Atmos Energy (ATO) 10-Q 6 Feb 24 2024 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Dec. 31, 2023	Feb. 02, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2023
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)		150,839,709
Entity Central Index Key	0000731802
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
ASSETS
Property, plant and equipment	$ 23,683,937	$ 22,898,374
Less accumulated depreciation and amortization	3,364,456	3,291,791
Net property, plant and equipment	20,319,481	19,606,583
Current assets
Cash and cash equivalents	278,315	15,404
Restricted cash and cash equivalents	7,130	3,844
Cash and cash equivalents and restricted cash and cash equivalents	285,445	19,248
Accounts receivable, net (See Note 6)	646,401	328,654
Gas stored underground	220,944	245,830
Other current assets	526,927	292,036
Total current assets	1,679,717	885,768
Securitized intangible asset, net (See Note 9)	90,036	92,202
Goodwill	731,257	731,257
Deferred charges and other assets	863,752	1,201,158
Total assets	23,684,243	22,516,968
Shareholders’ equity
Common stock, no par value (stated at $0.005 per share); 200,000,000 shares authorized; issued and outstanding: December 31, 2023 — 150,834,397 shares; September 30, 2023 — 148,492,783 shares	754	742
Additional paid-in capital	6,945,795	6,684,120
Accumulated other comprehensive income	468,592	518,528
Retained earnings	3,858,068	3,666,674
Shareholders’ equity	11,273,209	10,870,064
Long-term debt, net	7,444,195	6,554,133
Securitized long-term debt (See Note 9)	85,078	85,078
Total capitalization	18,802,482	17,509,275
Current liabilities
Accounts payable and accrued liabilities	416,694	336,083
Other current liabilities	742,304	763,086
Short-term debt	0	241,933
Current maturities of long-term debt	1,561	1,568
Current maturities of securitized long-term debt (See Note 9)	9,922	9,922
Total current liabilities	1,170,481	1,352,592
Deferred income taxes	2,379,421	2,304,974
Regulatory excess deferred taxes	231,981	253,212
Regulatory cost of removal obligation	498,135	497,017
Deferred credits and other liabilities	601,743	599,898
Total capitalization and liabilities	$ 23,684,243	$ 22,516,968

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	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)	150,834,397	148,492,783
Common stock outstanding (in shares)	150,834,397	148,492,783

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating revenues	$ 1,158,467	$ 1,484,009
Purchased gas cost	338,869	738,249
Operation and maintenance expense	166,345	185,016
Depreciation and amortization expense	164,608	146,020
Taxes, other than income	89,540	93,538
Operating income	399,105	321,186
Other non-operating income	17,886	21,191
Interest charges	51,875	36,760
Income before income taxes	365,116	305,617
Income tax expense	53,824	33,757
Net income	$ 311,292	$ 271,860
Basic net income per share (USD per share)	$ 2.08	$ 1.92
Diluted net income per share (USD per share)	2.08	1.91
Cash dividends per share (USD per share)	$ 0.805	$ 0.740
Basic weighted average shares outstanding (in shares)	149,796	141,820
Diluted weighted average shares outstanding (in shares)	149,796	141,937
Other comprehensive income (loss), net of tax
Net unrealized holding gains on available-for-sale securities, net of tax of $86 and $25	$ 296	$ 87
Cash flow hedges:
Amortization and unrealized gains (losses) on interest rate agreements, net of tax of $(14,519) and $6,397	(50,232)	22,131
Total other comprehensive income (loss)	(49,936)	22,218
Total comprehensive income	261,356	294,078
Purchased gas cost
Purchased gas cost	338,869	738,249
Distribution segment
Operating revenues	1,104,619	1,439,693
Pipeline and storage segment
Operating revenues	53,848	44,316
Operating Segments | Distribution segment
Operating revenues	1,105,338	1,440,426
Purchased gas cost	496,662	881,915
Operation and maintenance expense	127,615	136,469
Depreciation and amortization expense	119,685	105,664
Taxes, other than income	80,895	84,622
Operating income	280,481	231,756
Other non-operating income	5,839	6,774
Interest charges	34,581	22,839
Income before income taxes	251,739	215,691
Income tax expense	30,302	21,223
Net income	221,437	194,468
Operating Segments | Distribution segment | Purchased gas cost
Purchased gas cost	496,662	881,915
Operating Segments | Pipeline and storage segment
Operating revenues	211,169	186,629
Purchased gas cost	4	(858)
Operation and maintenance expense	38,973	48,785
Depreciation and amortization expense	44,923	40,356
Taxes, other than income	8,645	8,916
Operating income	118,624	89,430
Other non-operating income	12,047	14,417
Interest charges	17,294	13,921
Income before income taxes	113,377	89,926
Income tax expense	23,522	12,534
Net income	89,855	77,392
Operating Segments | Pipeline and storage segment | Purchased gas cost
Purchased gas cost	4	(858)
Intersegment eliminations
Operating revenues	(158,040)	(143,046)
Purchased gas cost	(157,797)	(142,808)
Operation and maintenance expense	(243)	(238)
Depreciation and amortization expense	0	0
Taxes, other than income	0	0
Operating income	0	0
Other non-operating income	0	0
Interest charges	0	0
Income before income taxes	0	0
Income tax expense	0	0
Net income	0	0
Intersegment eliminations | Purchased gas cost
Purchased gas cost	(157,797)	(142,808)
Intersegment eliminations | Distribution segment
Operating revenues	719	733
Intersegment eliminations | Pipeline and storage segment
Operating revenues	$ 157,321	$ 142,313

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Net unrealized holding gains on available-for-sale securities, tax	$ 86	$ 25
Amortization and unrealized gains (losses) on interest rate agreements, tax	$ (14,519)	$ 6,397

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash Flows From Operating Activities
Net income	$ 311,292	$ 271,860
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	164,608	146,020
Deferred income taxes	44,108	29,693
Other	(16,839)	(17,508)
Net assets / liabilities from risk management activities	5,589	218
Net change in other operating assets and liabilities	(263,478)	(241,383)
Net cash provided by operating activities	245,280	188,900
Cash Flows From Investing Activities
Capital expenditures	(769,650)	(795,660)
Debt and equity securities activities, net	(78)	(2,472)
Other, net	5,353	5,621
Net cash used in investing activities	(764,375)	(792,511)
Cash Flows From Financing Activities
Net decrease in short-term debt	(241,933)	(184,967)
Net proceeds from equity issuances	254,022	220,000
Issuance of common stock through stock purchase and employee retirement plans	3,746	3,779
Proceeds from issuance of long-term debt	898,275	797,258
Cash dividends paid	(119,898)	(104,552)
Debt issuance costs	(8,920)	(7,864)
Net cash provided by financing activities	785,292	723,654
Net increase in cash and cash equivalents and restricted cash and cash equivalents	266,197	120,043
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	$ 285,445	$ 171,597

Nature of Business

Nature of Business	3 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Atmos Energy Corporation (“Atmos Energy” or the “Company”) and its subsidiaries are engaged in the regulated natural gas distribution and pipeline and storage businesses. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our regulated divisions and subsidiaries operate. Our distribution business delivers natural gas through sales and transportation arrangements to over 3.3 million residential, commercial, public authority and industrial customers through our six regulated distribution divisions, which at December 31, 2023, 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	3 Months Ended
	Dec. 31, 2023
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 three-month period ended December 31, 2023 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. Except as described in Note 11 to the condensed consolidated financial statements, 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	3 Months Ended
	Dec. 31, 2023
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. Significant regulatory assets and liabilities as of December 31, 2023 and September 30, 2023 included the following: December 31, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 18,295 $ 20,629 Infrastructure mechanisms (1) 167,965 229,996 Winter Storm Uri incremental costs 28,328 32,115 Deferred gas costs 129,891 148,297 Regulatory excess deferred taxes (2) 47,772 47,549 Recoverable loss on reacquired debt 3,196 3,238 Deferred pipeline record collection costs 59,830 54,008 Other 16,518 19,096 $ 471,795 $ 554,928 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 343,075 $ 384,513 Regulatory cost of removal obligation 584,640 582,867 Deferred gas costs 20,889 23,093 APT annual adjustment mechanism 47,768 49,894 Pension and postretirement benefit costs 211,600 215,913 Other 28,777 28,054 $ 1,236,749 $ 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 $17.4 million and $21.2 million as a current asset in other current assets as of December 31, 2023 and September 30, 2023. We anticipate recovering the remaining $10.9 million in future regulatory filings and have recorded this amount as a long-term asset in deferred charges and other assets as of December 31, 2023.

Segment Information

Segment Information	3 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Segment Information	Segment Information We manage and review our consolidated operations through the following reportable segments: • The distribution segment is primarily comprised of our regulated natural gas distribution and related sales operations in eight states. • The pipeline and storage segment is comprised primarily of the 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 months ended December 31, 2023 and 2022 by segment are presented in the following tables: Three Months Ended December 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,104,619 $ 53,848 $ — $ 1,158,467 Intersegment revenues 719 157,321 (158,040) — Total operating revenues 1,105,338 211,169 (158,040) 1,158,467 Purchased gas cost 496,662 4 (157,797) 338,869 Operation and maintenance expense 127,615 38,973 (243) 166,345 Depreciation and amortization expense 119,685 44,923 — 164,608 Taxes, other than income 80,895 8,645 — 89,540 Operating income 280,481 118,624 — 399,105 Other non-operating income 5,839 12,047 — 17,886 Interest charges 34,581 17,294 — 51,875 Income before income taxes 251,739 113,377 — 365,116 Income tax expense 30,302 23,522 — 53,824 Net income $ 221,437 $ 89,855 $ — $ 311,292 Capital expenditures $ 539,158 $ 230,492 $ — $ 769,650 Three Months Ended December 31, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,439,693 $ 44,316 $ — $ 1,484,009 Intersegment revenues 733 142,313 (143,046) — Total operating revenues 1,440,426 186,629 (143,046) 1,484,009 Purchased gas cost 881,915 (858) (142,808) 738,249 Operation and maintenance expense 136,469 48,785 (238) 185,016 Depreciation and amortization expense 105,664 40,356 — 146,020 Taxes, other than income 84,622 8,916 — 93,538 Operating income 231,756 89,430 — 321,186 Other non-operating income 6,774 14,417 — 21,191 Interest charges 22,839 13,921 — 36,760 Income before income taxes 215,691 89,926 — 305,617 Income tax expense 21,223 12,534 — 33,757 Net income $ 194,468 $ 77,392 $ — $ 271,860 Capital expenditures $ 443,544 $ 352,116 $ — $ 795,660 Balance sheet information at December 31, 2023 and September 30, 2023 by segment is presented in the following tables: December 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Net property, plant and equipment $ 14,907,406 $ 5,412,075 $ — $ 20,319,481 Total assets $ 22,874,926 $ 5,721,542 $ (4,912,225) $ 23,684,243 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	3 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock. Additionally, the weighted average shares outstanding for diluted EPS includes the incremental effects of the forward sale agreements, discussed in Note 8 to the condensed consolidated financial statements, when the impact is dilutive. Basic and diluted earnings per share for the three months ended December 31, 2023 and 2022 are calculated as follows: Three Months Ended December 31 2023 2022 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 311,292 $ 271,860 Less: Income allocated to participating securities 186 167 Income available to common shareholders $ 311,106 $ 271,693 Basic weighted average shares outstanding 149,796 141,820 Net income per share — Basic $ 2.08 $ 1.92 Diluted Earnings Per Share Income available to common shareholders $ 311,106 $ 271,693 Effect of dilutive shares — — Income available to common shareholders $ 311,106 $ 271,693 Basic weighted average shares outstanding 149,796 141,820 Dilutive shares — 117 Diluted weighted average shares outstanding 149,796 141,937 Net income per share — Diluted $ 2.08 $ 1.91

Revenue and Accounts Receivable

Revenue and Accounts Receivable	3 Months Ended
	Dec. 31, 2023
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 months ended December 31, 2023 and 2022. Three Months Ended December 31, 2023 Three Months Ended December 31, 2022 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 727,682 $ — $ 953,051 $ — Commercial 277,253 — 388,667 — Industrial 28,231 — 59,215 — Public authority and other 14,584 — 22,826 — Total gas sales revenues 1,047,750 — 1,423,759 — Transportation revenues 33,767 215,305 32,162 195,252 Miscellaneous revenues 2,643 3,042 2,282 2,722 Revenues from contracts with customers 1,084,160 218,347 1,458,203 197,974 Alternative revenue program revenues 17,401 (7,178) (18,322) (11,345) Other revenues 3,777 — 545 — Total operating revenues $ 1,105,338 $ 211,169 $ 1,440,426 $ 186,629 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 three months ended December 31, 2023, there were no material changes to this policy. Rollforwards of our allowance for uncollectible accounts for the three months ended December 31, 2023 and 2022 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 December 31, 2023 (In thousands) Beginning balance, September 30, 2023 $ 40,840 Current period provisions 6,750 Write-offs charged against allowance (8,757) Recoveries of amounts previously written off 765 Mississippi recovery of uncollectible accounts (4,192) Ending balance, December 31, 2023 $ 35,406 Three Months Ended December 31, 2022 (In thousands) Beginning balance, September 30, 2022 $ 49,993 Current period provisions 7,233 Write-offs charged against allowance (10,421) Recoveries of amounts previously written off 808 Ending balance, December 31, 2022 $ 47,613

Debt

Debt	3 Months Ended
	Dec. 31, 2023
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 three months ended December 31, 2023. Long-term debt at December 31, 2023 and September 30, 2023 consisted of the following: December 31, 2023 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 400,000 — 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 50,052 50,393 Total long-term debt 7,510,052 6,610,393 Less: Original issue discount on unsecured senior notes and debentures 7,723 6,104 Debt issuance cost 56,573 48,588 Current maturities of long-term debt 1,561 1,568 Total long-term debt, net $ 7,444,195 $ 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. 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 $2.5 billion of total working capital funding. Our commercial paper program is supported by a five-year unsecured $1.5 billion credit facility that expires on March 31, 2027. This facility bears interest at a base rate or at a 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 SOFR-based advances, based on the Company’s credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the total committed loan to $1.75 billion. At December 31, 2023, 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 have a $900 million three-year unsecured revolving credit facility, which expires March 31, 2025 and is used to provide additional working capital funding. This facility bears interest at a base rate or at a 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 SOFR-based advances, based on the Company's credit ratings. Additionally, the facility contains a $100 million accordion feature, which provides the opportunity to increase the total committed loan to $1.0 billion. At December 31, 2023 and September 30, 2023, there were no borrowings outstanding under this facility. Additionally, we have a $50 million 364-day unsecured facility, which will expire March 31, 2024 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of December 31, 2023 and September 30, 2023. Finally, we have a $50 million 364-day unsecured revolving credit facility, which will expire March 31, 2024 and is used to issue letters of credit and to provide working capital funding. At December 31, 2023, there were no borrowings outstanding under this facility; however, outstanding letters of credit reduced the total amount available to us to $44.4 million. Debt covenants The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total-debt-to-total-capitalization of no greater than 70 percent. At December 31, 2023, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 41 percent. In addition, both the interest margin and the fee that we pay on unused amounts under certain of these facilities are subject to adjustment depending upon our credit ratings. These credit facilities and our public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as certain of our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or if not paid at maturity. We were in compliance with all of our debt covenants as of December 31, 2023. 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	3 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Shareholders' Equity	Shareholders' Equity The following tables present a reconciliation of changes in stockholders' equity for the three months ended December 31, 2023 and 2022. 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 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 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 December 31, 2023, $3.1 billion of securities were available for issuance under this shelf registration statement. We have 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). During the three months ended December 31, 2023, we executed forward sales under our ATM equity sales program with various forward sellers who borrowed and sold 2,284,076 shares of our common stock at an aggregate price of $261.4 million. During the three months ended December 31, 2023, we also settled forward sale agreements with respect to 2,144,558 shares that had been borrowed and sold by various forward sellers under the ATM program for net proceeds of $254.0 million. As of December 31, 2023, $499.1 million of equity was available for issuance under our existing ATM program. Additionally, we had $473.5 million in available proceeds from outstanding forward sale agreements, as detailed below. Maturity Shares Available Net Proceeds Available Forward Price September 30, 2024 861,655 $ 101,376 $ 117.65 December 31, 2024 2,176,974 250,866 $ 115.24 June 30, 2025 1,061,914 121,230 $ 114.16 Total 4,100,543 $ 473,472 $ 115.47 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 296 (47,741) (47,445) Amounts reclassified from accumulated other comprehensive income — (2,491) (2,491) Net current-period other comprehensive income (loss) 296 (50,232) (49,936) December 31, 2023 $ (73) $ 468,665 $ 468,592 Available- Interest Rate Total (In thousands) September 30, 2022 $ (495) $ 369,607 $ 369,112 Other comprehensive income before reclassifications 87 22,661 22,748 Amounts reclassified from accumulated other comprehensive income — (530) (530) Net current-period other comprehensive income 87 22,131 22,218 December 31, 2022 $ (408) $ 391,738 $ 391,330

Variable Interest Entity

Variable Interest Entity	3 Months Ended
	Dec. 31, 2023
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: December 31, 2023 September 30, 2023 (In thousands) Restricted cash and cash equivalents $ 7,130 $ 3,844 Other current assets $ 23 $ 11 Securitized intangible asset, net $ 90,036 $ 92,202 Accrued interest $ 2,598 $ 1,374 Current maturities of securitized long-term debt $ 9,922 $ 9,922 Securitized long-term debt $ 85,078 $ 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 December 31, 2023 (In thousands) Operating revenues $ 3,333 Amortization expense (2,166) Interest expense, net (1,167) Income before income taxes $ — The securitized long-term debt is recorded at carrying value. The fair value of the securitized long-term debt is determined using third party market value quotations, which are considered Level 2 fair value measurements for debt instruments where fair value is determined using the most recent available quoted market price. The carrying value and fair value of the securitized long-term debt as of December 31, 2023 is $95.0 million and $96.2 million.

Interim Pension and Other Postr

Interim Pension and Other Postretirement Benefit Plan Information	3 Months Ended
	Dec. 31, 2023
Retirement Benefits, Description [Abstract]
Interim Pension and Other Postretirement Benefit Plan Information	Interim Pension and Other Postretirement Benefit Plan Information The components of our net periodic pension cost for our pension and other postretirement benefit plans for the three months ended December 31, 2023 and 2022 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 December 31 Pension Benefits Other Benefits 2023 2022 2023 2022 (In thousands) Components of net periodic pension cost: Service cost $ 2,389 $ 2,908 $ 1,507 $ 1,546 Interest cost (1) 7,497 7,325 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) 118 164 (2,718) (1,863) Settlements (1) 776 — — — Net periodic pension cost $ 3,578 $ 3,089 $ (4,090) $ (2,928) (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	3 Months Ended
	Dec. 31, 2023
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) is investigating an incident that occurred at a Jackson, Mississippi residence on January 24, 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 December 31, 2023, we were committed to purchase 71.8 Bcf within one year and 51.3 Bcf within two Rate Regulatory Proceedings As of December 31, 2023, routine rate regulatory proceedings were in progress in several of our service areas, which are discussed in further detail below in Management’s Discussion and Analysis — Recent Ratemaking Developments . Except for these proceedings, there were no material changes to rate regulatory proceedings for the three months ended December 31, 2023.

Income Taxes

Income Taxes	3 Months Ended
	Dec. 31, 2023
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 December 31, 2023 and 2022 were 14.7% 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 $295.3 million is being returned over various periods. Of this amount, $241.9 million is being returned to customers over 12 - 60 months. An additional $52.4 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 December 31, 2023 and September 30, 2023, $111.1 million and $131.3 million is recorded in other current liabilities.

Financial Instruments

Financial Instruments	3 Months Ended
	Dec. 31, 2023
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 three months ended December 31, 2023, 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 anticipate hedging approximately 30.2 Bcf, of the winter flowing gas requirements. We have not designated these financial instruments as hedges for accounting purposes. Interest Rate Risk Management Activities We manage interest rate risk by periodically entering into financial instruments to effectively fix the Treasury yield component of the interest cost associated with anticipated financings. The following table summarizes our existing forward starting interest rate swaps as of December 31, 2023. 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 December 31, 2023, our financial instruments were comprised of both long and short commodity positions. A long position is a contract to purchase the commodity, while a short position is a contract to sell the commodity. As of December 31, 2023, we had 20,045 MMcf of net long commodity contracts outstanding. These contracts have not been designated as hedges. Financial Instruments on the Balance Sheet The following tables present the fair value and balance sheet classification of our financial instruments as of December 31, 2023 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 December 31, 2023 and September 30, 2023, no gross amounts and no cash collateral were netted within our consolidated balance sheet. December 31, 2023 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Other current assets / $ 232,975 $ — Interest rate contracts Deferred charges and other assets / 84,586 — Total 317,561 — Not Designated As Hedges: Commodity contracts Other current assets / 2,545 (19,819) Commodity contracts Deferred charges and other assets / 761 (1,777) Total 3,306 (21,596) Gross / Net Financial Instruments $ 320,867 $ (21,596) 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 December 31, 2023 and 2022 was $(3.2) million and $(0.7) million. The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three months ended December 31, 2023 and 2022. Three Months Ended December 31 2023 2022 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (47,741) $ 22,661 Recognition of (gains) losses in earnings due to settlements: Interest rate agreements (2,491) (530) Total other comprehensive income (loss) from hedging, net of tax $ (50,232) $ 22,131 Deferred gains (losses) recorded in AOCI associated with our interest rate agreements are recognized in earnings as they are amortized over the terms of the underlying debt instruments. As of December 31, 2023, we had $222.3 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 212,342 Total $ 222,307 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	3 Months Ended
	Dec. 31, 2023
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 three months ended December 31, 2023, 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 December 31, 2023 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 December 31, 2023 (In thousands) Assets: Financial instruments $ — $ 320,867 $ — $ — $ 320,867 Debt and equity securities Registered investment companies 28,466 — — — 28,466 Bond mutual funds 38,584 — — — 38,584 Bonds (2) — 36,343 — — 36,343 Money market funds — 3,861 — — 3,861 Total debt and equity securities 67,050 40,204 — — 107,254 Total assets $ 67,050 $ 361,071 $ — $ — $ 428,121 Liabilities: Financial instruments $ — $ 21,596 $ — $ — $ 21,596 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 December 31, 2023, no allowance for credit losses was recorded for our available-for-sale debt securities. At December 31, 2023 and September 30, 2023, the amortized cost of our available-for-sale debt securities was $36.4 million and $36.0 million. At December 31, 2023, we maintained investments in bonds that have contractual maturity dates ranging from January 2024 through November 2026. Other Fair Value Measures Our long-term debt is recorded at carrying value. The fair value of our long-term debt, excluding finance leases, is determined using third party market value quotations, which are considered Level 1 fair value measurements for debt instruments with a recent, observable trade or Level 2 fair value measurements for debt instruments where fair value is determined using the most recent available quoted market price. The carrying value of our finance leases materially approximates fair value. The following table presents the carrying value and fair value of our long-term debt, excluding finance leases, debt issuance costs and original issue premium or discount, as of December 31, 2023 and September 30, 2023: December 31, 2023 September 30, 2023 (In thousands) Carrying Amount $ 7,460,000 $ 6,560,000 Fair Value $ 6,963,106 $ 5,402,591

Concentration of Credit Risk

Concentration of Credit Risk	3 Months Ended
	Dec. 31, 2023
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 three months ended December 31, 2023, 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
	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net income	$ 311,292	$ 271,860

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023 shares
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
Kim R. Cocklin [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On December 7, 2023, Kim R. Cocklin, Chairman of the Board of Directors of the Company, adopted a Rule 10b5-1 trading arrangement for the sale of 15,000 shares of the Company's common stock, subject to certain conditions. Mr. Cocklin's trading arrangement will terminate on the earlier of (i) December 16, 2024, (ii) the execution of all trades or expiration of all orders relating to such trades under the Rule 10b5-1 trading arrangement, or (iii) such date as the Rule 10b5-1 trading arrangement is otherwise terminated according to its terms.
Name	Kim R. Cocklin
Title	Chairman of the Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 7, 2023
Arrangement Duration	375 days
Aggregate Available	15,000

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Recently issued accounting pronouncements	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	Earnings Per ShareWe 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	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 three months ended December 31, 2023, there were no changes in these methods.

Regulation (Tables)

Regulation (Tables)	3 Months Ended
	Dec. 31, 2023
Regulated Operations [Abstract]
Schedule of Regulatory Assets	Significant regulatory assets and liabilities as of December 31, 2023 and September 30, 2023 included the following: December 31, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 18,295 $ 20,629 Infrastructure mechanisms (1) 167,965 229,996 Winter Storm Uri incremental costs 28,328 32,115 Deferred gas costs 129,891 148,297 Regulatory excess deferred taxes (2) 47,772 47,549 Recoverable loss on reacquired debt 3,196 3,238 Deferred pipeline record collection costs 59,830 54,008 Other 16,518 19,096 $ 471,795 $ 554,928 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 343,075 $ 384,513 Regulatory cost of removal obligation 584,640 582,867 Deferred gas costs 20,889 23,093 APT annual adjustment mechanism 47,768 49,894 Pension and postretirement benefit costs 211,600 215,913 Other 28,777 28,054 $ 1,236,749 $ 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	Significant regulatory assets and liabilities as of December 31, 2023 and September 30, 2023 included the following: December 31, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 18,295 $ 20,629 Infrastructure mechanisms (1) 167,965 229,996 Winter Storm Uri incremental costs 28,328 32,115 Deferred gas costs 129,891 148,297 Regulatory excess deferred taxes (2) 47,772 47,549 Recoverable loss on reacquired debt 3,196 3,238 Deferred pipeline record collection costs 59,830 54,008 Other 16,518 19,096 $ 471,795 $ 554,928 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 343,075 $ 384,513 Regulatory cost of removal obligation 584,640 582,867 Deferred gas costs 20,889 23,093 APT annual adjustment mechanism 47,768 49,894 Pension and postretirement benefit costs 211,600 215,913 Other 28,777 28,054 $ 1,236,749 $ 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)	3 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Income statements and capital expenditures for the three months ended December 31, 2023 and 2022 by segment are presented in the following tables: Three Months Ended December 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,104,619 $ 53,848 $ — $ 1,158,467 Intersegment revenues 719 157,321 (158,040) — Total operating revenues 1,105,338 211,169 (158,040) 1,158,467 Purchased gas cost 496,662 4 (157,797) 338,869 Operation and maintenance expense 127,615 38,973 (243) 166,345 Depreciation and amortization expense 119,685 44,923 — 164,608 Taxes, other than income 80,895 8,645 — 89,540 Operating income 280,481 118,624 — 399,105 Other non-operating income 5,839 12,047 — 17,886 Interest charges 34,581 17,294 — 51,875 Income before income taxes 251,739 113,377 — 365,116 Income tax expense 30,302 23,522 — 53,824 Net income $ 221,437 $ 89,855 $ — $ 311,292 Capital expenditures $ 539,158 $ 230,492 $ — $ 769,650 Three Months Ended December 31, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,439,693 $ 44,316 $ — $ 1,484,009 Intersegment revenues 733 142,313 (143,046) — Total operating revenues 1,440,426 186,629 (143,046) 1,484,009 Purchased gas cost 881,915 (858) (142,808) 738,249 Operation and maintenance expense 136,469 48,785 (238) 185,016 Depreciation and amortization expense 105,664 40,356 — 146,020 Taxes, other than income 84,622 8,916 — 93,538 Operating income 231,756 89,430 — 321,186 Other non-operating income 6,774 14,417 — 21,191 Interest charges 22,839 13,921 — 36,760 Income before income taxes 215,691 89,926 — 305,617 Income tax expense 21,223 12,534 — 33,757 Net income $ 194,468 $ 77,392 $ — $ 271,860 Capital expenditures $ 443,544 $ 352,116 $ — $ 795,660 Balance sheet information at December 31, 2023 and September 30, 2023 by segment is presented in the following tables: December 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Net property, plant and equipment $ 14,907,406 $ 5,412,075 $ — $ 20,319,481 Total assets $ 22,874,926 $ 5,721,542 $ (4,912,225) $ 23,684,243 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)	3 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted earnings per share for the three months ended December 31, 2023 and 2022 are calculated as follows: Three Months Ended December 31 2023 2022 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 311,292 $ 271,860 Less: Income allocated to participating securities 186 167 Income available to common shareholders $ 311,106 $ 271,693 Basic weighted average shares outstanding 149,796 141,820 Net income per share — Basic $ 2.08 $ 1.92 Diluted Earnings Per Share Income available to common shareholders $ 311,106 $ 271,693 Effect of dilutive shares — — Income available to common shareholders $ 311,106 $ 271,693 Basic weighted average shares outstanding 149,796 141,820 Dilutive shares — 117 Diluted weighted average shares outstanding 149,796 141,937 Net income per share — Diluted $ 2.08 $ 1.91

Revenue and Accounts Receivab_2

Revenue and Accounts Receivable (Tables)	3 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	The following tables disaggregate our revenue from contracts with customers by customer type and segment and provide a reconciliation to total operating revenues, including intersegment revenues, for the three months ended December 31, 2023 and 2022. Three Months Ended December 31, 2023 Three Months Ended December 31, 2022 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 727,682 $ — $ 953,051 $ — Commercial 277,253 — 388,667 — Industrial 28,231 — 59,215 — Public authority and other 14,584 — 22,826 — Total gas sales revenues 1,047,750 — 1,423,759 — Transportation revenues 33,767 215,305 32,162 195,252 Miscellaneous revenues 2,643 3,042 2,282 2,722 Revenues from contracts with customers 1,084,160 218,347 1,458,203 197,974 Alternative revenue program revenues 17,401 (7,178) (18,322) (11,345) Other revenues 3,777 — 545 — Total operating revenues $ 1,105,338 $ 211,169 $ 1,440,426 $ 186,629
Schedule of Allowance for Credit Loss Activity	Rollforwards of our allowance for uncollectible accounts for the three months ended December 31, 2023 and 2022 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 December 31, 2023 (In thousands) Beginning balance, September 30, 2023 $ 40,840 Current period provisions 6,750 Write-offs charged against allowance (8,757) Recoveries of amounts previously written off 765 Mississippi recovery of uncollectible accounts (4,192) Ending balance, December 31, 2023 $ 35,406 Three Months Ended December 31, 2022 (In thousands) Beginning balance, September 30, 2022 $ 49,993 Current period provisions 7,233 Write-offs charged against allowance (10,421) Recoveries of amounts previously written off 808 Ending balance, December 31, 2022 $ 47,613

Debt (Tables)

Debt (Tables)	3 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt at December 31, 2023 and September 30, 2023 consisted of the following: December 31, 2023 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 400,000 — 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 50,052 50,393 Total long-term debt 7,510,052 6,610,393 Less: Original issue discount on unsecured senior notes and debentures 7,723 6,104 Debt issuance cost 56,573 48,588 Current maturities of long-term debt 1,561 1,568 Total long-term debt, net $ 7,444,195 $ 6,554,133

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Reconciliation of Changes in Stockholders Equity	The following tables present a reconciliation of changes in stockholders' equity for the three months ended December 31, 2023 and 2022. 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 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
Schedule of Forward Sales Agreements	Additionally, we had $473.5 million in available proceeds from outstanding forward sale agreements, as detailed below. Maturity Shares Available Net Proceeds Available Forward Price September 30, 2024 861,655 $ 101,376 $ 117.65 December 31, 2024 2,176,974 250,866 $ 115.24 June 30, 2025 1,061,914 121,230 $ 114.16 Total 4,100,543 $ 473,472 $ 115.47
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 296 (47,741) (47,445) Amounts reclassified from accumulated other comprehensive income — (2,491) (2,491) Net current-period other comprehensive income (loss) 296 (50,232) (49,936) December 31, 2023 $ (73) $ 468,665 $ 468,592 Available- Interest Rate Total (In thousands) September 30, 2022 $ (495) $ 369,607 $ 369,112 Other comprehensive income before reclassifications 87 22,661 22,748 Amounts reclassified from accumulated other comprehensive income — (530) (530) Net current-period other comprehensive income 87 22,131 22,218 December 31, 2022 $ (408) $ 391,738 $ 391,330

Variable Interest Entity (Table

Variable Interest Entity (Tables)	3 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Condensed Consolidated Balance Sheet	The following table summarizes the impact of AEK on our condensed consolidated balance sheets, for the periods indicated: December 31, 2023 September 30, 2023 (In thousands) Restricted cash and cash equivalents $ 7,130 $ 3,844 Other current assets $ 23 $ 11 Securitized intangible asset, net $ 90,036 $ 92,202 Accrued interest $ 2,598 $ 1,374 Current maturities of securitized long-term debt $ 9,922 $ 9,922 Securitized long-term debt $ 85,078 $ 85,078
Condensed Statement of Comprehensive Income	The following table summarizes the impact of AEK on our condensed consolidated statement of comprehensive income, for the period indicated: Three Months Ended December 31, 2023 (In thousands) Operating revenues $ 3,333 Amortization expense (2,166) Interest expense, net (1,167) Income before income taxes $ —

Interim Pension and Other Pos_2

Interim Pension and Other Postretirement Benefit Plan Information (Tables)	3 Months Ended
	Dec. 31, 2023
Retirement Benefits, Description [Abstract]
Schedule of Net Benefit Costs	Three Months Ended December 31 Pension Benefits Other Benefits 2023 2022 2023 2022 (In thousands) Components of net periodic pension cost: Service cost $ 2,389 $ 2,908 $ 1,507 $ 1,546 Interest cost (1) 7,497 7,325 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) 118 164 (2,718) (1,863) Settlements (1) 776 — — — Net periodic pension cost $ 3,578 $ 3,089 $ (4,090) $ (2,928) (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)	3 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Interest Rate Derivatives	The following table summarizes our existing forward starting interest rate swaps as of December 31, 2023. 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 December 31, 2023 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 December 31, 2023 and September 30, 2023, no gross amounts and no cash collateral were netted within our consolidated balance sheet. December 31, 2023 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Other current assets / $ 232,975 $ — Interest rate contracts Deferred charges and other assets / 84,586 — Total 317,561 — Not Designated As Hedges: Commodity contracts Other current assets / 2,545 (19,819) Commodity contracts Deferred charges and other assets / 761 (1,777) Total 3,306 (21,596) Gross / Net Financial Instruments $ 320,867 $ (21,596) 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 months ended December 31, 2023 and 2022. Three Months Ended December 31 2023 2022 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (47,741) $ 22,661 Recognition of (gains) losses in earnings due to settlements: Interest rate agreements (2,491) (530) Total other comprehensive income (loss) from hedging, net of tax $ (50,232) $ 22,131
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 212,342 Total $ 222,307

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of December 31, 2023 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 December 31, 2023 (In thousands) Assets: Financial instruments $ — $ 320,867 $ — $ — $ 320,867 Debt and equity securities Registered investment companies 28,466 — — — 28,466 Bond mutual funds 38,584 — — — 38,584 Bonds (2) — 36,343 — — 36,343 Money market funds — 3,861 — — 3,861 Total debt and equity securities 67,050 40,204 — — 107,254 Total assets $ 67,050 $ 361,071 $ — $ — $ 428,121 Liabilities: Financial instruments $ — $ 21,596 $ — $ — $ 21,596 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 December 31, 2023 and September 30, 2023: December 31, 2023 September 30, 2023 (In thousands) Carrying Amount $ 7,460,000 $ 6,560,000 Fair Value $ 6,963,106 $ 5,402,591

Nature of Business (Details)

Nature of Business (Details) customer in Millions	Dec. 31, 2023 state regulatedDistributionDivision customer
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of customers serviced (over) | customer	3.3
Number of regulated distribution divisions | regulatedDistributionDivision	6
Number of states with service areas | state	8

Regulation - Schedule of Regula

Regulation - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Regulatory Asset [Line Items]
Regulatory assets	$ 471,795	$ 554,928
Regulatory Liabilities [Line Items]
Regulatory liabilities	1,236,749	1,284,334
Regulatory excess deferred taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	343,075	384,513
Regulatory cost of removal obligation
Regulatory Liabilities [Line Items]
Regulatory liabilities	584,640	582,867
Deferred gas costs
Regulatory Liabilities [Line Items]
Regulatory liabilities	20,889	23,093
APT annual adjustment mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities	47,768	49,894
Pension and postretirement benefit costs
Regulatory Liabilities [Line Items]
Regulatory liabilities	211,600	215,913
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	28,777	28,054
Pension and postretirement benefit costs
Regulatory Asset [Line Items]
Regulatory assets	18,295	20,629
Infrastructure mechanisms
Regulatory Asset [Line Items]
Regulatory assets	167,965	229,996
Winter Storm Uri incremental costs
Regulatory Asset [Line Items]
Regulatory assets	28,328	32,115
Deferred gas costs
Regulatory Asset [Line Items]
Regulatory assets	129,891	148,297
Regulatory excess deferred taxes
Regulatory Asset [Line Items]
Regulatory assets	47,772	47,549
Recoverable loss on reacquired debt
Regulatory Asset [Line Items]
Regulatory assets	3,196	3,238
Deferred pipeline record collection costs
Regulatory Asset [Line Items]
Regulatory assets	59,830	54,008
Other
Regulatory Asset [Line Items]
Regulatory assets	$ 16,518	$ 19,096

Regulation - Narrative (Details

Regulation - Narrative (Details) - Texas - Winter Storm Uri - USD ($) $ in Millions		1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 01, 2022	Mar. 31, 2023	Dec. 31, 2023	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			$ 10.9
Winter Storm Uri incremental costs | Other current assets
Regulatory Asset [Line Items]
Regulatory asset, recovering cost			$ 17.4	$ 21.2

Segment Information - Narrative

Segment Information - Narrative (Details)	Dec. 31, 2023 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
	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 1,158,467	$ 1,484,009
Purchased gas cost	338,869	738,249
Operation and maintenance expense	166,345	185,016
Depreciation and amortization expense	164,608	146,020
Taxes, other than income	89,540	93,538
Operating income	399,105	321,186
Other non-operating income	17,886	21,191
Interest charges	51,875	36,760
Income before income taxes	365,116	305,617
Income tax expense	53,824	33,757
Net income	311,292	271,860
Capital expenditures	769,650	795,660
Distribution segment
Segment Reporting Information [Line Items]
Operating revenues	1,104,619	1,439,693
Pipeline and storage segment
Segment Reporting Information [Line Items]
Operating revenues	53,848	44,316
Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(158,040)	(143,046)
Purchased gas cost	(157,797)	(142,808)
Operation and maintenance expense	(243)	(238)
Depreciation and amortization expense	0	0
Taxes, other than income	0	0
Operating income	0	0
Other non-operating income	0	0
Interest charges	0	0
Income before income taxes	0	0
Income tax expense	0	0
Net income	0	0
Capital expenditures	0	0
Eliminations | Distribution segment
Segment Reporting Information [Line Items]
Operating revenues	719	733
Eliminations | Pipeline and storage segment
Segment Reporting Information [Line Items]
Operating revenues	157,321	142,313
Operating Segments | Distribution segment
Segment Reporting Information [Line Items]
Operating revenues	1,105,338	1,440,426
Purchased gas cost	496,662	881,915
Operation and maintenance expense	127,615	136,469
Depreciation and amortization expense	119,685	105,664
Taxes, other than income	80,895	84,622
Operating income	280,481	231,756
Other non-operating income	5,839	6,774
Interest charges	34,581	22,839
Income before income taxes	251,739	215,691
Income tax expense	30,302	21,223
Net income	221,437	194,468
Capital expenditures	539,158	443,544
Operating Segments | Pipeline and storage segment
Segment Reporting Information [Line Items]
Operating revenues	211,169	186,629
Purchased gas cost	4	(858)
Operation and maintenance expense	38,973	48,785
Depreciation and amortization expense	44,923	40,356
Taxes, other than income	8,645	8,916
Operating income	118,624	89,430
Other non-operating income	12,047	14,417
Interest charges	17,294	13,921
Income before income taxes	113,377	89,926
Income tax expense	23,522	12,534
Net income	89,855	77,392
Capital expenditures	$ 230,492	$ 352,116

Segment Information - Schedul_2

Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Segment Reporting Information [Line Items]
Net property, plant and equipment	$ 20,319,481	$ 19,606,583
Total assets	23,684,243	22,516,968
Operating Segments | Distribution
Segment Reporting Information [Line Items]
Net property, plant and equipment	14,907,406	14,402,578
Total assets	22,874,926	21,716,467
Operating Segments | Pipeline and Storage
Segment Reporting Information [Line Items]
Net property, plant and equipment	5,412,075	5,204,005
Total assets	5,721,542	5,504,972
Eliminations
Segment Reporting Information [Line Items]
Net property, plant and equipment	0	0
Total assets	$ (4,912,225)	$ (4,704,471)

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Basic Earnings Per Share
Net income	$ 311,292	$ 271,860
Less: Income allocated to participating securities	186	167
Income available to common shareholders	$ 311,106	$ 271,693
Basic weighted average shares outstanding (in shares)	149,796	141,820
Net income per share - Basic (USD per share)	$ 2.08	$ 1.92
Diluted Earnings Per Share
Income available to common shareholders	$ 311,106	$ 271,693
Effect of dilutive shares	0	0
Income available to common shareholders	$ 311,106	$ 271,693
Basic weighted average shares outstanding (in shares)	149,796	141,820
Dilutive shares (in shares)	0	117
Diluted weighted average shares outstanding (in shares)	149,796	141,937
Net income per share - Diluted (USD per share)	$ 2.08	$ 1.91

Revenue and Accounts Receivab_3

Revenue and Accounts Receivable - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 1,158,467	$ 1,484,009
Distribution
Disaggregation of Revenue [Line Items]
Total operating revenues	1,104,619	1,439,693
Pipeline and Storage
Disaggregation of Revenue [Line Items]
Total operating revenues	53,848	44,316
Operating Segments | Distribution
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,084,160	1,458,203
Alternative revenue program revenues	17,401	(18,322)
Other revenues	3,777	545
Total operating revenues	1,105,338	1,440,426
Operating Segments | Distribution | Gas sales revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,047,750	1,423,759
Operating Segments | Distribution | Gas sales revenues | Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	727,682	953,051
Operating Segments | Distribution | Gas sales revenues | Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	277,253	388,667
Operating Segments | Distribution | Gas sales revenues | Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	28,231	59,215
Operating Segments | Distribution | Gas sales revenues | Public authority and other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	14,584	22,826
Operating Segments | Distribution | Transportation revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	33,767	32,162
Operating Segments | Distribution | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,643	2,282
Operating Segments | Pipeline and Storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	218,347	197,974
Alternative revenue program revenues	(7,178)	(11,345)
Other revenues	0	0
Total operating revenues	211,169	186,629
Operating Segments | Pipeline and Storage | Gas sales revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Operating Segments | Pipeline and Storage | Gas sales revenues | Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Operating Segments | Pipeline and Storage | Gas sales revenues | Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Operating Segments | Pipeline and Storage | Gas sales revenues | Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Operating Segments | Pipeline and Storage | Gas sales revenues | Public authority and other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Operating Segments | Pipeline and Storage | Transportation revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	215,305	195,252
Operating Segments | Pipeline and Storage | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 3,042	$ 2,722

Revenue and Accounts Receivab_4

Revenue and Accounts Receivable - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		21 Months Ended
	Nov. 30, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Percent of customers excluded			88%	88%
Reduction to bad debt expense			$ (6,750)	$ (7,233)
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		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 (in percent)			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
	Dec. 31, 2023	Dec. 31, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 40,840	$ 49,993
Current period provisions	6,750	7,233
Write-offs charged against allowance	(8,757)	(10,421)
Recoveries of amounts previously written off	765	808
Mississippi recovery of uncollectible accounts	(4,192)
Ending balance	$ 35,406	$ 47,613

Debt - Schedule of Long-term De

Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Debt Instrument [Line Items]
Long-term debt	$ 7,460,000	$ 6,560,000
Finance lease obligations	50,052	50,393
Total long-term debt	7,510,052	6,610,393
Less:
Original issue discount on unsecured senior notes and debentures	7,723	6,104
Debt issuance cost	56,573	48,588
Current maturities of long-term debt	1,561	1,568
Total long-term debt, net	$ 7,444,195	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	$ 400,000	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)		3 Months Ended
	Oct. 10, 2023 USD ($)	Dec. 31, 2023 USD ($) creditFacility	Dec. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)
Line Of Credit Facility [Line Items]
Proceeds from issuance of long-term debt		$ 898,275,000	$ 797,258,000
Maximum debt-to-total-capitalization ratio		70%
Debt-to-total-capitalization ratio		0.41
Minimum
Line Of Credit Facility [Line Items]
Outstanding indebtedness		$ 15,000,000
Maximum
Line Of Credit Facility [Line Items]
Outstanding indebtedness		100,000,000
Unsecured 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 Senior Notes Due October 2033 | Senior Notes
Line Of Credit Facility [Line Items]
Debt face amount	$ 400,000,000
Interest rate	5.90%
Effective rate	4.35%
Unsecured Senior Notes Due October 2033 and Unsecured Senior Notes Due October 2053 | Senior Notes
Line Of Credit Facility [Line Items]
Proceeds from issuance of long-term debt	$ 889,400,000
Five Year Unsecured Revolving Credit Agreement
Line Of Credit Facility [Line Items]
Outstanding commercial paper		$ 0		$ 241,900,000
Five Year Unsecured Revolving Credit Agreement | Minimum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0%
Five Year Unsecured Revolving Credit Agreement | Minimum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		0.75%
Five Year Unsecured Revolving Credit Agreement | Maximum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0.25%
Five Year Unsecured Revolving Credit Agreement | Maximum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		1.25%
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
Accordion feature		$ 250,000,000
Maximum borrowing capacity post accordion feature		1,750,000,000
Five Year Unsecured Revolving Credit Agreement | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 2,500,000,000
Number of credit facilities | creditFacility		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
Accordion feature		$ 100,000,000
Maximum borrowing capacity post accordion feature		1,000,000,000
Outstanding borrowings		$ 0		0
$900 Million Revolving Credit Facility | Revolving Credit Facility | Minimum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0%
$900 Million Revolving Credit Facility | Revolving Credit Facility | Minimum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		0.75%
$900 Million Revolving Credit Facility | Revolving Credit Facility | Maximum | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread		0.25%
$900 Million Revolving Credit Facility | Revolving Credit Facility | Maximum | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread		1.25%
$50 Million Bank Loan Agreement | Line of Credit
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 50,000,000
Debt agreement term		364 days
Outstanding borrowings		$ 0		$ 0
$50 Million Revolving Credit Facility
Line Of Credit Facility [Line Items]
Outstanding borrowings		0
$50 Million Revolving Credit Facility | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity		$ 50,000,000
Debt agreement term		364 days
Remaining borrowing capacity		$ 44,400,000

Shareholders' Equity - Schedule

Shareholders' Equity - Schedule of Components of Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	148,492,783
Shareholders' equity, beginning balance	$ 10,870,064	$ 9,419,091
Net income	311,292	271,860
Other comprehensive income (loss)	(49,936)	22,218
Cash dividends	(119,898)	(104,552)
Public and other stock offerings	257,768	223,779
Stock-based compensation plans	$ 3,919	3,878
Common stock outstanding, ending balance (in shares)	150,834,397
Shareholders' equity, ending balance	$ 11,273,209	$ 9,836,274
Cash dividends per share (USD per share)	$ 0.805	$ 0.740
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	148,492,783	140,896,598
Shareholders' equity, beginning balance	$ 742	$ 704
Public and other stock offerings (in shares)	2,177,864	2,147,210
Public and other stock offerings	$ 11	$ 11
Stock-based compensation plans (in shares)	163,750	111,953
Stock-based compensation plans	$ 1	$ 1
Common stock outstanding, ending balance (in shares)	150,834,397	143,155,761
Shareholders' equity, ending balance	$ 754	$ 716
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	6,684,120	5,838,118
Public and other stock offerings	257,757	223,768
Stock-based compensation plans	3,918	3,877
Shareholders' equity, ending balance	6,945,795	6,065,763
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	518,528	369,112
Other comprehensive income (loss)	(49,936)	22,218
Shareholders' equity, ending balance	468,592	391,330
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	3,666,674	3,211,157
Net income	311,292	271,860
Cash dividends	(119,898)	(104,552)
Shareholders' equity, ending balance	$ 3,858,068	$ 3,378,465

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details) - USD ($)	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Forward sales equity agreement, settlement in cash	$ 473,472,000
Net proceeds from equity issuances	254,022,000	$ 220,000,000
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	3,100,000,000
At-The-Market
Class of Stock [Line Items]
Value of shares authorized for issuance	$ 1,000,000,000
Forward sales equity agreement (in shares)	2,284,076
Forward sales equity agreement, settlement in cash	$ 261,400,000
Shares issued (in shares)	2,144,558
Net proceeds from equity issuances	$ 254,000,000
Equity available for issuance	$ 499,100,000

Shareholders' Equity - Schedu_2

Shareholders' Equity - Schedule of Forward Sales Agreement (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	4,100,543
Net proceeds available | $	$ 473,472
Forward price (USD per share) | $ / shares	$ 115.47
Forward Sales Equity Agreement Maturing Quarter Ended September 30 2024
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	861,655
Net proceeds available | $	$ 101,376
Forward price (USD per share) | $ / shares	$ 117.65
Forward Sales Equity Agreement Maturing Quarter Ended December 31, 2024
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	2,176,974
Net proceeds available | $	$ 250,866
Forward price (USD per share) | $ / shares	$ 115.24
Forward Sales Equity Agreement Maturing Quarter Ended June 30, 2025
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	1,061,914
Net proceeds available | $	$ 121,230
Forward price (USD per share) | $ / shares	$ 114.16

Shareholders' Equity - Schedu_3

Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	$ 10,870,064	$ 9,419,091
Other comprehensive income (loss) before reclassifications	(47,445)	22,748
Amounts reclassified from accumulated other comprehensive income	(2,491)	(530)
Total other comprehensive income (loss)	(49,936)	22,218
Shareholders' equity, ending balance	11,273,209	9,836,274
Available- for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	(369)	(495)
Other comprehensive income (loss) before reclassifications	296	87
Amounts reclassified from accumulated other comprehensive income	0	0
Total other comprehensive income (loss)	296	87
Shareholders' equity, ending balance	(73)	(408)
Interest Rate Agreement Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	518,897	369,607
Other comprehensive income (loss) before reclassifications	(47,741)	22,661
Amounts reclassified from accumulated other comprehensive income	(2,491)	(530)
Total other comprehensive income (loss)	(50,232)	22,131
Shareholders' equity, ending balance	468,665	391,738
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	518,528	369,112
Total other comprehensive income (loss)	(49,936)	22,218
Shareholders' equity, ending balance	$ 468,592	$ 391,330

Variable Interest Entity - Narr

Variable Interest Entity - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023
Variable Interest Entity [Line Items]
Long-term debt, fair value	$ 6,963,106	$ 5,402,591
Securitized Utility Tariff Bonds | Senior Notes | AEK | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Debt face amount			$ 95,000
Long-term debt	95,000
Long-term debt, fair value	$ 96,200

Variable Interest Entity - Sche

Variable Interest Entity - Schedule of Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Variable Interest Entity [Line Items]
Restricted cash and cash equivalents	$ 7,130	$ 3,844
Other current assets	526,927	292,036
Securitized intangible asset, net	90,036	92,202
Current maturities of securitized long-term debt	9,922	9,922
Securitized long-term debt	85,078	85,078
Variable Interest Entity, Primary Beneficiary | AEK
Variable Interest Entity [Line Items]
Restricted cash and cash equivalents	7,130	3,844
Other current assets	23	11
Securitized intangible asset, net	90,036	92,202
Accrued interest	2,598	1,374
Current maturities of securitized long-term debt	9,922	9,922
Securitized long-term debt	$ 85,078	$ 85,078

Variable Interest Entity - Cons

Variable Interest Entity - Consolidated Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Operating revenues	$ 1,158,467	$ 1,484,009
Amortization expense	(164,608)	(146,020)
Interest expense, net	(51,875)	(36,760)
Income before income taxes	365,116	$ 305,617
Variable Interest Entity, Primary Beneficiary | AEK
Variable Interest Entity [Line Items]
Operating revenues	3,333
Amortization expense	(2,166)
Interest expense, net	(1,167)
Income before income taxes	$ 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	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2024
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			$ 776	$ 0

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
	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,389	$ 2,908
Interest cost	7,497	7,325
Expected return on assets	(7,202)	(7,278)
Amortization of prior service cost (credit)	0	(30)
Amortization of actuarial (gain) loss	118	164
Settlements	(776)	0
Net periodic pension cost	3,578	3,089
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,507	1,546
Interest cost	3,509	3,478
Expected return on assets	(3,128)	(2,804)
Amortization of prior service cost (credit)	(3,260)	(3,285)
Amortization of actuarial (gain) loss	(2,718)	(1,863)
Settlements	0	0
Net periodic pension cost	$ (4,090)	$ (2,928)

Commitments and Contingencies (

Commitments and Contingencies (Details)	3 Months Ended
	Dec. 31, 2023 $ / Mcf MMcf	Jan. 24, 2024 fatality
Subsequent Event | National Transportation Safety Board
Long-term Purchase Commitment [Line Items]
Number of fatalities under investigation | fatality		1
Supply Commitment
Long-term Purchase Commitment [Line Items]
Contract term	1 year
Purchase commitment volume	12,500
Supply Commitment | Weighted Average
Long-term Purchase Commitment [Line Items]
Fixed price contracts (USD per Mcf) | $ / Mcf	2.89
Supply Commitment | Short-term Contract with Customer
Long-term Purchase Commitment [Line Items]
Contract term	1 year
Purchase commitment volume	71,800
Supply Commitment | Long-term Contract with Customer Within Two To Three Years
Long-term Purchase Commitment [Line Items]
Purchase commitment volume	51,300
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
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023
Income Tax Contingency [Line Items]
Effective income tax rate	14.70%	11%
Regulatory liabilities	$ 1,236,749		$ 1,284,334
Regulatory excess deferred taxes
Income Tax Contingency [Line Items]
Deferred tax liabilities, net	295,300
Regulatory liabilities	343,075		384,513
Regulatory excess deferred taxes | Other Current Liabilities
Income Tax Contingency [Line Items]
Deferred tax liabilities, net	111,100		$ 131,300
Regulatory excess deferred taxes, to be returned, tranche one
Income Tax Contingency [Line Items]
Deferred tax liabilities, net	$ 241,900
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	$ 52,400
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

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	3 Months Ended
	Dec. 31, 2023 USD ($) MMcf	Dec. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)
Derivative [Line Items]
Purchase commitment volume | MMcf	20,045
Contract netting	$ 0		$ 0
Cash collateral	0		$ 0
Net (gain) loss on settled interest rate agreements	(3,200,000)	$ (700,000)
Net realized gains in AOCI	$ 222,300,000
Not Designated As Hedges: | Gas Purchases | Commodity contracts
Derivative [Line Items]
Purchase commitment volume | MMcf	30,200
Not Designated As Hedges: | Gas Purchases | Commodity contracts | Minimum
Derivative [Line Items]
Hedging percent	25%
Not Designated As Hedges: | Gas Purchases | Commodity contracts | Maximum
Derivative [Line Items]
Hedging percent	50%

Financial Instruments - Schedul

Financial Instruments - Schedule of Interest Rate Risk Management Activities (Details) - Cash Flow Hedging - Designated As Hedge $ in Thousands	Dec. 31, 2023 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	Dec. 31, 2023	Sep. 30, 2023
Derivatives Fair Value [Line Items]
Net financial instruments, assets	$ 320,867	$ 385,664
Net financial instruments, liabilities	(21,596)	(15,408)
Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	317,561	379,101
Gross financial instruments, liabilities	0	0
Designated As Hedges: | Other current assets | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	232,975
Designated As Hedges: | Other current liabilities | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, liabilities	0
Designated As Hedges: | Deferred charges and other assets | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	84,586	379,101
Designated As Hedges: | Deferred credits and other liabilities | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, liabilities	0	0
Not Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	3,306	6,563
Gross financial instruments, liabilities	(21,596)	(15,408)
Not Designated As Hedges: | Other current assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	2,545	4,071
Not Designated As Hedges: | Other current liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, liabilities	(19,819)	(14,584)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	761	2,492
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, liabilities	$ (1,777)	$ (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
	Dec. 31, 2023	Dec. 31, 2022
Increase (decrease) in fair value:
Interest rate agreements	$ (47,741)	$ 22,661
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements	(2,491)	(530)
Total other comprehensive income (loss) from hedging, net of tax	$ (50,232)	$ 22,131

Financial Instruments - Sched_4

Financial Instruments - Schedule Of Expected Deferred Gains (Losses) Recognition (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2023 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Next twelve months	$ 9,965
Thereafter	212,342
Total	$ 222,307

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial instruments net assets	$ 320,867	$ 385,664
Debt and equity securities	107,254	104,602
Total assets	428,121	490,266
Financial instruments net liability	21,596	15,408
Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	28,466	26,685
Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	38,584	37,573
Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	36,343	35,507
Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	3,861	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	67,050	64,258
Total assets	67,050	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	28,466	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	38,584	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	320,867	385,664
Debt and equity securities	40,204	40,344
Total assets	361,071	426,008
Financial instruments gross liability	21,596	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	36,343	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	3,861	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 ($)	Dec. 31, 2023	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Allowance for credit losses	$ 0
Cost basis	$ 36,400,000	$ 36,000,000

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Carrying Amount	$ 7,460,000	$ 6,560,000
Fair Value	$ 6,963,106	$ 5,402,591