 $ 518,528 Other comprehensive income (loss) before reclassifications 242 (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- Interest Rate Total (In thousands) September 30, 2022 $ (495) $ 369,607 $ 369,112 Other comprehensive income before reclassifications 100 36,781 36,881 Amounts reclassified from accumulated other comprehensive income — (1,590) (1,590) Net current-period other comprehensive income 100 35,191 35,291 June 30, 2023 $ (395) $ 404,798 $ 404,403

Variable Interest Entity (Table

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, 2024 September 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, 2024 Nine 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.

Interim Pension and Other Pos_2

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 Benefits Other Benefits 2024 2023 2024 2023 (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 Benefits Other Benefits 2024 2023 2024 2023 (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.

Financial Instruments (Tables)

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 Date Amount Hedged (In thousands) Fiscal 2025 $ 600,000 Fiscal 2026 300,000 $ 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 Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Other current assets / $ 273,551 $ — Interest rate contracts Deferred charges and other assets / 104,049 — Total 377,600 — Not Designated As Hedges: Commodity contracts Other current assets / 2,349 (5,928) Commodity contracts Deferred charges and other assets / 1,271 (49) Total 3,620 (5,977) Gross / Net Financial Instruments $ 381,220 $ (5,977) September 30, 2023 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Deferred charges and other assets / $ 379,101 $ — Total 379,101 — Not Designated As Hedges: Commodity contracts Other current assets / 4,071 (14,584) Commodity contracts Deferred charges and other assets / 2,492 (824) Total 6,563 (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 30 Nine Months Ended June 30 2024 2023 2024 2023 (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 (In thousands) Next twelve months $ 9,965 Thereafter 207,359 Total $ 217,324

Fair Value Measurements (Tables

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 Significant Other Observable Inputs (Level 2) (1) Significant Netting and June 30, 2024 (In thousands) Assets: Financial instruments $ — $ 381,220 $ — $ — $ 381,220 Debt and equity securities Registered investment companies 26,948 — — — 26,948 Bond mutual funds 39,253 — — — 39,253 Bonds (2) — 38,369 — — 38,369 Money market funds — 3,791 — — 3,791 Total debt and equity securities 66,201 42,160 — — 108,361 Total assets $ 66,201 $ 423,380 $ — $ — $ 489,581 Liabilities: Financial instruments $ — $ 5,977 $ — $ — $ 5,977 Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and September 30, 2023 (In thousands) Assets: Financial instruments $ — $ 385,664 $ — $ — $ 385,664 Debt and equity securities Registered investment companies 26,685 — — — 26,685 Bond mutual funds 37,573 — — — 37,573 Bonds (2) — 35,507 — — 35,507 Money market funds — 4,837 — — 4,837 Total debt and equity securities 64,258 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, 2024 September 30, 2023 (In thousands) Carrying Amount $ 7,785,000 $ 6,560,000 Fair Value $ 6,892,431 $ 5,402,591

Nature of Business (Details)

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

Regulation - Schedule of Regula

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

Regulation - Narrative (Details

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
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

Segment Information - Narrative

Segment Information - Narrative (Details)	Jun. 30, 2024 state
Segment Reporting [Abstract]
Number of states with service areas	8

Segment Information - Schedule

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

Segment Information - Schedul_2

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)

Earnings Per Share (Details)

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	$ 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	$ 5.33

Revenue and Accounts Receivab_3

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

Revenue and Accounts Receivab_4

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%			88%
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%
Pipeline and storage segment
Disaggregation of Revenue [Line Items]
Rate case revenue benchmark	$ 69,400	$ 106,900

Revenue and Accounts Receivab_5

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

Debt - Schedule of Long-term De

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%
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

Debt - Narrative (Details)

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%
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%
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%
$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

Shareholders' Equity - Schedule

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

Shareholders' Equity - Narrativ

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
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
Equity available for issuance	$ 845,700,000

Shareholders' Equity - Schedu_2

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

Shareholders' Equity - Schedu_3

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

Variable Interest Entity - Narr

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

Variable Interest Entity - Sche

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

Variable Interest Entity - Sc_2

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

Interim Pension and Other Pos_3

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

Interim Pension and Other Pos_4

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)

Commitments and Contingencies (

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

Income Taxes (Details)

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%
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

Financial Instruments - Narrati

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%		25%
Not Designated as Hedging Instrument | Gas Purchases | Commodity contracts | Maximum
Derivative [Line Items]
Hedging percent	50%		50%

Financial Instruments - Schedul

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

Financial Instruments - Sched_2

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)

Financial Instruments - Sched_3

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

Financial Instruments - Sched_4

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

Fair Value Measurements - Sched

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

Fair Value Measurements - Narra

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

Fair Value Measurements - Sch_2

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