Atmos Energy (ATO) 10-Q 3 May 23 2023 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Mar. 31, 2023	Apr. 28, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 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)		144,487,306
Entity Central Index Key	0000731802
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
ASSETS
Property, plant and equipment	$ 21,582,327	$ 20,238,139
Less accumulated depreciation and amortization	3,136,441	2,997,900
Net property, plant and equipment	18,445,886	17,240,239
Current assets
Cash and cash equivalents	95,175	51,554
Accounts receivable, net (See Note 5)	523,741	363,708
Gas stored underground	183,467	357,941
Other current assets (See Note 8)	270,723	2,274,490
Total current assets	1,073,106	3,047,693
Goodwill	731,257	731,257
Deferred charges and other assets (See Note 8)	1,061,612	1,173,800
Total assets	21,311,861	22,192,989
Shareholders’ equity
Common stock, no par value (stated at $0.005 per share); 200,000,000 shares authorized; issued and outstanding: March 31, 2023 — 144,484,650 shares; September 30, 2022 — 140,896,598 shares	722	704
Additional paid-in capital	6,213,523	5,838,118
Accumulated other comprehensive income	360,997	369,112
Retained earnings	3,629,963	3,211,157
Shareholders’ equity	10,205,205	9,419,091
Long-term debt	6,553,097	5,760,647
Total capitalization	16,758,302	15,179,738
Current liabilities
Accounts payable and accrued liabilities	364,973	496,019
Other current liabilities	746,512	720,157
Short-term debt	0	184,967
Current maturities of long-term debt	1,512	2,201,457
Total current liabilities	1,112,997	3,602,600
Deferred income taxes	2,135,738	1,999,505
Regulatory excess deferred taxes	315,071	385,213
Regulatory cost of removal obligation	481,723	487,631
Deferred credits and other liabilities	508,030	538,302
Total capitalization and liabilities	$ 21,311,861	$ 22,192,989

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2023	Sep. 30, 2022
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)	144,484,650	140,896,598
Common stock outstanding (in shares)	144,484,650	140,896,598

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Operating revenues	$ 1,540,973	$ 1,649,819	$ 3,024,982	$ 2,662,605
Purchased gas cost	666,211	871,378	1,404,460	1,242,541
Operation and maintenance expense	194,716	163,352	379,732	322,462
Depreciation and amortization expense	148,317	133,374	294,337	261,230
Taxes, other than income	109,091	96,583	202,629	175,379
Operating income	422,638	385,132	743,824	660,993
Other non-operating income	17,406	5,213	38,597	13,915
Interest charges	37,370	28,928	74,130	48,779
Income before income taxes	402,674	361,417	708,291	626,129
Income tax expense	45,003	36,418	78,760	51,921
Net income	$ 357,671	$ 324,999	$ 629,531	$ 574,208
Basic net income per share (USD per share)	$ 2.48	$ 2.37	$ 4.40	$ 4.24
Diluted net income per share (USD per share)	2.48	2.37	4.40	4.24
Cash dividends per share (USD per share)	$ 0.74	$ 0.68	$ 1.48	$ 1.36
Basic weighted average shares outstanding (in shares)	143,941	136,834	142,881	135,259
Diluted weighted average shares outstanding (in shares)	143,987	137,250	142,963	135,470
Other comprehensive income (loss), net of tax
Net unrealized holding gains (losses) on available-for-sale securities	$ 134	$ (161)	$ 221	$ (230)
Cash flow hedges:
Amortization and unrealized gains (losses) on interest rate agreements	(30,467)	121,884	(8,336)	76,006
Total other comprehensive income (loss)	(30,333)	121,723	(8,115)	75,776
Total comprehensive income	327,338	446,722	621,416	649,984
Distribution segment
Operating revenues	1,499,437	1,609,667	2,939,130	2,581,303
Pipeline and storage segment
Operating revenues	41,536	40,152	85,852	81,302
Purchased gas cost
Purchased gas cost	666,211	871,378	1,404,460	1,242,541
Operating Segments | Distribution segment
Operating revenues	1,500,210	1,610,546	2,940,636	2,582,968
Purchased gas cost	809,023	993,854	1,690,938	1,490,653
Operation and maintenance expense	151,353	121,541	287,822	244,825
Depreciation and amortization expense	106,310	96,612	211,974	189,409
Taxes, other than income	98,200	87,236	182,822	156,281
Operating income	335,324	311,303	567,080	501,800
Other non-operating income	7,465	549	14,239	2,465
Interest charges	21,420	15,157	44,259	23,705
Income before income taxes	321,369	296,695	537,060	480,560
Income tax expense	32,895	27,844	54,118	32,138
Net income	288,474	268,851	482,942	448,422
Operating Segments | Pipeline and storage segment
Operating revenues	184,424	163,747	371,053	326,665
Purchased gas cost	621	1,683	(237)	(1,728)
Operation and maintenance expense	43,591	42,126	92,376	78,281
Depreciation and amortization expense	42,007	36,762	82,363	71,821
Taxes, other than income	10,891	9,347	19,807	19,098
Operating income	87,314	73,829	176,744	159,193
Other non-operating income	9,941	4,664	24,358	11,450
Interest charges	15,950	13,771	29,871	25,074
Income before income taxes	81,305	64,722	171,231	145,569
Income tax expense	12,108	8,574	24,642	19,783
Net income	69,197	56,148	146,589	125,786
Operating Segments | Purchased gas cost | Distribution segment
Purchased gas cost	809,023	993,854	1,690,938	1,490,653
Operating Segments | Purchased gas cost | Pipeline and storage segment
Purchased gas cost	621	1,683	(237)	(1,728)
Intersegment eliminations
Operating revenues	(143,661)	(124,474)	(286,707)	(247,028)
Purchased gas cost	(143,433)	(124,159)	(286,241)	(246,384)
Operation and maintenance expense	(228)	(315)	(466)	(644)
Depreciation and amortization expense	0	0	0	0
Taxes, other than income	0	0	0	0
Operating income	0	0	0	0
Other non-operating income	0	0	0	0
Interest charges	0	0	0	0
Income before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Net income	0	0	0	0
Intersegment eliminations | Distribution segment
Operating revenues	773	879	1,506	1,665
Intersegment eliminations | Pipeline and storage segment
Operating revenues	142,888	123,595	285,201	245,363
Intersegment eliminations | Purchased gas cost
Purchased gas cost	$ (143,433)	$ (124,159)	$ (286,241)	$ (246,384)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Net unrealized holding gains (losses) on available-for-sale securities, tax	$ 39	$ (47)	$ 64	$ (67)
Amortization and unrealized gains (losses) on interest rate agreements, tax	$ (8,806)	$ 35,228	$ (2,409)	$ 21,968

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash Flows From Operating Activities
Net income	$ 629,531	$ 574,208
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	294,337	261,230
Deferred income taxes	59,060	40,122
Other	(27,496)	(12,812)
Net assets / liabilities from risk management activities	(1,482)	(4,172)
Net change in Winter Storm Uri current regulatory asset (See Note 8)	2,021,889	0
Net change in other operating assets and liabilities	(83,123)	(218,092)
Net cash provided by operating activities	2,892,716	640,484
Cash Flows From Investing Activities
Capital expenditures	(1,415,349)	(1,190,029)
Debt and equity securities activities, net	(4,560)	3,758
Other, net	9,519	4,302
Net cash used in investing activities	(1,410,390)	(1,181,969)
Cash Flows From Financing Activities
Net decrease in short-term debt	(184,967)	0
Net proceeds from equity issuances	359,683	594,320
Issuance of common stock through stock purchase and employee retirement plans	7,910	8,010
Proceeds from issuance of long-term debt	797,258	798,802
Proceeds from term loan	2,020,000	0
Repayment of term loan	(2,020,000)	0
Repayment of long-term debt	(2,200,000)	(200,000)
Cash dividends paid	(210,725)	(183,944)
Debt issuance costs	(7,864)	(8,196)
Other	0	(1,735)
Net cash provided by (used in) financing activities	(1,438,705)	1,007,257
Net increase in cash and cash equivalents	43,621	465,772
Cash and cash equivalents at beginning of period	51,554	116,723
Cash and cash equivalents at end of period	$ 95,175	$ 582,495

Nature of Business

Nature of Business	6 Months Ended
	Mar. 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 March 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.

Unaudited Financial Information

Unaudited Financial Information	6 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Unaudited Financial Information	Unaudited Financial Information 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, 2022. 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, 2022. Because of seasonal and other factors, the results of operations for the six-month period ended March 31, 2023 are not indicative of our results of operations for the full 2023 fiscal year, which ends September 30, 2023. Except as described in Note 6 and Note 12 to the unaudited condensed consolidated financial statements, no events have occurred subsequent to the balance sheet date that would require recognition or disclosure in the unaudited condensed consolidated financial statements. 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, 2022. During the second quarter of fiscal 2023, we completed our annual goodwill impairment assessment using a qualitative assessment, as permitted under U.S. GAAP. We test for goodwill at the reporting unit level on an annual basis and between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of the reporting unit. Based on the assessment performed, we determined that our goodwill was not impaired. Regulatory assets and liabilities 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 March 31, 2023 and September 30, 2022 included the following: March 31, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 24,096 $ 31,122 Infrastructure mechanisms (1) 203,010 235,972 Winter Storm Uri incremental costs (2) 121,493 2,109,454 Deferred gas costs 49,156 119,742 Regulatory excess deferred taxes (3) 47,656 47,311 Recoverable loss on reacquired debt 3,322 3,406 Deferred pipeline record collection costs 51,967 36,898 Other 13,231 21,467 $ 513,931 $ 2,605,372 Regulatory liabilities: Regulatory excess deferred taxes (3) $ 466,496 $ 545,021 Regulatory cost of removal obligation 568,778 568,307 Deferred gas costs 97,407 28,834 Asset retirement obligation 5,737 5,737 APT annual adjustment mechanism 39,360 31,138 Pension and postretirement benefit costs 146,829 156,857 Other 30,703 23,013 $ 1,355,310 $ 1,358,907 (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) Includes extraordinary gas costs incurred during Winter Storm Uri and certain related carrying costs. See Note 8 to the unaudited condensed consolidated financial statements for further information. (3) 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 11 to the unaudited condensed consolidated financial statements for further information.

Segment Information

Segment Information	6 Months Ended
	Mar. 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, 2022. Income statements and capital expenditures for the three and six months ended March 31, 2023 and 2022 by segment are presented in the following tables: Three Months Ended March 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,499,437 $ 41,536 $ — $ 1,540,973 Intersegment revenues 773 142,888 (143,661) — Total operating revenues 1,500,210 184,424 (143,661) 1,540,973 Purchased gas cost 809,023 621 (143,433) 666,211 Operation and maintenance expense 151,353 43,591 (228) 194,716 Depreciation and amortization expense 106,310 42,007 — 148,317 Taxes, other than income 98,200 10,891 — 109,091 Operating income 335,324 87,314 — 422,638 Other non-operating income 7,465 9,941 — 17,406 Interest charges 21,420 15,950 — 37,370 Income before income taxes 321,369 81,305 — 402,674 Income tax expense 32,895 12,108 — 45,003 Net income $ 288,474 $ 69,197 $ — $ 357,671 Capital expenditures $ 424,989 $ 194,700 $ — $ 619,689 Three Months Ended March 31, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,609,667 $ 40,152 $ — $ 1,649,819 Intersegment revenues 879 123,595 (124,474) — Total operating revenues 1,610,546 163,747 (124,474) 1,649,819 Purchased gas cost 993,854 1,683 (124,159) 871,378 Operation and maintenance expense 121,541 42,126 (315) 163,352 Depreciation and amortization expense 96,612 36,762 — 133,374 Taxes, other than income 87,236 9,347 — 96,583 Operating income 311,303 73,829 — 385,132 Other non-operating income 549 4,664 — 5,213 Interest charges 15,157 13,771 — 28,928 Income before income taxes 296,695 64,722 — 361,417 Income tax expense 27,844 8,574 — 36,418 Net income $ 268,851 $ 56,148 $ — $ 324,999 Capital expenditures $ 362,468 $ 143,381 $ — $ 505,849 Six Months Ended March 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,939,130 $ 85,852 $ — $ 3,024,982 Intersegment revenues 1,506 285,201 (286,707) — Total operating revenues 2,940,636 371,053 (286,707) 3,024,982 Purchased gas cost 1,690,938 (237) (286,241) 1,404,460 Operation and maintenance expense 287,822 92,376 (466) 379,732 Depreciation and amortization expense 211,974 82,363 — 294,337 Taxes, other than income 182,822 19,807 — 202,629 Operating income 567,080 176,744 — 743,824 Other non-operating income 14,239 24,358 — 38,597 Interest charges 44,259 29,871 — 74,130 Income before income taxes 537,060 171,231 — 708,291 Income tax expense 54,118 24,642 — 78,760 Net income $ 482,942 $ 146,589 $ — $ 629,531 Capital expenditures $ 868,533 $ 546,816 $ — $ 1,415,349 Six Months Ended March 31, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,581,303 $ 81,302 $ — $ 2,662,605 Intersegment revenues 1,665 245,363 (247,028) — Total operating revenues 2,582,968 326,665 (247,028) 2,662,605 Purchased gas cost 1,490,653 (1,728) (246,384) 1,242,541 Operation and maintenance expense 244,825 78,281 (644) 322,462 Depreciation and amortization expense 189,409 71,821 — 261,230 Taxes, other than income 156,281 19,098 — 175,379 Operating income 501,800 159,193 — 660,993 Other non-operating income 2,465 11,450 — 13,915 Interest charges 23,705 25,074 — 48,779 Income before income taxes 480,560 145,569 — 626,129 Income tax expense 32,138 19,783 — 51,921 Net income $ 448,422 $ 125,786 $ — $ 574,208 Capital expenditures $ 799,850 $ 390,179 $ — $ 1,190,029 Balance sheet information at March 31, 2023 and September 30, 2022 by segment is presented in the following tables: March 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Net property, plant and equipment $ 13,495,410 $ 4,950,476 $ — $ 18,445,886 Total assets $ 20,565,390 $ 5,226,910 $ (4,480,439) $ 21,311,861 September 30, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Net property, plant and equipment $ 12,723,532 $ 4,516,707 $ — $ 17,240,239 Total assets $ 21,424,586 $ 4,797,206 $ (4,028,803) $ 22,192,989

Earnings Per Share

Earnings Per Share	6 Months Ended
	Mar. 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 7 to the unaudited condensed consolidated financial statements, when the impact is dilutive. Basic and diluted earnings per share for the three and six months ended March 31, 2023 and 2022 are calculated as follows: Three Months Ended March 31 Six Months Ended March 31 2023 2022 2023 2022 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 357,671 $ 324,999 $ 629,531 $ 574,208 Less: Income allocated to participating securities 212 202 381 379 Income available to common shareholders $ 357,459 $ 324,797 $ 629,150 $ 573,829 Basic weighted average shares outstanding 143,941 136,834 142,881 135,259 Net income per share — Basic $ 2.48 $ 2.37 $ 4.40 $ 4.24 Diluted Earnings Per Share Income available to common shareholders $ 357,459 $ 324,797 $ 629,150 $ 573,829 Effect of dilutive shares — — — — Income available to common shareholders $ 357,459 $ 324,797 $ 629,150 $ 573,829 Basic weighted average shares outstanding 143,941 136,834 142,881 135,259 Dilutive shares 46 416 82 211 Diluted weighted average shares outstanding 143,987 137,250 142,963 135,470 Net income per share — Diluted $ 2.48 $ 2.37 $ 4.40 $ 4.24

Revenue and Accounts Receivable

Revenue and Accounts Receivable	6 Months Ended
	Mar. 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, 2022. The following tables disaggregate our revenue from contracts with customers by customer type and segment and provide a reconciliation to total operating revenues, including intersegment revenues, for the three and six months ended March 31, 2023 and 2022. Three Months Ended March 31, 2023 Three Months Ended March 31, 2022 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 943,090 $ — $ 1,090,702 $ — Commercial 398,812 — 428,330 — Industrial 45,044 — 54,372 — Public authority and other 22,686 — 26,396 — Total gas sales revenues 1,409,632 — 1,599,800 — Transportation revenues 33,511 190,248 32,801 163,850 Miscellaneous revenues 2,662 1,152 2,680 2,284 Revenues from contracts with customers 1,445,805 191,400 1,635,281 166,134 Alternative revenue program revenues (1) 53,910 (6,976) (25,246) (2,387) Other revenues 495 — 511 — Total operating revenues $ 1,500,210 $ 184,424 $ 1,610,546 $ 163,747 Six Months Ended March 31, 2023 Six Months Ended March 31, 2022 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 1,896,141 $ — $ 1,666,543 $ — Commercial 787,479 — 679,091 — Industrial 104,259 — 103,053 — Public authority and other 45,512 — 41,588 — Total gas sales revenues 2,833,391 — 2,490,275 — Transportation revenues 65,673 385,500 60,670 327,709 Miscellaneous revenues 4,944 3,874 5,279 8,827 Revenues from contracts with customers 2,904,008 389,374 2,556,224 336,536 Alternative revenue program revenues (1) 35,588 (18,321) 25,740 (9,871) Other revenues 1,040 — 1,004 — Total operating revenues $ 2,940,636 $ 371,053 $ 2,582,968 $ 326,665 (1) In our distribution segment, we have weather-normalization adjustment mechanisms that serve to mitigate the effects of weather on our revenue. Additionally, APT has a regulatory mechanism that requires that APT shares with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a revenue benchmark. 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, 2022. During the six months ended March 31, 2023, there were no material changes to this policy. Rollforwards of our allowance for uncollectible accounts for the three and six months ended March 31, 2023 and 2022 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 81 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. Three Months Ended March 31, 2023 (In thousands) Beginning balance, December 31, 2022 $ 47,613 Current period provisions 13,009 Write-offs charged against allowance (8,333) Recoveries of amounts previously written off 462 Ending balance, March 31, 2023 $ 52,751 Three Months Ended March 31, 2022 (In thousands) Beginning balance, December 31, 2021 $ 64,934 Current period provisions 5,705 Write-offs charged against allowance (9,029) Recoveries of amounts previously written off 603 Ending balance, March 31, 2022 $ 62,213 Six Months Ended March 31, 2023 (In thousands) Beginning balance, September 30, 2022 $ 49,993 Current period provisions 20,242 Write-offs charged against allowance (18,754) Recoveries of amounts previously written off 1,270 Ending balance, March 31, 2023 $ 52,751 Six Months Ended March 31, 2022 (In thousands) Beginning balance, September 30, 2021 $ 64,471 Current period provisions 12,075 Write-offs charged against allowance (15,458) Recoveries of amounts previously written off 1,125 Ending balance, March 31, 2022 $ 62,213

Debt

Debt	6 Months Ended
	Mar. 31, 2023
Debt Disclosure [Abstract]
Debt	DebtThe nature and terms of our debt instruments and credit facilities are described in detail in Note 7 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2022. Other than as described below, there were no material changes in the terms of our debt instruments during the six months ended March 31, 2023. Long-term debt at March 31, 2023 and September 30, 2022 consisted of the following: March 31, 2023 September 30, 2022 (In thousands) Unsecured 0.625% Senior Notes, due March 2023 $ — $ 1,100,000 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 — 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 — Floating-rate Senior Notes, due March 2023 — 1,100,000 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 51,133 51,850 Total long-term debt 6,611,133 8,011,850 Less: Original issue discount on unsecured senior notes and debentures 6,271 3,704 Debt issuance cost 50,253 46,042 Current maturities of long-term debt 1,512 2,201,457 $ 6,553,097 $ 5,760,647 On October 3, 2022, we completed a public offering of $500 million of 5.75% senior notes due October 2052, with an effective interest rate of 4.50%, after giving effect to the offering costs and settlement of our interest rate swaps, and $300 million of 5.45% senior notes due October 2032, with an effective interest rate of 5.57%, after giving effect to the offering costs. The net proceeds from the offering, after the underwriting discount and offering expenses, of $789.4 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. The primary source of our funding is our commercial paper program, which 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 March 31, 2023, there were no amounts outstanding under our commercial paper program. At September 30, 2022, there was $185.0 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 March 31, 2023 and September 30, 2022, there were no borrowings outstanding under this facility. Additionally, we have a $50 million 364-day unsecured facility, which was renewed April 1, 2023 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of March 31, 2023 and September 30, 2022. Finally, we have a $50 million 364-day unsecured revolving credit facility, which was renewed March 31, 2023 and is used to issue letters of credit and to provide working capital funding. At March 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. On March 3, 2023, we entered into a term loan agreement for a $2.02 billion senior unsecured term loan facility that would have matured December 31, 2023. The proceeds from the facility, along with cash on hand, were used to repay at maturity on March 9, 2023 our outstanding $1.1 billion senior notes and $1.1 billion floating-rate senior notes. Under the terms of the facility, we were required to prepay the facility prior to maturity upon receiving proceeds from the issuance of certain securities that were part of a utility recovery securitization transaction authorized by the state of Texas. On March 23, 2023, we received those proceeds (see Note 8), and on March 24, 2023 we prepaid the term loan facility, thus terminating the term loan agreement and all obligations thereunder. 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 March 31, 2023, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 40 percent. In addition, both the interest margin and the fee that we pay on unused amounts under certain of these facilities are subject to adjustment depending upon our credit ratings. These credit facilities and our public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as certain of our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or if not paid at maturity. We were in compliance with all of our debt covenants as of March 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	6 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Shareholders' Equity	Shareholders' EquityThe following tables present a reconciliation of changes in stockholders' equity for the three and six months ended March 31, 2023 and 2022. Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2022 140,896,598 $ 704 $ 5,838,118 $ 369,112 $ 3,211,157 $ 9,419,091 Net income — — — — 271,860 271,860 Other comprehensive income — — — 22,218 — 22,218 Cash dividends ($0.74 per share) — — — — (104,552) (104,552) Common stock issued: Public and other stock offerings 2,147,210 11 223,768 — — 223,779 Stock-based compensation plans 111,953 1 3,877 — — 3,878 Balance, December 31, 2022 143,155,761 716 6,065,763 391,330 3,378,465 9,836,274 Net income — — — — 357,671 357,671 Other comprehensive loss — — — (30,333) — (30,333) Cash dividends ($0.74 per share) — — — — (106,173) (106,173) Common stock issued: Public and other stock offerings 1,316,930 6 143,808 — — 143,814 Stock-based compensation plans 11,959 — 3,952 — — 3,952 Balance, March 31, 2023 144,484,650 $ 722 $ 6,213,523 $ 360,997 $ 3,629,963 $ 10,205,205 Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2021 132,419,754 $ 662 $ 5,023,751 $ 69,803 $ 2,812,673 $ 7,906,889 Net income — — — — 249,209 249,209 Other comprehensive loss — — — (45,947) — (45,947) Cash dividends ($0.68 per share) — — — — (90,411) (90,411) Common stock issued: Public and other stock offerings 2,730,115 13 265,848 — — 265,861 Stock-based compensation plans 275,212 2 3,942 — — 3,944 Balance, December 31, 2021 135,425,081 677 5,293,541 23,856 2,971,471 8,289,545 Net income — — — — 324,999 324,999 Other comprehensive income — — — 121,723 — 121,723 Cash dividends ($0.68 per share) — — — — (93,533) (93,533) Common stock issued: Public and other stock offerings 3,509,116 18 336,451 — — 336,469 Stock-based compensation plans 77,832 — 4,028 — — 4,028 Balance, March 31, 2022 139,012,029 $ 695 $ 5,634,020 $ 145,579 $ 3,202,937 $ 8,983,231 Shelf Registration, At-the-Market Equity Sales Program and Equity Issuances On March 31, 2023, we filed 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. This shelf registration statement replaced our previous shelf registration statement which was filed on June 29, 2021. At March 31, 2023, $4.0 billion of securities were available for issuance under this shelf registration statement. On March 31, 2023, we filed a prospectus supplement under the shelf registration statement relating to an at-the-market (ATM) equity sales program under which we may issue and sell shares of our common stock up to an aggregate offering price of $1.0 billion through March 31, 2026 (including shares of common stock that may be sold pursuant to forward sale agreements entered into concurrently with the ATM equity sales program). This ATM equity sales program replaced our previous ATM equity sales program, filed on March 23, 2022. During the six months ended March 31, 2023, we executed forward sales under our ATM equity sales program with various forward sellers who borrowed and sold 2,177,143 shares of our common stock at an aggregate price of $257.0 million. During the six months ended March 31, 2023, we also settled forward sale agreements with respect to 3,394,919 shares that had been borrowed and sold by various forward sellers under the ATM program for net proceeds of $359.7 million. As of March 31, 2023, $1.0 billion of equity was available for issuance under our existing ATM program. Additionally, we had $673.2 million in available proceeds from outstanding forward sale agreements, as detailed below. Maturity Shares Available Net Proceeds Available Forward Price September 29, 2023 1,157,238 $ 132,198 $ 114.24 December 29, 2023 919,898 105,843 $ 115.06 March 28, 2024 2,744,502 319,894 $ 116.56 June 28, 2024 927,939 108,491 $ 116.92 September 30, 2024 58,807 6,792 $ 115.49 Total 5,808,384 $ 673,218 $ 115.90 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, 2022 $ (495) $ 369,607 $ 369,112 Other comprehensive income (loss) before reclassifications 221 (7,276) (7,055) Amounts reclassified from accumulated other comprehensive income — (1,060) (1,060) Net current-period other comprehensive income (loss) 221 (8,336) (8,115) March 31, 2023 $ (274) $ 361,271 $ 360,997 Available- Interest Rate Total (In thousands) September 30, 2021 $ 47 $ 69,756 $ 69,803 Other comprehensive income (loss) before reclassifications (230) 74,518 74,288 Amounts reclassified from accumulated other comprehensive income — 1,488 1,488 Net current-period other comprehensive income (loss) (230) 76,006 75,776 March 31, 2022 $ (183) $ 145,762 $ 145,579

Winter Storm Uri

Winter Storm Uri	6 Months Ended
	Mar. 31, 2023
Unusual or Infrequent Items, or Both [Abstract]
Winter Storm Uri	Winter Storm Uri Overview As described in Note 9 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2022, a historic winter storm impacted supply, market pricing and demand for natural gas in our service territories in mid-February 2021. During this time, the governors of Kansas and Texas each declared a state of emergency, and certain regulatory agencies issued emergency orders that impacted the utility and natural gas industries, including statewide utilities curtailment programs and orders encouraging or requiring jurisdictional natural gas utilities to work to ensure customers were provided with safe and reliable natural gas service. Due to the historic nature of this winter storm, we experienced unforeseeable and unprecedented market pricing for gas costs, which resulted in aggregated natural gas purchases during the month of February of approximately $2.3 billion. These gas costs were paid using funds received from a public offering of debt securities completed in March 2021 of $2.2 billion. On March 3, 2023, we entered into a term loan agreement for a $2.02 billion senior unsecured term loan facility and used the proceeds, along with cash on hand, to repay at maturity the outstanding $2.2 billion senior notes that matured on March 9, 2023. Regulatory Asset Accounting Our purchased gas costs are recoverable through purchased gas cost adjustment mechanisms in each state where we operate. Due to the unprecedented level of purchased gas costs incurred during Winter Storm Uri, the Kansas Corporation Commission (KCC) and the Railroad Commission of Texas (RRC) issued orders authorizing natural gas utilities to record a regulatory asset to account for the extraordinary costs associated with the winter storm. Pursuant to these orders, we recorded a regulatory asset for incremental costs, including certain carrying costs, incurred in Kansas and Texas. As of March 31, 2023, we have recorded an $89.1 million regulatory asset related to costs incurred in Kansas. The regulatory asset that was recorded related to costs incurred in Texas was relieved in March 2023 as a result of securitization proceedings in Texas as discussed below. Additionally, pursuant to a separate regulatory order issued by the RRC, we have deferred $32.4 million in carrying costs incurred after September 1, 2022, which we anticipate recovering in future regulatory filings. We have recorded the regulatory asset for Texas as a long-term asset in deferred charges and other assets as of March 31, 2023. Securitization Proceedings To minimize the impact on the customer bill by extending the recovery periods for these unprecedented purchased gas costs, the Kansas and Texas State Legislatures each enacted securitization legislation during fiscal 2021, as described in further detail in Note 9 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2022. Kansas The KCC issued a financing order on October 25, 2022, which authorizes us to securitize, through the issuance of bonds, $118.5 million, which includes the carrying costs and estimated interest related to the securitization over a time period not to exceed 12 years. We currently expect the issuance of bonds to take place during fiscal 2023. Because we intend to recover these costs over several years, we have recorded the regulatory asset for Kansas as a long-term asset in deferred charges and other assets as of March 31, 2023. Texas On February 8, 2022, the RRC issued a Financing Order that authorizes the Texas Public Financing Authority (TPFA) to issue customer rate relief bonds to securitize the costs that were approved in the Final Determination over a period not to exceed 30 years. The TPFA authorized the creation of the Texas Natural Gas Securitization Finance Corporation (the Finance Corporation) as an issuing financing entity for the purpose of issuing customer rate relief bonds. On March 23, 2023, the Finance Corporation 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. When we begin collecting the customer rate relief charges, such property shall be solely owned by the Finance Corporation and not available to pay creditors of Atmos Energy. On March 23, 2023, we received proceeds from the Finance Corporation in the amount of $2.02 billion, and we relieved $2.02 billion in regulatory assets related to costs incurred in Texas. U.S. GAAP does not provide comprehensive recognition and measurement guidance for many forms of government assistance received by business entities. Accordingly, we have accounted for the proceeds received from the Finance Corporation by analogy to International Accounting Standards No. 20, "Accounting for Government Grants and Disclosure of Government Assistance" consistent with a grant related to income. The proceeds received and the corresponding derecognition of the deferred regulatory asset have been reflected in purchased gas cost and interest charges in our condensed consolidated statements of comprehensive income. As the proceeds reflect the recovery of the regulatory asset, there was no impact to earnings. The proceeds are reflected in our condensed consolidated statements of cash flow as an increase in operating cash flow. As discussed in Note 6, we used the proceeds from the Finance Corporation to repay a term loan facility.

Interim Pension and Other Postr

Interim Pension and Other Postretirement Benefit Plan Information	6 Months Ended
	Mar. 31, 2023
Retirement Benefits, Description [Abstract]
Interim Pension and Other Postretirement Benefit Plan Information	Interim Pension and Other Postretirement Benefit Plan InformationThe components of our net periodic pension cost for our pension and other postretirement benefit plans for the three and six months ended March 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. Three Months Ended March 31 Pension Benefits Other Benefits 2023 2022 2023 2022 (In thousands) Components of net periodic pension cost: Service cost $ 2,908 $ 4,324 $ 1,546 $ 2,558 Interest cost (1) 7,325 5,064 3,478 2,684 Expected return on assets (1) (7,278) (7,383) (2,804) (3,313) Amortization of prior service cost (credit) (1) (30) (58) (3,285) (3,308) Amortization of actuarial (gain) loss (1) 164 1,951 (1,863) — Net periodic pension cost $ 3,089 $ 3,898 $ (2,928) $ (1,379) Six Months Ended March 31 Pension Benefits Other Benefits 2023 2022 2023 2022 (In thousands) Components of net periodic pension cost: Service cost $ 5,816 $ 8,647 $ 3,091 $ 5,117 Interest cost (1) 14,650 10,127 6,955 5,367 Expected return on assets (1) (14,556) (14,766) (5,608) (6,625) Amortization of prior service cost (credit) (1) (61) (116) (6,571) (6,617) Amortization of actuarial (gain) loss (1) 329 3,902 (3,726) — Net periodic pension cost $ 6,178 $ 7,794 $ (5,859) $ (2,758) (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, 2022. For the six months ended March 31, 2023 we contributed $6.2 million to our postretirement medical plans. We anticipate contributing a total of between $15 million and $25 million to our postretirement plans during fiscal 2023.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Mar. 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. 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, 2022. At March 31, 2023, we were committed to purchase 81.2 Bcf within one year, 109.2 Bcf within two Rate Regulatory Proceedings As of March 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 six months ended March 31, 2023.

Income Taxes

Income Taxes	6 Months Ended
	Mar. 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, 2023 and 2022, adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended March 31, 2023 and 2022 were 11.2% and 10.1% and for the six months ended March 31, 2023 and 2022 were 11.1% and 8.3%. 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 $418.9 million is being returned over various periods. Of this amount, $332.2 million is being returned to customers over 35 - 60 months. An additional $71.6 million is being returned to customers on a provisional basis over 15 - 69 years until our regulators establish the final refund periods. The refund of the remaining $15.1 million will be addressed in future rate proceedings. As of March 31, 2023 and September 30, 2022, $151.4 million and $159.8 million is recorded in other current liabilities.

Financial Instruments

Financial Instruments	6 Months Ended
	Mar. 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 15 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2022. During the six months ended March 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 2022-2023 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 32 percent, or 17.7 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. In March 2023, we entered into forward starting interest rate swaps to effectively fix the Treasury yield component associated with $150 million of planned issuances of unsecured senior notes in fiscal 2024. These swaps were designated as cash flow hedges at the time the agreements were executed. The following table summarizes our existing forward starting interest rate swaps as of March 31, 2023. Planned Debt Issuance Date Amount Hedged (In thousands) Fiscal 2024 $ 600,000 Fiscal 2025 600,000 Fiscal 2026 300,000 $ 1,500,000 Additionally, in April 2023, we entered into a forward starting interest rate swap to effectively fix the Treasury yield component associated with $100 million of planned issuances of unsecured senior notes in fiscal 2024. This swap was designated as a cash flow hedge at the time the agreement was executed. 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 March 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 March 31, 2023, we had 4,123 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 March 31, 2023 and September 30, 2022. The gross amounts of recognized assets and liabilities are netted within our unaudited condensed consolidated balance sheets to the extent that we have netting arrangements with our counterparties. However, as of March 31, 2023 and September 30, 2022, no gross amounts and no cash collateral were netted within our consolidated balance sheet. March 31, 2023 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Other current assets / $ 95,735 $ (272) Interest rate contracts Deferred charges and other assets / 250,232 — Total 345,967 (272) Not Designated As Hedges: Commodity contracts Other current assets / 1,974 (11,679) Total 1,974 (11,679) Gross / Net Financial Instruments $ 347,941 $ (11,951) September 30, 2022 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Deferred charges and other assets / $ 355,075 $ — Total 355,075 — Not Designated As Hedges: Commodity contracts Other current assets / 26,207 (3,000) Commodity contracts Deferred charges and other assets / 709 (1,129) Total 26,916 (4,129) Gross / Net Financial Instruments $ 381,991 $ (4,129) 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 March 31, 2023 and 2022 was $(0.7) million and $1.0 million and for the six months ended March 31, 2023 and 2022 was $(1.4) million and $1.9 million. The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and six months ended March 31, 2023 and 2022. Three Months Ended March 31 Six Months Ended March 31 2023 2022 2023 2022 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (29,937) $ 121,140 $ (7,276) $ 74,518 Recognition of (gains) losses in earnings due to settlements: Interest rate agreements (530) 744 (1,060) 1,488 Total other comprehensive income (loss) from hedging, net of tax $ (30,467) $ 121,884 $ (8,336) $ 76,006 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 March 31, 2023, we had $93.1 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 $ 2,120 Thereafter 90,967 Total $ 93,087 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	6 Months Ended
	Mar. 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, accounts receivable and accounts payable 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, 2022. During the six months ended March 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 10 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2022. 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 March 31, 2023 and September 30, 2022. 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 March 31, 2023 (In thousands) Assets: Financial instruments $ — $ 347,941 $ — $ — $ 347,941 Debt and equity securities Registered investment companies 27,596 — — — 27,596 Bond mutual funds 33,326 — — — 33,326 Bonds (2) — 34,962 — — 34,962 Money market funds — 6,458 — — 6,458 Total debt and equity securities 60,922 41,420 — — 102,342 Total assets $ 60,922 $ 389,361 $ — $ — $ 450,283 Liabilities: Financial instruments $ — $ 11,951 $ — $ — $ 11,951 Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and September 30, 2022 (In thousands) Assets: Financial instruments $ — $ 381,991 $ — $ — $ 381,991 Debt and equity securities Registered investment companies 26,367 — — — 26,367 Bond mutual funds 32,367 — — — 32,367 Bonds (2) — 33,433 — — 33,433 Money market funds — 3,845 — — 3,845 Total debt and equity securities 58,734 37,278 — — 96,012 Total assets $ 58,734 $ 419,269 $ — $ — $ 478,003 Liabilities: Financial instruments $ — $ 4,129 $ — $ — $ 4,129 (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, 2022, 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 March 31, 2023, no allowance for credit losses was recorded for our available-for-sale debt securities. At March 31, 2023 and September 30, 2022, the amortized cost of our available-for-sale debt securities was $35.3 million and $34.1 million. At March 31, 2023, we maintained investments in bonds that have contractual maturity dates ranging from April 2023 through September 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 March 31, 2023 and September 30, 2022: March 31, 2023 September 30, 2022 (In thousands) Carrying Amount $ 6,560,000 $ 7,960,000 Fair Value $ 5,879,825 $ 6,918,843

Concentration of Credit Risk

Concentration of Credit Risk	6 Months Ended
	Mar. 31, 2023
Risks and Uncertainties [Abstract]
Concentration of Credit Risk	Concentration of Credit RiskInformation regarding our concentration of credit risk is disclosed in Note 17 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2022. During the six months ended March 31, 2023, there were no material changes in our concentration of credit risk.

Unaudited Financial Informati_2

Unaudited Financial Information (Policies)	6 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Regulatory assets and liabilities	Regulatory assets and liabilities 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.
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 7 to the unaudited condensed consolidated financial statements, when the impact is dilutive.
Fair Value Measurement	Fair Value MeasurementsWe 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, accounts receivable and accounts payable 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, 2022. During the six months ended March 31, 2023, there were no changes in these methods.

Unaudited Financial Informati_3

Unaudited Financial Information (Tables)	6 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Schedule of Regulatory Assets	Significant regulatory assets and liabilities as of March 31, 2023 and September 30, 2022 included the following: March 31, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 24,096 $ 31,122 Infrastructure mechanisms (1) 203,010 235,972 Winter Storm Uri incremental costs (2) 121,493 2,109,454 Deferred gas costs 49,156 119,742 Regulatory excess deferred taxes (3) 47,656 47,311 Recoverable loss on reacquired debt 3,322 3,406 Deferred pipeline record collection costs 51,967 36,898 Other 13,231 21,467 $ 513,931 $ 2,605,372 Regulatory liabilities: Regulatory excess deferred taxes (3) $ 466,496 $ 545,021 Regulatory cost of removal obligation 568,778 568,307 Deferred gas costs 97,407 28,834 Asset retirement obligation 5,737 5,737 APT annual adjustment mechanism 39,360 31,138 Pension and postretirement benefit costs 146,829 156,857 Other 30,703 23,013 $ 1,355,310 $ 1,358,907 (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) Includes extraordinary gas costs incurred during Winter Storm Uri and certain related carrying costs. See Note 8 to the unaudited condensed consolidated financial statements for further information. (3) 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 11 to the unaudited condensed consolidated financial statements for further information.
Schedule of Regulatory Liabilities	Significant regulatory assets and liabilities as of March 31, 2023 and September 30, 2022 included the following: March 31, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 24,096 $ 31,122 Infrastructure mechanisms (1) 203,010 235,972 Winter Storm Uri incremental costs (2) 121,493 2,109,454 Deferred gas costs 49,156 119,742 Regulatory excess deferred taxes (3) 47,656 47,311 Recoverable loss on reacquired debt 3,322 3,406 Deferred pipeline record collection costs 51,967 36,898 Other 13,231 21,467 $ 513,931 $ 2,605,372 Regulatory liabilities: Regulatory excess deferred taxes (3) $ 466,496 $ 545,021 Regulatory cost of removal obligation 568,778 568,307 Deferred gas costs 97,407 28,834 Asset retirement obligation 5,737 5,737 APT annual adjustment mechanism 39,360 31,138 Pension and postretirement benefit costs 146,829 156,857 Other 30,703 23,013 $ 1,355,310 $ 1,358,907 (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) Includes extraordinary gas costs incurred during Winter Storm Uri and certain related carrying costs. See Note 8 to the unaudited condensed consolidated financial statements for further information. (3) 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 11 to the unaudited condensed consolidated financial statements for further information.

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Mar. 31, 2023
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Income statements and capital expenditures for the three and six months ended March 31, 2023 and 2022 by segment are presented in the following tables: Three Months Ended March 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,499,437 $ 41,536 $ — $ 1,540,973 Intersegment revenues 773 142,888 (143,661) — Total operating revenues 1,500,210 184,424 (143,661) 1,540,973 Purchased gas cost 809,023 621 (143,433) 666,211 Operation and maintenance expense 151,353 43,591 (228) 194,716 Depreciation and amortization expense 106,310 42,007 — 148,317 Taxes, other than income 98,200 10,891 — 109,091 Operating income 335,324 87,314 — 422,638 Other non-operating income 7,465 9,941 — 17,406 Interest charges 21,420 15,950 — 37,370 Income before income taxes 321,369 81,305 — 402,674 Income tax expense 32,895 12,108 — 45,003 Net income $ 288,474 $ 69,197 $ — $ 357,671 Capital expenditures $ 424,989 $ 194,700 $ — $ 619,689 Three Months Ended March 31, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 1,609,667 $ 40,152 $ — $ 1,649,819 Intersegment revenues 879 123,595 (124,474) — Total operating revenues 1,610,546 163,747 (124,474) 1,649,819 Purchased gas cost 993,854 1,683 (124,159) 871,378 Operation and maintenance expense 121,541 42,126 (315) 163,352 Depreciation and amortization expense 96,612 36,762 — 133,374 Taxes, other than income 87,236 9,347 — 96,583 Operating income 311,303 73,829 — 385,132 Other non-operating income 549 4,664 — 5,213 Interest charges 15,157 13,771 — 28,928 Income before income taxes 296,695 64,722 — 361,417 Income tax expense 27,844 8,574 — 36,418 Net income $ 268,851 $ 56,148 $ — $ 324,999 Capital expenditures $ 362,468 $ 143,381 $ — $ 505,849 Six Months Ended March 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,939,130 $ 85,852 $ — $ 3,024,982 Intersegment revenues 1,506 285,201 (286,707) — Total operating revenues 2,940,636 371,053 (286,707) 3,024,982 Purchased gas cost 1,690,938 (237) (286,241) 1,404,460 Operation and maintenance expense 287,822 92,376 (466) 379,732 Depreciation and amortization expense 211,974 82,363 — 294,337 Taxes, other than income 182,822 19,807 — 202,629 Operating income 567,080 176,744 — 743,824 Other non-operating income 14,239 24,358 — 38,597 Interest charges 44,259 29,871 — 74,130 Income before income taxes 537,060 171,231 — 708,291 Income tax expense 54,118 24,642 — 78,760 Net income $ 482,942 $ 146,589 $ — $ 629,531 Capital expenditures $ 868,533 $ 546,816 $ — $ 1,415,349 Six Months Ended March 31, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,581,303 $ 81,302 $ — $ 2,662,605 Intersegment revenues 1,665 245,363 (247,028) — Total operating revenues 2,582,968 326,665 (247,028) 2,662,605 Purchased gas cost 1,490,653 (1,728) (246,384) 1,242,541 Operation and maintenance expense 244,825 78,281 (644) 322,462 Depreciation and amortization expense 189,409 71,821 — 261,230 Taxes, other than income 156,281 19,098 — 175,379 Operating income 501,800 159,193 — 660,993 Other non-operating income 2,465 11,450 — 13,915 Interest charges 23,705 25,074 — 48,779 Income before income taxes 480,560 145,569 — 626,129 Income tax expense 32,138 19,783 — 51,921 Net income $ 448,422 $ 125,786 $ — $ 574,208 Capital expenditures $ 799,850 $ 390,179 $ — $ 1,190,029 Balance sheet information at March 31, 2023 and September 30, 2022 by segment is presented in the following tables: March 31, 2023 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Net property, plant and equipment $ 13,495,410 $ 4,950,476 $ — $ 18,445,886 Total assets $ 20,565,390 $ 5,226,910 $ (4,480,439) $ 21,311,861 September 30, 2022 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Net property, plant and equipment $ 12,723,532 $ 4,516,707 $ — $ 17,240,239 Total assets $ 21,424,586 $ 4,797,206 $ (4,028,803) $ 22,192,989

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Mar. 31, 2023
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted earnings per share for the three and six months ended March 31, 2023 and 2022 are calculated as follows: Three Months Ended March 31 Six Months Ended March 31 2023 2022 2023 2022 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 357,671 $ 324,999 $ 629,531 $ 574,208 Less: Income allocated to participating securities 212 202 381 379 Income available to common shareholders $ 357,459 $ 324,797 $ 629,150 $ 573,829 Basic weighted average shares outstanding 143,941 136,834 142,881 135,259 Net income per share — Basic $ 2.48 $ 2.37 $ 4.40 $ 4.24 Diluted Earnings Per Share Income available to common shareholders $ 357,459 $ 324,797 $ 629,150 $ 573,829 Effect of dilutive shares — — — — Income available to common shareholders $ 357,459 $ 324,797 $ 629,150 $ 573,829 Basic weighted average shares outstanding 143,941 136,834 142,881 135,259 Dilutive shares 46 416 82 211 Diluted weighted average shares outstanding 143,987 137,250 142,963 135,470 Net income per share — Diluted $ 2.48 $ 2.37 $ 4.40 $ 4.24

Revenue and Accounts Receivab_2

Revenue and Accounts Receivable (Tables)	6 Months Ended
	Mar. 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 and six months ended March 31, 2023 and 2022. Three Months Ended March 31, 2023 Three Months Ended March 31, 2022 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 943,090 $ — $ 1,090,702 $ — Commercial 398,812 — 428,330 — Industrial 45,044 — 54,372 — Public authority and other 22,686 — 26,396 — Total gas sales revenues 1,409,632 — 1,599,800 — Transportation revenues 33,511 190,248 32,801 163,850 Miscellaneous revenues 2,662 1,152 2,680 2,284 Revenues from contracts with customers 1,445,805 191,400 1,635,281 166,134 Alternative revenue program revenues (1) 53,910 (6,976) (25,246) (2,387) Other revenues 495 — 511 — Total operating revenues $ 1,500,210 $ 184,424 $ 1,610,546 $ 163,747 Six Months Ended March 31, 2023 Six Months Ended March 31, 2022 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 1,896,141 $ — $ 1,666,543 $ — Commercial 787,479 — 679,091 — Industrial 104,259 — 103,053 — Public authority and other 45,512 — 41,588 — Total gas sales revenues 2,833,391 — 2,490,275 — Transportation revenues 65,673 385,500 60,670 327,709 Miscellaneous revenues 4,944 3,874 5,279 8,827 Revenues from contracts with customers 2,904,008 389,374 2,556,224 336,536 Alternative revenue program revenues (1) 35,588 (18,321) 25,740 (9,871) Other revenues 1,040 — 1,004 — Total operating revenues $ 2,940,636 $ 371,053 $ 2,582,968 $ 326,665 (1) In our distribution segment, we have weather-normalization adjustment mechanisms that serve to mitigate the effects of weather on our revenue. Additionally, APT has a regulatory mechanism that requires that APT shares with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a revenue benchmark.
Schedule of Allowance for Credit Loss Activity	Rollforwards of our allowance for uncollectible accounts for the three and six months ended March 31, 2023 and 2022 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 81 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. Three Months Ended March 31, 2023 (In thousands) Beginning balance, December 31, 2022 $ 47,613 Current period provisions 13,009 Write-offs charged against allowance (8,333) Recoveries of amounts previously written off 462 Ending balance, March 31, 2023 $ 52,751 Three Months Ended March 31, 2022 (In thousands) Beginning balance, December 31, 2021 $ 64,934 Current period provisions 5,705 Write-offs charged against allowance (9,029) Recoveries of amounts previously written off 603 Ending balance, March 31, 2022 $ 62,213 Six Months Ended March 31, 2023 (In thousands) Beginning balance, September 30, 2022 $ 49,993 Current period provisions 20,242 Write-offs charged against allowance (18,754) Recoveries of amounts previously written off 1,270 Ending balance, March 31, 2023 $ 52,751 Six Months Ended March 31, 2022 (In thousands) Beginning balance, September 30, 2021 $ 64,471 Current period provisions 12,075 Write-offs charged against allowance (15,458) Recoveries of amounts previously written off 1,125 Ending balance, March 31, 2022 $ 62,213

Debt (Tables)

Debt (Tables)	6 Months Ended
	Mar. 31, 2023
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt at March 31, 2023 and September 30, 2022 consisted of the following: March 31, 2023 September 30, 2022 (In thousands) Unsecured 0.625% Senior Notes, due March 2023 $ — $ 1,100,000 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 — 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 — Floating-rate Senior Notes, due March 2023 — 1,100,000 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 51,133 51,850 Total long-term debt 6,611,133 8,011,850 Less: Original issue discount on unsecured senior notes and debentures 6,271 3,704 Debt issuance cost 50,253 46,042 Current maturities of long-term debt 1,512 2,201,457 $ 6,553,097 $ 5,760,647

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	6 Months Ended
	Mar. 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 and six months ended March 31, 2023 and 2022. Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2022 140,896,598 $ 704 $ 5,838,118 $ 369,112 $ 3,211,157 $ 9,419,091 Net income — — — — 271,860 271,860 Other comprehensive income — — — 22,218 — 22,218 Cash dividends ($0.74 per share) — — — — (104,552) (104,552) Common stock issued: Public and other stock offerings 2,147,210 11 223,768 — — 223,779 Stock-based compensation plans 111,953 1 3,877 — — 3,878 Balance, December 31, 2022 143,155,761 716 6,065,763 391,330 3,378,465 9,836,274 Net income — — — — 357,671 357,671 Other comprehensive loss — — — (30,333) — (30,333) Cash dividends ($0.74 per share) — — — — (106,173) (106,173) Common stock issued: Public and other stock offerings 1,316,930 6 143,808 — — 143,814 Stock-based compensation plans 11,959 — 3,952 — — 3,952 Balance, March 31, 2023 144,484,650 $ 722 $ 6,213,523 $ 360,997 $ 3,629,963 $ 10,205,205 Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2021 132,419,754 $ 662 $ 5,023,751 $ 69,803 $ 2,812,673 $ 7,906,889 Net income — — — — 249,209 249,209 Other comprehensive loss — — — (45,947) — (45,947) Cash dividends ($0.68 per share) — — — — (90,411) (90,411) Common stock issued: Public and other stock offerings 2,730,115 13 265,848 — — 265,861 Stock-based compensation plans 275,212 2 3,942 — — 3,944 Balance, December 31, 2021 135,425,081 677 5,293,541 23,856 2,971,471 8,289,545 Net income — — — — 324,999 324,999 Other comprehensive income — — — 121,723 — 121,723 Cash dividends ($0.68 per share) — — — — (93,533) (93,533) Common stock issued: Public and other stock offerings 3,509,116 18 336,451 — — 336,469 Stock-based compensation plans 77,832 — 4,028 — — 4,028 Balance, March 31, 2022 139,012,029 $ 695 $ 5,634,020 $ 145,579 $ 3,202,937 $ 8,983,231
Schedule of Forward Sales Agreements	Additionally, we had $673.2 million in available proceeds from outstanding forward sale agreements, as detailed below. Maturity Shares Available Net Proceeds Available Forward Price September 29, 2023 1,157,238 $ 132,198 $ 114.24 December 29, 2023 919,898 105,843 $ 115.06 March 28, 2024 2,744,502 319,894 $ 116.56 June 28, 2024 927,939 108,491 $ 116.92 September 30, 2024 58,807 6,792 $ 115.49 Total 5,808,384 $ 673,218 $ 115.90
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, 2022 $ (495) $ 369,607 $ 369,112 Other comprehensive income (loss) before reclassifications 221 (7,276) (7,055) Amounts reclassified from accumulated other comprehensive income — (1,060) (1,060) Net current-period other comprehensive income (loss) 221 (8,336) (8,115) March 31, 2023 $ (274) $ 361,271 $ 360,997 Available- Interest Rate Total (In thousands) September 30, 2021 $ 47 $ 69,756 $ 69,803 Other comprehensive income (loss) before reclassifications (230) 74,518 74,288 Amounts reclassified from accumulated other comprehensive income — 1,488 1,488 Net current-period other comprehensive income (loss) (230) 76,006 75,776 March 31, 2022 $ (183) $ 145,762 $ 145,579

Interim Pension and Other Pos_2

Interim Pension and Other Postretirement Benefit Plan Information (Tables)	6 Months Ended
	Mar. 31, 2023
Retirement Benefits, Description [Abstract]
Schedule of Net Benefit Costs	The components of our net periodic pension cost for our pension and other postretirement benefit plans for the three and six months ended March 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. Three Months Ended March 31 Pension Benefits Other Benefits 2023 2022 2023 2022 (In thousands) Components of net periodic pension cost: Service cost $ 2,908 $ 4,324 $ 1,546 $ 2,558 Interest cost (1) 7,325 5,064 3,478 2,684 Expected return on assets (1) (7,278) (7,383) (2,804) (3,313) Amortization of prior service cost (credit) (1) (30) (58) (3,285) (3,308) Amortization of actuarial (gain) loss (1) 164 1,951 (1,863) — Net periodic pension cost $ 3,089 $ 3,898 $ (2,928) $ (1,379) Six Months Ended March 31 Pension Benefits Other Benefits 2023 2022 2023 2022 (In thousands) Components of net periodic pension cost: Service cost $ 5,816 $ 8,647 $ 3,091 $ 5,117 Interest cost (1) 14,650 10,127 6,955 5,367 Expected return on assets (1) (14,556) (14,766) (5,608) (6,625) Amortization of prior service cost (credit) (1) (61) (116) (6,571) (6,617) Amortization of actuarial (gain) loss (1) 329 3,902 (3,726) — Net periodic pension cost $ 6,178 $ 7,794 $ (5,859) $ (2,758) (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, 2022.

Financial Instruments (Tables)

Financial Instruments (Tables)	6 Months Ended
	Mar. 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 March 31, 2023. Planned Debt Issuance Date Amount Hedged (In thousands) Fiscal 2024 $ 600,000 Fiscal 2025 600,000 Fiscal 2026 300,000 $ 1,500,000
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 March 31, 2023 and September 30, 2022. The gross amounts of recognized assets and liabilities are netted within our unaudited condensed consolidated balance sheets to the extent that we have netting arrangements with our counterparties. However, as of March 31, 2023 and September 30, 2022, no gross amounts and no cash collateral were netted within our consolidated balance sheet. March 31, 2023 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Other current assets / $ 95,735 $ (272) Interest rate contracts Deferred charges and other assets / 250,232 — Total 345,967 (272) Not Designated As Hedges: Commodity contracts Other current assets / 1,974 (11,679) Total 1,974 (11,679) Gross / Net Financial Instruments $ 347,941 $ (11,951) September 30, 2022 Balance Sheet Location Assets Liabilities (In thousands) Designated As Hedges: Interest rate contracts Deferred charges and other assets / $ 355,075 $ — Total 355,075 — Not Designated As Hedges: Commodity contracts Other current assets / 26,207 (3,000) Commodity contracts Deferred charges and other assets / 709 (1,129) Total 26,916 (4,129) Gross / Net Financial Instruments $ 381,991 $ (4,129)
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)	The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and six months ended March 31, 2023 and 2022. Three Months Ended March 31 Six Months Ended March 31 2023 2022 2023 2022 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (29,937) $ 121,140 $ (7,276) $ 74,518 Recognition of (gains) losses in earnings due to settlements: Interest rate agreements (530) 744 (1,060) 1,488 Total other comprehensive income (loss) from hedging, net of tax $ (30,467) $ 121,884 $ (8,336) $ 76,006
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 $ 2,120 Thereafter 90,967 Total $ 93,087

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Mar. 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 March 31, 2023 and September 30, 2022. 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 March 31, 2023 (In thousands) Assets: Financial instruments $ — $ 347,941 $ — $ — $ 347,941 Debt and equity securities Registered investment companies 27,596 — — — 27,596 Bond mutual funds 33,326 — — — 33,326 Bonds (2) — 34,962 — — 34,962 Money market funds — 6,458 — — 6,458 Total debt and equity securities 60,922 41,420 — — 102,342 Total assets $ 60,922 $ 389,361 $ — $ — $ 450,283 Liabilities: Financial instruments $ — $ 11,951 $ — $ — $ 11,951 Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and September 30, 2022 (In thousands) Assets: Financial instruments $ — $ 381,991 $ — $ — $ 381,991 Debt and equity securities Registered investment companies 26,367 — — — 26,367 Bond mutual funds 32,367 — — — 32,367 Bonds (2) — 33,433 — — 33,433 Money market funds — 3,845 — — 3,845 Total debt and equity securities 58,734 37,278 — — 96,012 Total assets $ 58,734 $ 419,269 $ — $ — $ 478,003 Liabilities: Financial instruments $ — $ 4,129 $ — $ — $ 4,129 (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 March 31, 2023 and September 30, 2022: March 31, 2023 September 30, 2022 (In thousands) Carrying Amount $ 6,560,000 $ 7,960,000 Fair Value $ 5,879,825 $ 6,918,843

Nature of Business (Details)

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

Unaudited Financial Informati_4

Unaudited Financial Information - Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Regulatory Asset [Line Items]
Regulatory assets	$ 513,931	$ 2,605,372
Regulatory Liabilities [Line Items]
Regulatory liabilities	1,355,310	1,358,907
Regulatory excess deferred taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	466,496	545,021
Regulatory cost of removal obligation
Regulatory Liabilities [Line Items]
Regulatory liabilities	568,778	568,307
Deferred gas costs
Regulatory Liabilities [Line Items]
Regulatory liabilities	97,407	28,834
Asset retirement obligation
Regulatory Liabilities [Line Items]
Regulatory liabilities	5,737	5,737
APT annual adjustment mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities	39,360	31,138
Pension and postretirement benefit costs
Regulatory Liabilities [Line Items]
Regulatory liabilities	146,829	156,857
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	30,703	23,013
Pension and postretirement benefit costs
Regulatory Asset [Line Items]
Regulatory assets	24,096	31,122
Infrastructure mechanisms
Regulatory Asset [Line Items]
Regulatory assets	203,010	235,972
Winter Storm Uri incremental costs
Regulatory Asset [Line Items]
Regulatory assets	121,493	2,109,454
Deferred gas costs
Regulatory Asset [Line Items]
Regulatory assets	49,156	119,742
Regulatory excess deferred taxes
Regulatory Asset [Line Items]
Regulatory assets	47,656	47,311
Recoverable loss on reacquired debt
Regulatory Asset [Line Items]
Regulatory assets	3,322	3,406
Deferred pipeline record collection costs
Regulatory Asset [Line Items]
Regulatory assets	51,967	36,898
Other
Regulatory Asset [Line Items]
Regulatory assets	$ 13,231	$ 21,467

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023 USD ($) state	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2023 USD ($) state	Mar. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of states with service areas | state	8				8
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	$ 1,540,973		$ 1,649,819		$ 3,024,982	$ 2,662,605
Purchased gas cost	666,211		871,378		1,404,460	1,242,541
Operation and maintenance expense	194,716		163,352		379,732	322,462
Depreciation and amortization expense	148,317		133,374		294,337	261,230
Taxes, other than income	109,091		96,583		202,629	175,379
Operating income	422,638		385,132		743,824	660,993
Other non-operating income	17,406		5,213		38,597	13,915
Interest charges	37,370		28,928		74,130	48,779
Income before income taxes	402,674		361,417		708,291	626,129
Income tax expense	45,003		36,418		78,760	51,921
Net income	357,671	$ 271,860	324,999	$ 249,209	629,531	574,208
Capital expenditures	619,689		505,849		1,415,349	1,190,029
Segment Reporting Information, Balance Sheet [Abstract]
Net property, plant and equipment	18,445,886				18,445,886		$ 17,240,239
Total assets	21,311,861				21,311,861		22,192,989
Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	1,499,437		1,609,667		2,939,130	2,581,303
Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	41,536		40,152		85,852	81,302
Eliminations
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	(143,661)		(124,474)		(286,707)	(247,028)
Purchased gas cost	(143,433)		(124,159)		(286,241)	(246,384)
Operation and maintenance expense	(228)		(315)		(466)	(644)
Depreciation and amortization expense	0		0		0	0
Taxes, other than income	0		0		0	0
Operating income	0		0		0	0
Other non-operating income	0		0		0	0
Interest charges	0		0		0	0
Income before income taxes	0		0		0	0
Income tax expense	0		0		0	0
Net income	0		0		0	0
Capital expenditures	0		0		0	0
Segment Reporting Information, Balance Sheet [Abstract]
Net property, plant and equipment	0				0		0
Total assets	(4,480,439)				(4,480,439)		(4,028,803)
Eliminations | Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	773		879		1,506	1,665
Eliminations | Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	142,888		123,595		285,201	245,363
Operating Segments | Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	1,500,210		1,610,546		2,940,636	2,582,968
Purchased gas cost	809,023		993,854		1,690,938	1,490,653
Operation and maintenance expense	151,353		121,541		287,822	244,825
Depreciation and amortization expense	106,310		96,612		211,974	189,409
Taxes, other than income	98,200		87,236		182,822	156,281
Operating income	335,324		311,303		567,080	501,800
Other non-operating income	7,465		549		14,239	2,465
Interest charges	21,420		15,157		44,259	23,705
Income before income taxes	321,369		296,695		537,060	480,560
Income tax expense	32,895		27,844		54,118	32,138
Net income	288,474		268,851		482,942	448,422
Capital expenditures	424,989		362,468		868,533	799,850
Segment Reporting Information, Balance Sheet [Abstract]
Net property, plant and equipment	13,495,410				13,495,410		12,723,532
Total assets	20,565,390				20,565,390		21,424,586
Operating Segments | Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	184,424		163,747		371,053	326,665
Purchased gas cost	621		1,683		(237)	(1,728)
Operation and maintenance expense	43,591		42,126		92,376	78,281
Depreciation and amortization expense	42,007		36,762		82,363	71,821
Taxes, other than income	10,891		9,347		19,807	19,098
Operating income	87,314		73,829		176,744	159,193
Other non-operating income	9,941		4,664		24,358	11,450
Interest charges	15,950		13,771		29,871	25,074
Income before income taxes	81,305		64,722		171,231	145,569
Income tax expense	12,108		8,574		24,642	19,783
Net income	69,197		56,148		146,589	125,786
Capital expenditures	194,700		$ 143,381		546,816	$ 390,179
Segment Reporting Information, Balance Sheet [Abstract]
Net property, plant and equipment	4,950,476				4,950,476		4,516,707
Total assets	$ 5,226,910				$ 5,226,910		$ 4,797,206

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Mar. 31, 2022
Basic Earnings Per Share
Net income	$ 357,671	$ 271,860	$ 324,999	$ 249,209	$ 629,531	$ 574,208
Less: Income allocated to participating securities	212		202		381	379
Income available to common shareholders	$ 357,459		$ 324,797		$ 629,150	$ 573,829
Basic weighted average shares outstanding (in shares)	143,941		136,834		142,881	135,259
Net income per share - Basic (USD per share)	$ 2.48		$ 2.37		$ 4.40	$ 4.24
Diluted Earnings Per Share
Income available to common shareholders	$ 357,459		$ 324,797		$ 629,150	$ 573,829
Effect of dilutive shares	0		0		0	0
Income available to common shareholders	$ 357,459		$ 324,797		$ 629,150	$ 573,829
Basic weighted average shares outstanding (in shares)	143,941		136,834		142,881	135,259
Dilutive shares (in shares)	46		416		82	211
Diluted weighted average shares outstanding (in shares)	143,987		137,250		142,963	135,470
Net income per share - Diluted (USD per share)	$ 2.48		$ 2.37		$ 4.40	$ 4.24

Revenue and Accounts Receivab_3

Revenue and Accounts Receivable - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 1,540,973	$ 1,649,819	$ 3,024,982	$ 2,662,605
Distribution
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 1,499,437	$ 1,609,667	$ 2,939,130	$ 2,581,303
Regulatory mechanism threshold (in percent)	75%	75%	75%	75%
Pipeline and Storage
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 41,536	$ 40,152	$ 85,852	$ 81,302
Operating Segments | Distribution
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,445,805	1,635,281	2,904,008	2,556,224
Alternative revenue program revenues	53,910	(25,246)	35,588	25,740
Other revenues	495	511	1,040	1,004
Total operating revenues	1,500,210	1,610,546	2,940,636	2,582,968
Operating Segments | Distribution | Gas sales revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,409,632	1,599,800	2,833,391	2,490,275
Operating Segments | Distribution | Gas sales revenues | Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	943,090	1,090,702	1,896,141	1,666,543
Operating Segments | Distribution | Gas sales revenues | Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	398,812	428,330	787,479	679,091
Operating Segments | Distribution | Gas sales revenues | Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	45,044	54,372	104,259	103,053
Operating Segments | Distribution | Gas sales revenues | Public authority and other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	22,686	26,396	45,512	41,588
Operating Segments | Distribution | Transportation revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	33,511	32,801	65,673	60,670
Operating Segments | Distribution | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,662	2,680	4,944	5,279
Operating Segments | Pipeline and Storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	191,400	166,134	389,374	336,536
Alternative revenue program revenues	(6,976)	(2,387)	(18,321)	(9,871)
Other revenues	0	0	0	0
Total operating revenues	184,424	163,747	371,053	326,665
Operating Segments | Pipeline and Storage | Gas sales revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Operating Segments | Pipeline and Storage | Gas sales revenues | Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Operating Segments | Pipeline and Storage | Gas sales revenues | Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Operating Segments | Pipeline and Storage | Gas sales revenues | Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	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	0	0
Operating Segments | Pipeline and Storage | Transportation revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	190,248	163,850	385,500	327,709
Operating Segments | Pipeline and Storage | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 1,152	$ 2,284	$ 3,874	$ 8,827

Revenue and Accounts Receivab_4

Revenue and Accounts Receivable - Allowance for Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Revenue from Contract with Customer [Abstract]
Percent of customers excluded	81%	81%	81%	81%
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 47,613	$ 64,934	$ 49,993	$ 64,471
Current period provisions	13,009	5,705	20,242	12,075
Write-offs charged against allowance	(8,333)	(9,029)	(18,754)	(15,458)
Recoveries of amounts previously written off	462	603	1,270	1,125
Ending balance	$ 52,751	$ 62,213	$ 52,751	$ 62,213

Debt - Schedule of Long-term De

Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Long-term debt	$ 6,560,000	$ 7,960,000
Finance lease obligations	51,133	51,850
Total long-term debt	6,611,133	8,011,850
Less:
Original issue discount on unsecured senior notes and debentures	6,271	3,704
Debt issuance cost	50,253	46,042
Current maturities of long-term debt	1,512	2,201,457
Long-term debt	$ 6,553,097	5,760,647
Unsecured 0.625% Senior Notes, due March 2023
Debt Instrument [Line Items]
Interest rate	0.625%
Long-term debt	$ 0	1,100,000
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	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	0
Floating-rate Senior Notes, due March 2023
Debt Instrument [Line Items]
Long-term debt	$ 0	1,100,000
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)				6 Months Ended
	Mar. 09, 2023 USD ($)	Mar. 03, 2023 USD ($)	Oct. 03, 2022 USD ($)	Mar. 31, 2023 USD ($) creditFacility	Mar. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Mar. 31, 2021 USD ($)
Line Of Credit Facility [Line Items]
Proceeds from issuance of long-term debt				$ 797,258,000	$ 798,802,000
Repayment of long-term debt				$ 2,200,000,000	$ 200,000,000
Maximum debt-to-total-capitalization ratio				70%
Debt-to-total-capitalization ratio				0.40
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity				$ 2,500,000,000
Number of credit facilities | creditFacility				4
Minimum
Line Of Credit Facility [Line Items]
Outstanding indebtedness				$ 15,000,000
Maximum
Line Of Credit Facility [Line Items]
Outstanding indebtedness				100,000,000
Senior Notes
Line Of Credit Facility [Line Items]
Debt instrument, face amount							$ 2,200,000,000
Repayment of long-term debt		$ 2,200,000,000
Unsecured Debt | Line of Credit
Line Of Credit Facility [Line Items]
Repayment of long-term debt	$ 1,100,000,000
Unsecured Senior Notes Due October 2052 | Senior Notes
Line Of Credit Facility [Line Items]
Debt instrument, face amount			$ 500,000,000
Interest rate			5.75%
Effective interest rate			4.50%
Unsecured Senior Notes Due October 2032 | Senior Notes
Line Of Credit Facility [Line Items]
Debt instrument, face amount			$ 300,000,000
Interest rate			5.45%
Effective interest rate			5.57%
Unsecured Senior Notes Due Octpber 2032 and Unsecured Senior Notes Due October 2052 | Senior Notes
Line Of Credit Facility [Line Items]
Proceeds from issuance of long-term debt			$ 789,400,000
Five Year Unsecured Revolving Credit Agreement
Line Of Credit Facility [Line Items]
Outstanding commercial paper				0		$ 185,000,000
Five Year Unsecured Revolving Credit Agreement | Commercial Paper
Line Of Credit Facility [Line Items]
Maximum borrowing capacity				$ 1,500,000,000
Debt agreement term				5 years
Accordion feature				$ 250,000,000
Maximum borrowing capacity post accordion feature				$ 1,750,000,000
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%
$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 | Minimum | Revolving Credit Facility | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread				0%
$900 Million Revolving Credit Facility | Minimum | Revolving Credit Facility | SOFR
Line Of Credit Facility [Line Items]
Interest rate spread				0.75%
$900 Million Revolving Credit Facility | Maximum | Revolving Credit Facility | Base Rate
Line Of Credit Facility [Line Items]
Interest rate spread				0.25%
$900 Million Revolving Credit Facility | Maximum | Revolving Credit Facility | 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
Unsecured Senior Term Loan Due 2023 | Unsecured Debt | Line of Credit
Line Of Credit Facility [Line Items]
Debt instrument, face amount		$ 2,020,000,000
Floating Rate Senior Notes | Unsecured Debt | Line of Credit
Line Of Credit Facility [Line Items]
Repayment of long-term debt	$ 1,100,000,000

Shareholders' Equity - Componen

Shareholders' Equity - Components of Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Mar. 31, 2022
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)		140,896,598			140,896,598
Shareholders' equity, beginning balance	$ 9,836,274	$ 9,419,091	$ 8,289,545	$ 7,906,889	$ 9,419,091	$ 7,906,889
Net income	357,671	271,860	324,999	249,209	629,531	574,208
Other comprehensive income (loss)	(30,333)	22,218	121,723	(45,947)	$ (8,115)	75,776
Cash dividends	(106,173)	(104,552)	(93,533)	(90,411)
Public and other stock offerings	143,814	223,779	336,469	265,861
Stock-based compensation plans	$ 3,952	3,878	4,028	3,944
Common stock outstanding, ending balance (in shares)	144,484,650				144,484,650
Shareholders' equity, ending balance	$ 10,205,205	$ 9,836,274	$ 8,983,231	$ 8,289,545	$ 10,205,205	$ 8,983,231
Cash dividends per share (USD per share)	$ 0.74	$ 0.74	$ 0.68	$ 0.68	$ 1.48	$ 1.36
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	143,155,761	140,896,598	135,425,081	132,419,754	140,896,598	132,419,754
Shareholders' equity, beginning balance	$ 716	$ 704	$ 677	$ 662	$ 704	$ 662
Public and other stock offerings (in shares)	1,316,930	2,147,210	3,509,116	2,730,115
Public and other stock offerings	$ 6	$ 11	$ 18	$ 13
Stock-based compensation plans (in shares)	11,959	111,953	77,832	275,212
Stock-based compensation plans		$ 1		$ 2
Common stock outstanding, ending balance (in shares)	144,484,650	143,155,761	139,012,029	135,425,081	144,484,650	139,012,029
Shareholders' equity, ending balance	$ 722	$ 716	$ 695	$ 677	$ 722	$ 695
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	6,065,763	5,838,118	5,293,541	5,023,751	5,838,118	5,023,751
Public and other stock offerings	143,808	223,768	336,451	265,848
Stock-based compensation plans	3,952	3,877	4,028	3,942
Shareholders' equity, ending balance	6,213,523	6,065,763	5,634,020	5,293,541	6,213,523	5,634,020
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	391,330	369,112	23,856	69,803	369,112	69,803
Other comprehensive income (loss)	(30,333)	22,218	121,723	(45,947)
Shareholders' equity, ending balance	360,997	391,330	145,579	23,856	360,997	145,579
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	3,378,465	3,211,157	2,971,471	2,812,673	3,211,157	2,812,673
Net income	357,671	271,860	324,999	249,209
Cash dividends	(106,173)	(104,552)	(93,533)	(90,411)
Shareholders' equity, ending balance	$ 3,629,963	$ 3,378,465	$ 3,202,937	$ 2,971,471	$ 3,629,963	$ 3,202,937

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details) - USD ($)	6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Class of Stock [Line Items]
Net proceeds available	$ 673,218,000
Net proceeds from equity issuances	359,683,000	$ 594,320,000
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	4,000,000,000
At-The-Market
Class of Stock [Line Items]
Equity authorized	$ 1,000,000,000
Forward sales equity agreement (in shares)	2,177,143
Net proceeds available	$ 257,000,000
Stock issued during period, new issues (in shares)	3,394,919
Net proceeds from equity issuances	$ 359,700,000
Equity available for issuance	$ 1,000,000,000

Shareholders' Equity - Forward

Shareholders' Equity - Forward Sales Agreement (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Mar. 31, 2023 USD ($) $ / shares shares
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	5,808,384
Net proceeds available | $	$ 673,218
Forward price (USD per share) | $ / shares	$ 115.90
Forward Sales Equity Agreement Maturing Quarter Ended September 29, 2023
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	1,157,238
Net proceeds available | $	$ 132,198
Forward price (USD per share) | $ / shares	$ 114.24
Forward Sales Equity Agreement Maturing Quarter Ended December 29, 2023
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	919,898
Net proceeds available | $	$ 105,843
Forward price (USD per share) | $ / shares	$ 115.06
Forward Sales Equity Agreement Maturing Quarter Ended March 28, 2024
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	2,744,502
Net proceeds available | $	$ 319,894
Forward price (USD per share) | $ / shares	$ 116.56
Forward Sales Equity Agreement Maturing Quarter Ended June 28, 2024
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	927,939
Net proceeds available | $	$ 108,491
Forward price (USD per share) | $ / shares	$ 116.92
Forward Sales Equity Agreement Maturing Quarter Ended September 30 2024
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares available (in shares) | shares	58,807
Net proceeds available | $	$ 6,792
Forward price (USD per share) | $ / shares	$ 115.49

Shareholders' Equity - Schedule

Shareholders' Equity - Schedule of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Mar. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	$ 9,836,274	$ 9,419,091	$ 8,289,545	$ 7,906,889	$ 9,419,091	$ 7,906,889
Other comprehensive income (loss) before reclassifications					(7,055)	74,288
Amounts reclassified from accumulated other comprehensive income					(1,060)	1,488
Net current-period other comprehensive income (loss)	(30,333)	22,218	121,723	(45,947)	(8,115)	75,776
Shareholders' equity, ending balance	10,205,205	9,836,274	8,983,231	8,289,545	10,205,205	8,983,231
Available- for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance		(495)		47	(495)	47
Other comprehensive income (loss) before reclassifications					221	(230)
Amounts reclassified from accumulated other comprehensive income					0	0
Net current-period other comprehensive income (loss)					221	(230)
Shareholders' equity, ending balance	(274)		(183)		(274)	(183)
Interest Rate Agreement Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance		369,607		69,756	369,607	69,756
Other comprehensive income (loss) before reclassifications					(7,276)	74,518
Amounts reclassified from accumulated other comprehensive income					(1,060)	1,488
Net current-period other comprehensive income (loss)					(8,336)	76,006
Shareholders' equity, ending balance	361,271		145,762		361,271	145,762
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	391,330	369,112	23,856	69,803	369,112	69,803
Net current-period other comprehensive income (loss)	(30,333)	22,218	121,723	(45,947)
Shareholders' equity, ending balance	$ 360,997	$ 391,330	$ 145,579	$ 23,856	$ 360,997	$ 145,579

Winter Storm Uri (Details)

Winter Storm Uri (Details) - USD ($) $ in Thousands					1 Months Ended	6 Months Ended		7 Months Ended
	Mar. 23, 2023	Mar. 09, 2023	Mar. 03, 2023	Oct. 25, 2022	Feb. 28, 2021	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Sep. 30, 2022	Mar. 31, 2021
Unusual or Infrequent Item, or Both [Line Items]
Aggregate natural gas purchases					$ 2,300,000
Repayment of senior notes						$ 2,200,000	$ 200,000
Regulatory assets						513,931		$ 513,931	$ 2,605,372
Winter Storm Uri incremental costs
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets						121,493		121,493	$ 2,109,454
Winter Storm Uri incremental costs | Winter Storm Uri | Kansas
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets						$ 89,100		89,100
Winter Storm Uri incremental costs | Winter Storm Uri | Texas
Unusual or Infrequent Item, or Both [Line Items]
Regulatory asset, deferred costs								$ 32,400
Extraordinary Gas Cost | Winter Storm Uri | Kansas
Unusual or Infrequent Item, or Both [Line Items]
Regulatory asset, authorized				$ 118,500
Regulatory asset, amortization period				12 years
Extraordinary Gas Cost | Winter Storm Uri | Texas
Unusual or Infrequent Item, or Both [Line Items]
Regulatory asset, authorized	$ 3,500,000
Proceeds from customer rate relief bonds	2,020,000
Regulatory asset, relieved	$ 2,020,000
Extraordinary Gas Cost | Winter Storm Uri | Texas | Minimum
Unusual or Infrequent Item, or Both [Line Items]
Regulatory asset, maturity period	12 years
Extraordinary Gas Cost | Winter Storm Uri | Texas | Maximum
Unusual or Infrequent Item, or Both [Line Items]
Regulatory asset, maturity period	18 years
Senior Notes
Unusual or Infrequent Item, or Both [Line Items]
Debt instrument, face amount										$ 2,200,000
Repayment of senior notes			$ 2,200,000
Unsecured Debt | Line of Credit
Unusual or Infrequent Item, or Both [Line Items]
Repayment of senior notes		$ 1,100,000
Unsecured Senior Term Loan Due 2023 | Unsecured Debt | Line of Credit
Unusual or Infrequent Item, or Both [Line Items]
Debt instrument, face amount			$ 2,020,000

Interim Pension and Other Pos_3

Interim Pension and Other Postretirement Benefit Plan Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Contribution to postretirement medical plans			$ 6,200
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,908	$ 4,324	5,816	$ 8,647
Interest cost	7,325	5,064	14,650	10,127
Expected return on assets	(7,278)	(7,383)	(14,556)	(14,766)
Amortization of prior service cost (credit)	(30)	(58)	(61)	(116)
Amortization of actuarial (gain) loss	164	1,951	329	3,902
Net periodic pension cost	3,089	3,898	6,178	7,794
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,546	2,558	3,091	5,117
Interest cost	3,478	2,684	6,955	5,367
Expected return on assets	(2,804)	(3,313)	(5,608)	(6,625)
Amortization of prior service cost (credit)	(3,285)	(3,308)	(6,571)	(6,617)
Amortization of actuarial (gain) loss	(1,863)	0	(3,726)	0
Net periodic pension cost	(2,928)	$ (1,379)	(5,859)	$ (2,758)
Other Benefits | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions	15,000		15,000
Other Benefits | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions	$ 25,000		$ 25,000

Commitments and Contingencies (

Commitments and Contingencies (Details) - Supply Commitment	6 Months Ended
	Mar. 31, 2023 $ / Mcf MMcf
Long-term Purchase Commitment [Line Items]
Contract term	1 year
Purchase commitment volume	7,300
Weighted Average
Long-term Purchase Commitment [Line Items]
Fixed price contracts (USD per Mcf) | $ / Mcf	2.64
Short-term Contract with Customer
Long-term Purchase Commitment [Line Items]
Contract term	1 year
Purchase commitment volume	81,200
Long-term Contract with Customer Within Two To Three Years
Long-term Purchase Commitment [Line Items]
Purchase commitment volume	109,200
Long-term Contract with Customer Within Two To Three Years | Minimum
Long-term Purchase Commitment [Line Items]
Contract term	2 years
Long-term Contract with Customer Within Two To Three Years | Maximum
Long-term Purchase Commitment [Line Items]
Contract term	3 years
Long-term Contract with Customer Beyond Three Years
Long-term Purchase Commitment [Line Items]
Contract term	3 years
Purchase commitment volume	3,100

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Income Tax Contingency [Line Items]
Effective income tax rate	11.20%	10.10%	11.10%	8.30%
Regulatory liabilities	$ 1,355,310		$ 1,355,310		$ 1,358,907
Regulatory excess deferred taxes
Income Tax Contingency [Line Items]
Deferred tax liabilities, net	418,900		418,900
Regulatory liabilities	466,496		466,496		545,021
Regulatory excess deferred taxes | Other Current Liabilities
Income Tax Contingency [Line Items]
Deferred tax liabilities, net	151,400		151,400		$ 159,800
Regulatory excess deferred taxes, to be returned, tranche one
Income Tax Contingency [Line Items]
Deferred tax liabilities, net	332,200		$ 332,200
Regulatory excess deferred taxes, to be returned, tranche one | Minimum
Income Tax Contingency [Line Items]
Return basis, term			35 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	71,600		$ 71,600
Regulatory excess deferred taxes, to be returned, tranche two | Minimum
Income Tax Contingency [Line Items]
Return basis, term			15 years
Regulatory excess deferred taxes, to be returned, tranche two | Maximum
Income Tax Contingency [Line Items]
Return basis, term			69 years
Regulatory excess deferred taxes, to be returned, tranche three
Income Tax Contingency [Line Items]
Deferred tax liabilities, net	$ 15,100		$ 15,100

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2023 USD ($) MMcf	Mar. 31, 2022 USD ($)	Apr. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Mar. 31, 2021 USD ($)
Derivative [Line Items]
Energy measure | MMcf			4,123
Contract netting	$ 0		$ 0			$ 0
Cash collateral	0		0			$ 0
Net (gain) loss on settled interest rate agreements	(700,000)	$ 1,000,000	(1,400,000)	$ 1,900,000
Net realized gains in AOCI	93,100,000		93,100,000
Senior Notes
Derivative [Line Items]
Debt instrument, face amount							$ 2,200,000,000
Forward Interest Rate Swap | Senior Notes
Derivative [Line Items]
Debt instrument, face amount	$ 150,000,000		$ 150,000,000
Forward Interest Rate Swap | Senior Notes | Subsequent Event
Derivative [Line Items]
Debt instrument, face amount					$ 100,000,000
Gas Purchases | Not Designated As Hedges: | Commodity contracts
Derivative [Line Items]
Hedging percent	32%		32%
Energy measure | MMcf			17,700
Minimum | Gas Purchases | Not Designated As Hedges: | Commodity contracts
Derivative [Line Items]
Hedging percent	25%		25%
Maximum | Gas Purchases | Not Designated As Hedges: | Commodity contracts
Derivative [Line Items]
Hedging percent	50%		50%

Financial Instruments - Schedul

Financial Instruments - Schedule of Interest Rate Risk Management Activities (Details) - Cash Flow Hedging - Designated As Hedges: $ in Thousands	Mar. 31, 2023 USD ($)
Forward Interest Rate Swap
Derivative [Line Items]
Derivative notional amount	$ 1,500,000
Forward Interest Rate Swap, Planned Issued Fiscal 2024
Derivative [Line Items]
Derivative notional amount	600,000
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	Mar. 31, 2023	Sep. 30, 2022
Derivatives Fair Value [Line Items]
Net financial instruments, assets	$ 347,941	$ 381,991
Net financial instruments, liabilities	(11,951)	(4,129)
Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	345,967	355,075
Gross financial instruments, liabilities	(272)	0
Designated As Hedges: | Other current assets | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	95,735
Designated As Hedges: | Other current liabilities | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, liabilities	(272)
Designated As Hedges: | Deferred charges and other assets | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	250,232	355,075
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	1,974	26,916
Gross financial instruments, liabilities	(11,679)	(4,129)
Not Designated As Hedges: | Other current assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets	1,974	26,207
Not Designated As Hedges: | Other current liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, liabilities	$ (11,679)	(3,000)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, assets		709
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross financial instruments, liabilities		$ (1,129)

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		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Increase (decrease) in fair value:
Interest rate agreements	$ (29,937)	$ 121,140	$ (7,276)	$ 74,518
Recognition of (gains) losses in earnings due to settlements:
Interest rate agreements	(530)	744	(1,060)	1,488
Total other comprehensive income (loss) from hedging, net of tax	$ (30,467)	$ 121,884	$ (8,336)	$ 76,006

Financial Instruments - Sched_4

Financial Instruments - Schedule Of Expected Deferred Gains (Losses) Recognition (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2023 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Next twelve months	$ 2,120
Thereafter	90,967
Total	$ 93,087

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial instruments net assets	$ 347,941	$ 381,991
Debt and equity securities	102,342	96,012
Total assets	450,283	478,003
Financial instruments net liability	11,951	4,129
Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	27,596	26,367
Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	33,326	32,367
Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	34,962	33,433
Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	6,458	3,845
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	60,922	58,734
Total assets	60,922	58,734
Financial instruments gross liability	0	0
Quoted Prices in Active Markets (Level 1) | Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	27,596	26,367
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	33,326	32,367
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	347,941	381,991
Debt and equity securities	41,420	37,278
Total assets	389,361	419,269
Financial instruments gross liability	11,951	4,129
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	34,962	33,433
Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity securities	6,458	3,845
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 ($)	Mar. 31, 2023	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Allowance for credit losses	$ 0
Cost basis	$ 35,300,000	$ 34,100,000

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Debt Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Carrying Amount	$ 6,560,000	$ 7,960,000
Fair Value	$ 5,879,825	$ 6,918,843