Atmos Energy (ATO) 10-Q 4 Aug 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Jun. 30, 2021	Jul. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
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)		130,790,813
Entity Central Index Key	0000731802
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
ASSETS
Property, plant and equipment	$ 17,265,383	$ 15,957,221
Less accumulated depreciation and amortization	2,787,634	2,601,874
Net property, plant and equipment	14,477,749	13,355,347
Current assets
Cash and cash equivalents	524,621	20,808
Accounts receivable, net (See Note 5)	291,122	230,595
Gas stored underground	99,469	111,950
Other current assets	200,154	107,905
Total current assets	1,115,366	471,258
Goodwill	731,257	731,257
Deferred charges and other assets (See Note 8)	2,991,063	801,170
Total assets	19,315,435	15,359,032
Shareholders’ equity
Common stock, no par value (stated at $0.005 per share); 200,000,000 shares authorized; issued and outstanding: June 30, 2021 — 130,787,039 shares; September 30, 2020 — 125,882,477 shares	654	629
Additional paid-in capital	4,865,268	4,377,149
Accumulated other comprehensive income (loss)	61,239	(57,589)
Retained earnings	2,846,597	2,471,014
Shareholders’ equity	7,773,758	6,791,203
Long-term debt	7,128,505	4,531,779
Total capitalization	14,902,263	11,322,982
Current liabilities
Accounts payable and accrued liabilities	280,352	235,775
Other current liabilities	581,722	546,461
Current maturities of long-term debt	200,442	165
Total current liabilities	1,062,516	782,401
Deferred income taxes	1,667,784	1,456,569
Regulatory excess deferred taxes	587,680	697,764
Regulatory cost of removal obligation	464,536	457,188
Deferred credits and other liabilities	630,656	642,128
Total capitalization and liabilities	$ 19,315,435	$ 15,359,032

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2021	Sep. 30, 2020
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)	130,787,039	125,882,477
Common stock outstanding (in shares)	130,787,039	125,882,477

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating revenues	$ 605,553	$ 492,995	$ 2,839,106	$ 2,346,223
Purchased gas cost	86,870	26,072	948,939	640,823
Operation and maintenance expense	184,470	149,460	479,488	449,529
Depreciation and amortization expense	119,348	107,104	353,269	318,082
Taxes, other than income	81,475	71,324	243,376	214,535
Operating income	133,390	139,035	814,034	723,254
Other non-operating income	5,887	7,235	14,793	9,133
Interest charges	20,962	19,580	69,068	68,980
Income before income taxes	118,315	126,690	759,759	663,407
Income tax expense	15,904	8,899	142,916	127,297
Net income	$ 102,411	$ 117,791	$ 616,843	$ 536,110
Basic net income per share (USD per share)	$ 0.78	$ 0.96	$ 4.77	$ 4.38
Diluted net income per share (USD per share)	0.78	0.96	4.77	4.37
Cash dividends per share (USD per share)	$ 0.625	$ 0.575	$ 1.875	$ 1.725
Basic weighted average shares outstanding (in shares)	131,358	123,026	129,185	122,352
Diluted weighted average shares outstanding (in shares)	131,486	123,032	129,229	122,463
Other comprehensive income (loss), net of tax
Net unrealized holding gains (losses) on available-for-sale securities, net of tax of $(11) and $96	$ (36)	$ 364	$ (165)	$ 200
Cash flow hedges:
Amortization and unrealized loss on interest rate agreements, net of tax of $(22,890) and $(1,115)	(79,196)	(4,450)	118,993	(2,344)
Total other comprehensive income (loss)	(79,232)	(4,086)	118,828	(2,144)
Total comprehensive income	23,179	113,705	735,671	533,966
Distribution segment
Operating revenues	557,931	434,650	2,715,644	2,194,786
Pipeline and storage segment
Operating revenues	47,622	58,345	123,462	151,437
Operating Segments | Distribution segment
Operating revenues	558,750	435,308	2,718,074	2,196,817
Purchased gas cost	202,050	126,093	1,304,269	942,586
Operation and maintenance expense	130,454	107,537	363,246	337,740
Depreciation and amortization expense	86,099	77,187	254,636	229,526
Taxes, other than income	72,024	61,980	214,991	190,636
Operating income	68,123	62,511	580,932	496,329
Other non-operating income	1,060	5,167	1,135	1,930
Income before income taxes	60,643	59,709	548,798	463,131
Income tax expense	7,354	810	109,481	87,411
Net income	53,289	58,899	439,317	375,720
Operating Segments | Pipeline and storage segment
Operating revenues	162,987	158,008	476,868	452,421
Purchased gas cost	691	(11)	(440)	290
Operation and maintenance expense	54,329	42,234	117,188	112,751
Depreciation and amortization expense	33,249	29,917	98,633	88,556
Taxes, other than income	9,451	9,344	28,385	23,899
Operating income	65,267	76,524	233,102	226,925
Other non-operating income	4,827	2,068	13,658	7,203
Income before income taxes	57,672	66,981	210,961	200,276
Income tax expense	8,550	8,089	33,435	39,886
Net income	49,122	58,892	177,526	160,390
Eliminations
Operating revenues	(116,184)	(100,321)	(355,836)	(303,015)
Purchased gas cost	(115,871)	(100,010)	(354,890)	(302,053)
Operation and maintenance expense	(313)	(311)	(946)	(962)
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
Income before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Net income	0	0	0	0
Eliminations | Distribution segment
Operating revenues	819	658	2,430	2,031
Eliminations | Pipeline and storage segment
Operating revenues	115,365	99,663	353,406	300,984
Purchased gas cost
Purchased gas cost	86,870	26,072	948,939	640,823
Purchased gas cost | Operating Segments | Distribution segment
Purchased gas cost	202,050	126,093	1,304,269	942,586
Purchased gas cost | Operating Segments | Pipeline and storage segment
Purchased gas cost	691	(11)	(440)	290
Purchased gas cost | Eliminations
Purchased gas cost	$ (115,871)	$ (100,010)	$ (354,890)	$ (302,053)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Net unrealized holding gains (losses) on available-for-sale securities, tax	$ (11)	$ 96	$ (48)	$ 47
Amortization and unrealized gain (loss) on interest rate agreements, tax	$ (22,890)	$ (1,115)	$ 34,392	$ (492)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash Flows From Operating Activities
Net income	$ 616,843	$ 536,110
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization expense	353,269	318,082
Deferred income taxes	144,195	137,996
One-time income tax benefit	0	(20,962)
Other	378	5,935
Net assets / liabilities from risk management activities	(99)	1,295
Net change in Winter Storm Uri regulatory asset (See Note 8)	(2,088,536)	0
Net change in other operating assets and liabilities	(184,517)	(82,970)
Net cash provided by (used in) operating activities	(1,158,467)	895,486
Cash Flows From Investing Activities
Capital expenditures	(1,357,960)	(1,405,673)
Debt and equity securities activities, net	(2,363)	(692)
Other, net	8,006	6,098
Net cash used in investing activities	(1,352,317)	(1,400,267)
Cash Flows From Financing Activities
Net decrease in short-term debt	0	(464,915)
Net proceeds from equity offering	460,678	358,047
Issuance of common stock through stock purchase and employee retirement plans	12,121	14,125
Proceeds from issuance of long-term debt	2,797,346	999,450
Cash dividends paid	(241,260)	(210,674)
Debt issuance costs	(14,288)	(7,738)
Net cash provided by financing activities	3,014,597	688,295
Net increase in cash and cash equivalents	503,813	183,514
Cash and cash equivalents at beginning of period	20,808	24,550
Cash and cash equivalents at end of period	$ 524,621	$ 208,064

Nature of Business

Nature of Business	9 Months Ended
	Jun. 30, 2021
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 three million residential, commercial, public authority and industrial customers through our six regulated distribution divisions, which at June 30, 2021, 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	9 Months Ended
	Jun. 30, 2021
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, aside from accounting policy changes noted below, 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, 2020. 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, 2020. Because of seasonal and other factors, the results of operations for the nine-month period ended June 30, 2021 are not indicative of our results of operations for the full 2021 fiscal year, which ends September 30, 2021. Except as described in Note 8, Note 10 and Note 11 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 Except as noted below, related to the change in policies as a result of our adoption of new accounting standards, 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, 2020. During the second quarter of fiscal 2021, we completed our goodwill impairment assessment. Based on the assessment performed, we determined that our goodwill was not impaired. Accounting pronouncements adopted in fiscal 2021 Effective October 1, 2020, we adopted new accounting guidance that requires credit losses on most financial assets measured at amortized cost and certain other instruments to be measured using an expected credit loss model. Under this model, we estimate credit losses over the entire contractual term of the instrument from the date of initial recognition of that instrument. The new guidance also introduces a new impairment recognition model for available-for-sale debt securities that will require credit losses to be recorded through an allowance account. We adopted the new guidance using a modified retrospective method. The adoption of this standard did not have a material impact on our financial position, results of operations and cash flows and no adjustments were made to October 1, 2020 opening balances as a result of this adoption. As required under the modified retrospective method of adoption, results for the reporting period beginning after October 1, 2020 are presented under Accounting Standards Codification (ASC) 326, while prior period amounts are not adjusted. See Notes 5 and 12 to the unaudited condensed consolidated financial statements for further discussion of implementation of the standard. Accounting pronouncements that will be effective after fiscal 2021 In March 2020, the Financial Accounting Standards Board (FASB) issued optional guidance which will ease the potential burden in accounting for or recognizing the effects of reference rate reform on financial reporting. The amendments provide optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions affected by the cessation of the London Interbank Offered Rate (LIBOR). The amendments can be elected immediately, as of March 12, 2020, through December 31, 2022. We are currently evaluating if we will apply the optional guidance as we assess the impact of the cessation of LIBOR on our current contracts and hedging relationships and the potential impact on our financial position, results of operations and cash flows. 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 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 June 30, 2021 and September 30, 2020 included the following: June 30, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 135,411 $ 149,089 Infrastructure mechanisms (1) 222,263 183,943 Winter Storm Uri incremental costs (2) 2,093,779 — Deferred gas costs 27,593 40,593 Regulatory excess deferred taxes 8,838 — Recoverable loss on reacquired debt 3,893 4,894 Deferred pipeline record collection costs 31,283 29,839 Other 3,952 6,283 $ 2,527,012 $ 414,641 Regulatory liabilities: Regulatory excess deferred taxes $ 694,018 $ 718,651 Regulatory cost of removal obligation 536,317 531,096 Deferred gas costs 55,572 19,985 Asset retirement obligation 20,348 20,348 APT annual adjustment mechanism 37,358 57,379 Other 19,371 19,554 $ 1,362,984 $ 1,367,013 (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 related carrying costs. See Note 8 to the unaudited condensed consolidated financial statements for further information. This amount is recorded within deferred charges and other assets on the condensed consolidated balance sheet as of June 30, 2021. 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. As of June 30, 2021 and September 30, 2020, $106.3 million and $20.9 million is recorded in other current liabilities. This amount has increased during fiscal 2021 due to regulatory approvals received during the fiscal year that shortened the refund period in certain of our jurisdictions. As a result, our effective income tax rate decreased to 18.8% for the nine months ended June 30, 2021. Our effective income tax rate in the prior year period was 19.2%, which reflected the income tax benefit recognized upon enactment of the new Kansas legislation. Currently, the regulatory excess net deferred tax liability is being returned over various periods. Of this amount, $243.0 million, is being returned to customers over 35 - 60 months. An additional $430.1 million is being returned to customers on a provisional basis over 15 - 69 years until our regulators establish the final refund periods. We will work with the Kansas Corporation Commission during our next rate proceeding to determine the refund period for the remaining $12.1 million.

Segment Information

Segment Information	9 Months Ended
	Jun. 30, 2021
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, 2020. Income statements and capital expenditures for the three and nine months ended June 30, 2021 and 2020 by segment are presented in the following tables: Three Months Ended June 30, 2021 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 557,931 $ 47,622 $ — $ 605,553 Intersegment revenues 819 115,365 (116,184) — Total operating revenues 558,750 162,987 (116,184) 605,553 Purchased gas cost 202,050 691 (115,871) 86,870 Operation and maintenance expense 130,454 54,329 (313) 184,470 Depreciation and amortization expense 86,099 33,249 — 119,348 Taxes, other than income 72,024 9,451 — 81,475 Operating income 68,123 65,267 — 133,390 Other non-operating income 1,060 4,827 — 5,887 Interest charges 8,540 12,422 — 20,962 Income before income taxes 60,643 57,672 — 118,315 Income tax expense 7,354 8,550 — 15,904 Net income $ 53,289 $ 49,122 $ — $ 102,411 Capital expenditures $ 398,416 $ 113,816 $ — $ 512,232 Three Months Ended June 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 434,650 $ 58,345 $ — $ 492,995 Intersegment revenues 658 99,663 (100,321) — Total operating revenues 435,308 158,008 (100,321) 492,995 Purchased gas cost 126,093 (11) (100,010) 26,072 Operation and maintenance expense 107,537 42,234 (311) 149,460 Depreciation and amortization expense 77,187 29,917 — 107,104 Taxes, other than income 61,980 9,344 — 71,324 Operating income 62,511 76,524 — 139,035 Other non-operating income 5,167 2,068 — 7,235 Interest charges 7,969 11,611 — 19,580 Income before income taxes 59,709 66,981 — 126,690 Income tax expense 810 8,089 — 8,899 Net income $ 58,899 $ 58,892 $ — $ 117,791 Capital expenditures $ 342,385 $ 68,551 $ — $ 410,936 Nine Months Ended June 30, 2021 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,715,644 $ 123,462 $ — $ 2,839,106 Intersegment revenues 2,430 353,406 (355,836) — Total operating revenues 2,718,074 476,868 (355,836) 2,839,106 Purchased gas cost 1,304,269 (440) (354,890) 948,939 Operation and maintenance expense 363,246 117,188 (946) 479,488 Depreciation and amortization expense 254,636 98,633 — 353,269 Taxes, other than income 214,991 28,385 — 243,376 Operating income 580,932 233,102 — 814,034 Other non-operating income 1,135 13,658 — 14,793 Interest charges 33,269 35,799 — 69,068 Income before income taxes 548,798 210,961 — 759,759 Income tax expense 109,481 33,435 — 142,916 Net income $ 439,317 $ 177,526 $ — $ 616,843 Capital expenditures $ 1,000,616 $ 357,344 $ — $ 1,357,960 Nine Months Ended June 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,194,786 $ 151,437 $ — $ 2,346,223 Intersegment revenues 2,031 300,984 (303,015) — Total operating revenues 2,196,817 452,421 (303,015) 2,346,223 Purchased gas cost 942,586 290 (302,053) 640,823 Operation and maintenance expense 337,740 112,751 (962) 449,529 Depreciation and amortization expense 229,526 88,556 — 318,082 Taxes, other than income 190,636 23,899 — 214,535 Operating income 496,329 226,925 — 723,254 Other non-operating income 1,930 7,203 — 9,133 Interest charges 35,128 33,852 — 68,980 Income before income taxes 463,131 200,276 — 663,407 Income tax expense 87,411 39,886 — 127,297 Net income $ 375,720 $ 160,390 $ — $ 536,110 Capital expenditures $ 1,119,945 $ 285,728 $ — $ 1,405,673 Balance sheet information at June 30, 2021 and September 30, 2020 by segment is presented in the following tables: June 30, 2021 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 10,802,062 $ 3,675,687 $ — $ 14,477,749 Total assets $ 18,563,345 $ 3,906,816 $ (3,154,726) $ 19,315,435 September 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 9,944,978 $ 3,410,369 $ — $ 13,355,347 Total assets $ 14,578,176 $ 3,647,907 $ (2,867,051) $ 15,359,032

Earnings Per Share

Earnings Per Share	9 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per ShareWe use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock. 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 nine months ended June 30, 2021 and 2020 are calculated as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 102,411 $ 117,791 $ 616,843 $ 536,110 Less: Income allocated to participating securities 70 88 440 408 Income available to common shareholders $ 102,341 $ 117,703 $ 616,403 $ 535,702 Basic weighted average shares outstanding 131,358 123,026 129,185 122,352 Net income per share — Basic $ 0.78 $ 0.96 $ 4.77 $ 4.38 Diluted Earnings Per Share Income available to common shareholders $ 102,341 $ 117,703 $ 616,403 $ 535,702 Effect of dilutive shares — — — — Income available to common shareholders $ 102,341 $ 117,703 $ 616,403 $ 535,702 Basic weighted average shares outstanding 131,358 123,026 129,185 122,352 Dilutive shares 128 6 44 111 Diluted weighted average shares outstanding 131,486 123,032 129,229 122,463 Net income per share - Diluted $ 0.78 $ 0.96 $ 4.77 $ 4.37

Revenue and Accounts Receivable

Revenue and Accounts Receivable	9 Months Ended
	Jun. 30, 2021
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, 2020. The following tables disaggregate our revenue from contracts with customers by customer type and segment and provide a reconciliation to total operating revenues, including intersegment revenues, for the three and nine months ended June 30, 2021 and 2020. Three Months Ended June 30, 2021 Three Months Ended June 30, 2020 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 336,016 $ — $ 286,937 $ — Commercial 157,314 — 101,055 — Industrial 25,348 — 17,019 — Public authority and other 8,870 — 7,063 — Total gas sales revenues 527,548 — 412,074 — Transportation revenues 25,903 164,619 22,532 164,675 Miscellaneous revenues 2,615 3,895 2,793 2,277 Revenues from contracts with customers 556,066 168,514 437,399 166,952 Alternative revenue program revenues (1) 2,206 (5,527) (2,567) (8,944) Other revenues 478 — 476 — Total operating revenues $ 558,750 $ 162,987 $ 435,308 $ 158,008 Nine Months Ended June 30, 2021 Nine Months Ended June 30, 2020 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 1,821,570 $ — $ 1,435,328 $ — Commercial 692,443 — 543,148 — Industrial 81,122 — 67,572 — Public authority and other 42,159 — 34,747 — Total gas sales revenues 2,637,294 — 2,080,795 — Transportation revenues 84,643 480,945 77,676 471,433 Miscellaneous revenues 8,336 12,921 16,565 8,767 Revenues from contracts with customers 2,730,273 493,866 2,175,036 480,200 Alternative revenue program revenues (1) (13,666) (16,998) 20,320 (27,779) Other revenues 1,467 — 1,461 — Total operating revenues $ 2,718,074 $ 476,868 $ 2,196,817 $ 452,421 (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 we share with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a regulatorily determined 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. The receivable balances are short term and generally do not extend beyond one month. To minimize credit risk, we assess the credit worthiness of new customers, require deposits where necessary, assess late fees, pursue collection activities and disconnect service for nonpayment. After disconnection, accounts are written off when deemed uncollectible. As described in Note 2 to the unaudited condensed consolidated financial statements, on October 1, 2020, we adopted new accounting guidance which requires credit losses on our accounts receivable to be measured using an expected credit loss model over the entire contractual term from the date of initial recognition. At each reporting period, we assess the allowance for uncollectible accounts based on historical experience, current conditions and consideration of expected future conditions. Circumstances which could affect our estimates include, but are not limited to, customer credit issues, the level of natural gas prices, customer deposits and general economic conditions. Due to the COVID-19 pandemic, in March 2020 we temporarily suspended disconnecting customers for nonpayment and stopped charging late fees. We resumed disconnection activity during the third quarter of fiscal 2021. We are actively working with our customers experiencing financial hardship to offer flexible payment options and directing them to aid agencies for financial assistance. Our allowance for uncollectible accounts reflects the expected impact on our customers’ ability to pay. Rollforwards of our allowance for uncollectible accounts for the three and nine months ended June 30, 2021 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 78 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 June 30, 2021 (In thousands) Beginning balance, March 31, 2021 $ 44,680 Current period provisions 14,403 Write-offs charged against allowance (2,875) Recoveries of amounts previously written off 437 Ending balance, June 30, 2021 $ 56,645 Nine Months Ended June 30, 2021 (In thousands) Beginning balance, September 30, 2020 $ 29,949 Current period provisions 32,872 Write-offs charged against allowance (7,544) Recoveries of amounts previously written off 1,368 Ending balance, June 30, 2021 $ 56,645

Debt

Debt	9 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	Debt The 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, 2020. Other than as described below, there were no material changes in the terms of our debt instruments during the nine months ended June 30, 2021. Long-term debt at June 30, 2021 and September 30, 2020 consisted of the following: June 30, 2021 September 30, 2020 (In thousands) Unsecured 0.625% Senior Notes, due 2023 $ 1,100,000 $ — Unsecured 3.00% Senior Notes, due 2027 500,000 500,000 Unsecured 2.625% Senior Notes, due 2029 300,000 300,000 Unsecured 1.50% Senior Notes, due 2031 600,000 — Unsecured 5.95% Senior Notes, due 2034 200,000 200,000 Unsecured 5.50% Senior Notes, due 2041 400,000 400,000 Unsecured 4.15% Senior Notes, due 2043 500,000 500,000 Unsecured 4.125% Senior Notes, due 2044 750,000 750,000 Unsecured 4.30% Senior Notes, due 2048 600,000 600,000 Unsecured 4.125% Senior Notes, due 2049 450,000 450,000 Unsecured 3.375% Senior Notes, due 2049 500,000 500,000 Floating-rate term loan, due April 2022 200,000 200,000 Floating-rate Senior Notes, due 2023 1,100,000 — Medium-term note Series A, 1995-1, 6.67%, due 2025 10,000 10,000 Unsecured 6.75% Debentures, due 2028 150,000 150,000 Finance lease obligations 18,844 8,631 Total long-term debt 7,378,844 4,568,631 Less: Original issue discount on unsecured senior notes and debentures 2,920 583 Debt issuance cost 46,977 36,104 Current maturities 200,442 165 $ 7,128,505 $ 4,531,779 On March 9, 2021, we completed a public offering of $1.1 billion of 0.625% senior notes due 2023, with an effective interest rate of 0.834%, after giving effect to the offering costs, and $1.1 billion floating rate senior notes due 2023 that bear interest at a rate equal to the Three-Month LIBOR rate plus 0.38%. The net proceeds from the offering, after the underwriting discount and offering expenses, of $2.2 billion were used for the payment of unplanned natural gas costs incurred during Winter Storm Uri. See Note 8 to the unaudited condensed consolidated financial statements for further information. The notes are subject to optional redemption at any time on or after September 9, 2021 at a price equal to 100 percent of the principal amount of the notes being redeemed, plus any accrued and unpaid interest thereon, if any, to, but excluding, the redemption date. On October 1, 2020, we completed a public offering of $600 million of 1.50% senior notes due 2031, with an effective interest rate of 1.71%, after giving effect to the offering costs and settlement of our interest rate swaps. The net proceeds from the offering, after the underwriting discount and offering expenses, of $592.3 million, were used for general corporate purposes, including the repayment of working capital borrowings pursuant to our commercial paper program and the related settlement of our interest rate swaps. 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 with an equity-to-total-capitalization ratio between 50% and 60%, inclusive of long-term and short-term debt. 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 was replaced on March 31, 2021, with a new five-year unsecured $1.5 billion credit facility that expires on March 31, 2026. The new facility bears interest at a base rate or at a LIBOR-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 LIBOR-based advances, based on the Company’s credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the total committed loan to $1.75 billion. At June 30, 2021 and September 30, 2020, there were no amounts outstanding under our commercial paper program. We had a $600 million 364-day unsecured revolving credit facility, which was replaced on March 31, 2021, with a new $900 million three-year unsecured revolving credit facility. This new facility will be used primarily to provide additional working capital funding. The new facility bears interest at a base rate or at a LIBOR-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 LIBOR-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 June 30, 2021, there were no borrowings outstanding under this facility. Additionally, we have a $50 million 364-day unsecured facility, which was renewed April 1, 2021 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of June 30, 2021. Finally, we have a $50 million 364-day unsecured revolving credit facility, which was renewed April 29, 2021 and is used to issue letters of credit and to provide working capital funding. At June 30, 2021, there were no borrowings outstanding under this facility; however, outstanding letters of credit reduced the total amount available to us to $44.4 million. Debt covenants The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total-debt-to-total-capitalization of no greater than 70 percent. At June 30, 2021, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 50 percent. In addition, both the interest margin and the fee that we pay on unused amounts under certain of these facilities are subject to adjustment depending upon our credit ratings. These credit facilities and our public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as certain of our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or if not paid at maturity. We were in compliance with all of our debt covenants as of June 30, 2021. If we were unable to comply with our debt covenants, we would likely be required to repay our outstanding balances on demand, provide additional collateral or take other corrective actions.

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Shareholders' Equity	Shareholders' EquityThe following tables present a reconciliation of changes in stockholders' equity for the three and nine months ended June 30, 2021 and 2020. Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2020 125,882,477 $ 629 $ 4,377,149 $ (57,589) $ 2,471,014 $ 6,791,203 Net income — — — — 217,678 217,678 Other comprehensive income — — — 60,121 — 60,121 Cash dividends ($0.625 per share) — — — — (79,023) (79,023) Common stock issued: Public and other stock offerings 2,126,118 11 219,998 — — 220,009 Stock-based compensation plans 144,366 1 3,167 — — 3,168 Balance, December 31, 2020 128,152,961 641 4,600,314 2,532 2,609,669 7,213,156 Net income — — — — 296,754 296,754 Other comprehensive income — — — 137,939 — 137,939 Cash dividends ($0.625 per share) — — — — (80,325) (80,325) Common stock issued: Public and other stock offerings 2,498,026 12 248,948 — — 248,960 Stock-based compensation plans 16,122 — 4,441 — — 4,441 Balance, March 31, 2021 130,667,109 653 4,853,703 140,471 2,826,098 7,820,925 Net income — — — — 102,411 102,411 Other comprehensive loss — — — (79,232) — (79,232) Cash dividends ($0.625 per share) — — — — (81,912) (81,912) Common stock issued: Public and other stock offerings 39,078 1 3,829 — — 3,830 Stock-based compensation plans 80,852 — 7,736 — — 7,736 Balance, June 30, 2021 130,787,039 $ 654 $ 4,865,268 $ 61,239 $ 2,846,597 $ 7,773,758 Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2019 119,338,925 $ 597 $ 3,712,194 $ (114,583) $ 2,152,015 $ 5,750,223 Net income — — — — 178,673 178,673 Other comprehensive income — — — 1,052 — 1,052 Cash dividends ($0.575 per share) — — — — (69,557) (69,557) Common stock issued: Public and other stock offerings 2,758,929 13 263,259 — — 263,272 Stock-based compensation plans 164,549 1 4,111 — — 4,112 Balance, December 31, 2019 122,262,403 611 3,979,564 (113,531) 2,261,131 6,127,775 Net income — — — — 239,646 239,646 Other comprehensive income — — — 890 — 890 Cash dividends ($0.575 per share) — — — — (70,520) (70,520) Common stock issued: Public and other stock offerings 38,662 1 3,095 — — 3,096 Stock-based compensation plans 7,660 — 3,528 — — 3,528 Balance, March 31, 2020 122,308,725 612 3,986,187 (112,641) 2,430,257 6,304,415 Net income — — — — 117,791 117,791 Other comprehensive loss — — — (4,086) — (4,086) Cash dividends ($0.575 per share) — — — — (70,597) (70,597) Common stock issued: Public and other stock offerings 965,576 5 105,799 — — 105,804 Stock-based compensation plans 76,966 — 8,144 — — 8,144 Balance, June 30, 2020 123,351,267 $ 617 $ 4,100,130 $ (116,727) $ 2,477,451 $ 6,461,471 Shelf Registration, At-the-Market Equity Sales Program and Equity Issuances On June 29, 2021, 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 June 29, 2024. This shelf registration statement replaced our previous shelf registration statement which was filed on February 11, 2020. At June 30, 2021, $4.0 billion of securities were available for issuance under the shelf registration statement. On June 29, 2021, we filed a prospectus supplement under the shelf registration statement relating to an at-the-market (ATM) equity sales program (June 2021 ATM) under which we may issue and sell shares of our common stock up to an aggregate offering price of $1.0 billion (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 February 12, 2020 (February 2020 ATM). During the nine months ended June 30, 2021, we executed forward sales under our February 2020 ATM equity sales program with various forward sellers who borrowed and sold 3,451,356 shares of our common stock at an aggregate price of $338.3 million. During the nine months ended June 30, 2021, we also settled forward sale agreements with respect to 4,537,669 shares that had been borrowed and sold by various forward sellers under the February 2020 ATM program for net proceeds of $460.7 million. As of June 30, 2021, $1.0 billion of equity was available for issuance under the June 2021 ATM program. Additionally, we had $213.1 million in available proceeds, based on a net price of $94.71 per share, from outstanding forward sale agreements, available through June 30, 2022. 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 as they are amortized. 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, 2020 $ 238 $ (57,827) $ (57,589) Other comprehensive income (loss) before reclassifications (165) 115,568 115,403 Amounts reclassified from accumulated other comprehensive income — 3,425 3,425 Net current-period other comprehensive income (loss) (165) 118,993 118,828 June 30, 2021 $ 73 $ 61,166 $ 61,239 Available- Interest Rate Total (In thousands) September 30, 2019 $ 132 $ (114,715) $ (114,583) Other comprehensive income (loss) before reclassifications 202 (4,932) (4,730) Amounts reclassified from accumulated other comprehensive income (2) 2,588 2,586 Net current-period other comprehensive income (loss) 200 (2,344) (2,144) June 30, 2020 $ 332 $ (117,059) $ (116,727)

Interim Pension and Other Postr

Interim Pension and Other Postretirement Benefit Plan Information	9 Months Ended
	Jun. 30, 2021
Retirement Benefits, Description [Abstract]
Interim Pension and Other Postretirement Benefit Plan Information	Interim Pension and Other Postretirement Benefit Plan Information The components of our net periodic pension cost for our pension and other postretirement benefit plans for the three and nine months ended June 30, 2021 and 2020 are presented in the following tables. Most of these costs are recoverable through our tariff rates. A portion of these costs is capitalized into our rate base or deferred as a regulatory asset or liability. The remaining costs are recorded as a component of operation and maintenance expense or other non-operating expense. In the third quarter of fiscal 2021, due to the retirement of certain executives, we recognized a settlement charge of $9.0 million associated with our Supplemental Executive Retirement Plan and revalued the net periodic pension cost for the remainder of fiscal 2021. The revaluation of the net periodic pension cost for our Supplemental Executive Retirement Plan resulted in an increase in the discount rate, effective May 31, 2021, to 3.11% from 2.80%, which will decrease our net periodic pension cost by approximately $0.5 million for the remainder of the fiscal year. Three Months Ended June 30 Pension Benefits Other Benefits 2021 2020 2021 2020 (In thousands) Components of net periodic pension cost: Service cost $ 4,609 $ 4,652 $ 4,305 $ 3,366 Interest cost (1) 5,016 5,843 2,661 2,653 Expected return on assets (1) (6,978) (7,079) (2,613) (2,625) Amortization of prior service cost (credit) (1) (58) (58) 44 43 Amortization of actuarial (gain) loss (1) 3,062 3,242 — (334) Settlements (1) 8,999 — — — Net periodic pension cost $ 14,650 $ 6,600 $ 4,397 $ 3,103 Nine Months Ended June 30 Pension Benefits Other Benefits 2021 2020 2021 2020 (In thousands) Components of net periodic pension cost: Service cost $ 13,834 $ 13,957 $ 12,917 $ 10,099 Interest cost (1) 15,072 17,529 7,981 7,959 Expected return on assets (1) (20,934) (21,237) (7,841) (7,874) Amortization of prior service cost (credit) (1) (174) (174) 130 130 Amortization of actuarial (gain) loss (1) 9,405 9,725 — (1,003) Settlements (1) 8,999 — — — Net periodic pension cost $ 26,202 $ 19,800 $ 13,187 $ 9,311 (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, 2020. For the nine months ended June 30, 2021 we contributed $16.8 million to our postretirement medical plans. We anticipate contributing a total of between $15 million and $25 million to our postretirement plans during fiscal 2021.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Jun. 30, 2021
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 maintain liability insurance for various risks associated with the operation of our natural gas pipelines and facilities, including for property damage and bodily injury. These liability insurance policies generally require us to be responsible for the first $1.0 million (self-insured retention) of each incident. The National Transportation Safety Board (NTSB) held a public meeting on January 12, 2021 to determine the probable cause of the incident that occurred at a Dallas, Texas residence on February 23, 2018 that resulted in one fatality and injuries to four other residents. At the meeting, the Board deliberated and voted on proposed findings of fact, a probable cause statement, and safety recommendations. On February 8, 2021, the NTSB issued its final report that included an Executive Summary, Findings, Probable Cause, and Recommendations. Also on February 8, 2021, safety recommendations letters were distributed to recommendation recipients, including Atmos Energy. Atmos Energy timely provided a written response on May 7, 2021. Following the release of the NTSB’s final report, the Railroad Commission of Texas (RRC) completed its safety evaluation related to the same incident finding four alleged violations and initiated an enforcement proceeding to pursue administrative penalties totaling $1.6 million. Atmos Energy is working with the RRC to resolve the alleged violations and satisfy the administrative penalties. The NTSB is investigating a worksite accident that occurred in Farmersville, Texas on June 28, 2021 that resulted in two fatalities and injuries to two others. Together with the Railroad Commission of Texas and the Pipeline and Hazardous Materials Safety Administration, Atmos Energy is a party to the investigation and in that capacity is working closely with all parties to help determine the cause of this incident. On July 16, 2021, a civil action was filed in Dallas, Texas against Atmos Energy and one of its contractors in response to the June 28, 2021 incident. 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 indexed to natural gas hubs. These purchase commitment contracts are detailed in our Annual Report on Form 10-K for the fiscal year ended September 30, 2020. At June 30, 2021, we were committed to purchase 54.3 Bcf within one year and 17.6 Bcf within two Rate Regulatory Proceedings As of June 30, 2021, routine rate regulatory proceedings were in progress in several of our service areas, which are discussed in further detail below in Management’s Discussion and Analysis — Recent Ratemaking Developments . Except for these proceedings, there were no material changes to rate regulatory proceedings for the nine months ended June 30, 2021.

Financial Instruments

Financial Instruments	9 Months Ended
	Jun. 30, 2021
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 14 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2020. During the nine months ended June 30, 2021, 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 2020-2021 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 39 percent, or 15.8 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 June 2021, we entered into forward starting interest rate swaps to effectively fix the Treasury yield component associated with $525 million of planned issuances of unsecured senior notes. 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 June 30, 2021: Planned Debt Issuance Date Amount Hedged Effective Interest Rate (In thousands) Fiscal 2022 $ 600,000 1.53 % Fiscal 2023 400,000 1.56 % Fiscal 2024 75,000 2.19 % Fiscal 2025 400,000 1.56 % Fiscal 2026 100,000 2.21 % $ 1,575,000 Additionally, in July 2021, we entered into forward starting interest rate swaps to effectively fix the Treasury yield component associated with $875 million of planned issuances of unsecured senior notes, which we designated as cash flow hedges at the time the agreements were 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 June 30, 2021, our financial instruments were comprised of both long and short commodity positions. A long position is a contract to purchase the commodity, while a short position is a contract to sell the commodity. As of June 30, 2021, we had 16,797 MMcf of net long commodity contracts outstanding. These contracts have not been designated as hedges. Financial Instruments on the Balance Sheet The following tables present the fair value and balance sheet classification of our financial instruments as of June 30, 2021 and September 30, 2020. 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, for June 30, 2021 and September 30, 2020, no gross amounts and no cash collateral were netted within our consolidated balance sheet. Balance Sheet Location Assets Liabilities (In thousands) June 30, 2021 Designated As Hedges: Interest rate contracts Other current assets / $ 89,260 $ (2,902) Interest rate contracts Deferred charges and other assets / 136,242 (574) Total 225,502 (3,476) Not Designated As Hedges: Commodity contracts Other current assets / 12,024 (1,926) Commodity contracts Deferred charges and other assets / 1,393 — Total 13,417 (1,926) Gross / Net Financial Instruments $ 238,919 $ (5,402) Balance Sheet Location Assets Liabilities (In thousands) September 30, 2020 Designated As Hedges: Interest rate contracts Deferred charges and other assets / $ 73,055 $ — Total 73,055 — Not Designated As Hedges: Commodity contracts Other current assets / 5,687 (2,015) Commodity contracts Deferred charges and other assets / 1,936 — Total 7,623 (2,015) Gross / Net Financial Instruments $ 80,678 $ (2,015) 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 loss on settled interest rate agreements reclassified from AOCI into interest charges on our condensed consolidated statements of comprehensive income for the three months ended June 30, 2021 and 2020 was $1.5 million and $1.4 million and for the nine months ended June 30, 2021 and 2020 was $4.4 million and $4.1 million. The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and nine months ended June 30, 2021 and 2020. The amounts included in the table below exclude gains and losses arising from ineffectiveness because those amounts are immediately recognized in the statement of comprehensive income as incurred. Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (80,338) $ (4,932) $ 115,568 $ (4,932) Recognition of losses in earnings due to settlements: Interest rate agreements 1,142 482 3,425 2,588 Total other comprehensive income (loss) from hedging, net of tax $ (79,196) $ (4,450) $ 118,993 $ (2,344) Deferred gains (losses) recorded in AOCI associated with our interest rate agreements are recognized in earnings as they are amortized over the terms of the underlying debt instruments. As of June 30, 2021, we had $111.1 million of net realized losses 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 losses 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 2049. 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 $ (4,566) Thereafter (106,511) Total $ (111,077) Financial Instruments Not Designated as Hedges As discussed above, commodity contracts which are used in our distribution segment are not designated as hedges. However, there is no earnings impact on our distribution segment as a result of the use of these financial instruments because the gains and losses arising from the use of these financial instruments are recognized in the consolidated statement of comprehensive income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue. Accordingly, the impact of these financial instruments is excluded from this presentation.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Jun. 30, 2021
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, 2020. During the nine months ended June 30, 2021, 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 9 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2020. Quantitative Disclosures Financial Instruments The classification of our fair value measurements requires judgment regarding the degree to which market data is observable or corroborated by observable market data. Authoritative accounting literature establishes a fair value hierarchy that prioritizes the inputs used to measure fair value based on observable and unobservable data. The hierarchy categorizes the inputs into three levels, with the highest priority given to unadjusted quoted prices in active markets for identical assets and liabilities (Level 1), with the lowest priority given to unobservable inputs (Level 3). The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of June 30, 2021 and September 30, 2020. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and June 30, 2021 (In thousands) Assets: Financial instruments $ — $ 238,919 $ — $ — $ 238,919 Debt and equity securities Registered investment companies 35,166 — — — 35,166 Bond mutual funds 34,270 — — — 34,270 Bonds (2) — 32,264 — — 32,264 Money market funds — 4,017 — — 4,017 Total debt and equity securities 69,436 36,281 — — 105,717 Total assets $ 69,436 $ 275,200 $ — $ — $ 344,636 Liabilities: Financial instruments $ — $ 5,402 $ — $ — $ 5,402 Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and September 30, 2020 (In thousands) Assets: Financial instruments $ — $ 80,678 $ — $ — $ 80,678 Debt and equity securities Registered investment companies 37,831 — — — 37,831 Bond mutual funds 29,166 — — — 29,166 Bonds (2) — 32,900 — — 32,900 Money market funds — 4,055 — — 4,055 Total debt and equity securities 66,997 36,955 — — 103,952 Total assets $ 66,997 $ 117,633 $ — $ — $ 184,630 Liabilities: Financial instruments $ — $ 2,015 $ — $ — $ 2,015 (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 further in Note 2 to the unaudited condensed consolidated financial statements, we adopted ASC 326 effective October 1, 2020. In accordance with the new guidance, we evaluate the performance of our available-for-sale debt securities on an investment by investment basis for impairment, taking into consideration the investment’s purpose, volatility, current returns and any intent to sell the security. As of June 30, 2021, no allowance for credit losses was recorded for our available-for-sale debt securities. At June 30, 2021 and September 30, 2020, the amortized cost of our available-for-sale debt securities was $32.2 million and $32.6 million. At June 30, 2021, we maintained investments in bonds that have contractual maturity dates ranging from July 2021 through April 2024. Other Fair Value Measures Our long-term debt is recorded at carrying value. The fair value of our long-term debt, excluding finance leases, is determined using third party market value quotations, which are considered Level 1 fair value measurements for debt instruments with a recent, observable trade or Level 2 fair value measurements for debt instruments where fair value is determined using the most recent available quoted market price. The carrying value of our finance leases materially approximates fair value. The following table presents the carrying value and fair value of our long-term debt, excluding finance leases, debt issuance costs and original issue premium or discount, as of June 30, 2021 and September 30, 2020: June 30, 2021 September 30, 2020 (In thousands) Carrying Amount $ 7,360,000 $ 4,560,000 Fair Value $ 8,101,744 $ 5,597,183

Concentration of Credit Risk

Concentration of Credit Risk	9 Months Ended
	Jun. 30, 2021
Risks and Uncertainties [Abstract]
Concentration of Credit Risk	Concentration of Credit RiskInformation regarding our concentration of credit risk is disclosed in Note 16 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2020. During the nine months ended June 30, 2021, there were no material changes in our concentration of credit risk.

Winter Storm Uri

Winter Storm Uri	9 Months Ended
	Jun. 30, 2021
Unusual or Infrequent Items, or Both [Abstract]
Winter Storm Uri	Winter Storm Uri Overview A historic winter storm impacted supply, market pricing and demand for natural gas in our service territories in mid-February. 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 by the end of March 2021. Incremental Financing As discussed in Note 6 to the unaudited condensed consolidated financial statements, on March 9, 2021, we completed a public offering of $2.2 billion in debt securities and the net proceeds from the offering, after the underwriting discount and offering expenses, were used to substantially fund these purchased gas costs. As a result of this unplanned debt issuance, S&P lowered its long-term/short-term credit ratings from A/A-1 to A-/A-2 and placed our ratings under negative outlook. Moody’s reaffirmed its long-term and short-term credit ratings and placed our ratings under negative outlook. These credit rating adjustments and the issuance of unplanned debt did not impact our ability to satisfy our debt covenants. 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, as of June 30, 2021, we have recorded a $2.1 billion regulatory asset for incremental costs, including carrying costs, incurred in Kansas ($77.1 million) and Texas ($2,016.7 million) within deferred charges and other assets on our condensed consolidated balance sheet. These costs are subject to review for prudency by each commission and may be adjusted. Income Taxes We deduct our purchased gas costs for federal income tax purposes in the period they are paid. Based on our current projection of taxable income for fiscal 2021 and the expected magnitude of the purchased gas cost deduction, we recorded a $469.4 million (tax effected) increase in our net operating loss carryforwards and a corresponding increase to our deferred tax liability as of June 30, 2021. At June 30, 2021, we had $804.7 million (tax effected) of federal net operating loss carryforwards. The federal net operating loss carryforwards are available to offset future taxable income. Net operating loss carryforwards incurred prior to December 22, 2017 begin to expire in 2029. The Company also has $57.0 million (tax effected) of state net operating loss carryforwards (net of $15.2 million of federal effects) and $1.8 million of state tax credits carryforwards (net of $0.5 million of federal effects). Depending on the jurisdiction in which the state net operating loss was generated, the carryforwards are subject to expiration through the remainder of fiscal 2021. Securitization Legislation 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 introduced securitization legislation. The following summarizes the status of the legislation as of the date of this filing. Kansas The Kansas securitization legislation, which became effective April 9, 2021, permits a natural gas public utility, in its sole discretion, to apply to the KCC for a financing order for the recovery of qualified extraordinary costs through the issuance of bonds. Within 25 days after a complete application is filed, the KCC shall establish a procedural schedule that requires it to issue a decision on the application within 180 days from the date a complete application was filed. Utilities may apply for a recovery period of up to 32 years. We plan to file with the KCC an application to securitize the extraordinary gas costs incurred during Winter Storm Uri. Texas On June 16, 2021, House Bill 1520, relating to certain extraordinary costs incurred by certain gas utilities relating to Winter Storm Uri and a study of measures to mitigate similar future costs; providing authority to issue bonds and impose fees and assessments, became effective. House Bill 1520 authorizes the RRC to issue a statewide securitization financing order directing the Texas Public Finance authority to issue bonds (customer rate relief bonds) for gas utilities that choose to participate to recover extraordinary costs incurred to secure gas supply and to provide service during Winter Storm Uri, and to restore gas utility systems after that event, thereby providing rate relief to customers by extending the period during which these extraordinary costs would otherwise be recovered and supporting the financial strength and stability of gas utility companies. The legislation provides that natural gas utilities file an application with the RRC and submit extraordinary gas costs incurred during Winter Storm Uri for a prudency review by July 30, 2021. The RRC has 150 days to approve each application. Following the approval of all applications, the RRC will issue a financing order to the Texas Public Financing Authority authorizing the issuance of customer rate relief bonds to securitize the aggregated extraordinary costs for all participating utilities within 180 days. The participating utilities, as servicers acting on behalf of the state of the securitization financing, will bill and collect customer rate relief charges from their current and future customers and remit the collections to the state issuer of the securitization financing. On July 30, 2021, we filed with the RRC an application to securitize $2.0 billion of extraordinary gas costs incurred during Winter Storm Uri. This amount also includes an estimate of carrying costs and administrative costs that we expect to incur in connection with the resolution of this filing.

Unaudited Financial Informati_2

Unaudited Financial Information (Policies)	9 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Accounting pronouncements adopted and not yet adopted	Accounting pronouncements adopted in fiscal 2021 Effective October 1, 2020, we adopted new accounting guidance that requires credit losses on most financial assets measured at amortized cost and certain other instruments to be measured using an expected credit loss model. Under this model, we estimate credit losses over the entire contractual term of the instrument from the date of initial recognition of that instrument. The new guidance also introduces a new impairment recognition model for available-for-sale debt securities that will require credit losses to be recorded through an allowance account. We adopted the new guidance using a modified retrospective method. The adoption of this standard did not have a material impact on our financial position, results of operations and cash flows and no adjustments were made to October 1, 2020 opening balances as a result of this adoption. As required under the modified retrospective method of adoption, results for the reporting period beginning after October 1, 2020 are presented under Accounting Standards Codification (ASC) 326, while prior period amounts are not adjusted. See Notes 5 and 12 to the unaudited condensed consolidated financial statements for further discussion of implementation of the standard. Accounting pronouncements that will be effective after fiscal 2021 In March 2020, the Financial Accounting Standards Board (FASB) issued optional guidance which will ease the potential burden in accounting for or recognizing the effects of reference rate reform on financial reporting. The amendments provide optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions affected by the cessation of the London Interbank Offered Rate (LIBOR). The amendments can be elected immediately, as of March 12, 2020, through December 31, 2022. We are currently evaluating if we will apply the optional guidance as we assess the impact
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 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, 2020. During the nine months ended June 30, 2021, there were no changes in these methods.

Unaudited Financial Informati_3

Unaudited Financial Information (Table)	9 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Schedule of Regulatory Assets	Significant regulatory assets and liabilities as of June 30, 2021 and September 30, 2020 included the following: June 30, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 135,411 $ 149,089 Infrastructure mechanisms (1) 222,263 183,943 Winter Storm Uri incremental costs (2) 2,093,779 — Deferred gas costs 27,593 40,593 Regulatory excess deferred taxes 8,838 — Recoverable loss on reacquired debt 3,893 4,894 Deferred pipeline record collection costs 31,283 29,839 Other 3,952 6,283 $ 2,527,012 $ 414,641 Regulatory liabilities: Regulatory excess deferred taxes $ 694,018 $ 718,651 Regulatory cost of removal obligation 536,317 531,096 Deferred gas costs 55,572 19,985 Asset retirement obligation 20,348 20,348 APT annual adjustment mechanism 37,358 57,379 Other 19,371 19,554 $ 1,362,984 $ 1,367,013 (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 related carrying costs. See Note 8 to the unaudited condensed consolidated financial statements for further information. This amount is recorded within deferred charges and other assets on the condensed consolidated balance sheet as of June 30, 2021.
Schedule of Regulatory Liabilities	Significant regulatory assets and liabilities as of June 30, 2021 and September 30, 2020 included the following: June 30, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 135,411 $ 149,089 Infrastructure mechanisms (1) 222,263 183,943 Winter Storm Uri incremental costs (2) 2,093,779 — Deferred gas costs 27,593 40,593 Regulatory excess deferred taxes 8,838 — Recoverable loss on reacquired debt 3,893 4,894 Deferred pipeline record collection costs 31,283 29,839 Other 3,952 6,283 $ 2,527,012 $ 414,641 Regulatory liabilities: Regulatory excess deferred taxes $ 694,018 $ 718,651 Regulatory cost of removal obligation 536,317 531,096 Deferred gas costs 55,572 19,985 Asset retirement obligation 20,348 20,348 APT annual adjustment mechanism 37,358 57,379 Other 19,371 19,554 $ 1,362,984 $ 1,367,013 (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 related carrying costs. See Note 8 to the unaudited condensed consolidated financial statements for further information. This amount is recorded within deferred charges and other assets on the condensed consolidated balance sheet as of June 30, 2021.

Segment Information (Table)

Segment Information (Table)	9 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Income statements and capital expenditures for the three and nine months ended June 30, 2021 and 2020 by segment are presented in the following tables: Three Months Ended June 30, 2021 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 557,931 $ 47,622 $ — $ 605,553 Intersegment revenues 819 115,365 (116,184) — Total operating revenues 558,750 162,987 (116,184) 605,553 Purchased gas cost 202,050 691 (115,871) 86,870 Operation and maintenance expense 130,454 54,329 (313) 184,470 Depreciation and amortization expense 86,099 33,249 — 119,348 Taxes, other than income 72,024 9,451 — 81,475 Operating income 68,123 65,267 — 133,390 Other non-operating income 1,060 4,827 — 5,887 Interest charges 8,540 12,422 — 20,962 Income before income taxes 60,643 57,672 — 118,315 Income tax expense 7,354 8,550 — 15,904 Net income $ 53,289 $ 49,122 $ — $ 102,411 Capital expenditures $ 398,416 $ 113,816 $ — $ 512,232 Three Months Ended June 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 434,650 $ 58,345 $ — $ 492,995 Intersegment revenues 658 99,663 (100,321) — Total operating revenues 435,308 158,008 (100,321) 492,995 Purchased gas cost 126,093 (11) (100,010) 26,072 Operation and maintenance expense 107,537 42,234 (311) 149,460 Depreciation and amortization expense 77,187 29,917 — 107,104 Taxes, other than income 61,980 9,344 — 71,324 Operating income 62,511 76,524 — 139,035 Other non-operating income 5,167 2,068 — 7,235 Interest charges 7,969 11,611 — 19,580 Income before income taxes 59,709 66,981 — 126,690 Income tax expense 810 8,089 — 8,899 Net income $ 58,899 $ 58,892 $ — $ 117,791 Capital expenditures $ 342,385 $ 68,551 $ — $ 410,936 Nine Months Ended June 30, 2021 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,715,644 $ 123,462 $ — $ 2,839,106 Intersegment revenues 2,430 353,406 (355,836) — Total operating revenues 2,718,074 476,868 (355,836) 2,839,106 Purchased gas cost 1,304,269 (440) (354,890) 948,939 Operation and maintenance expense 363,246 117,188 (946) 479,488 Depreciation and amortization expense 254,636 98,633 — 353,269 Taxes, other than income 214,991 28,385 — 243,376 Operating income 580,932 233,102 — 814,034 Other non-operating income 1,135 13,658 — 14,793 Interest charges 33,269 35,799 — 69,068 Income before income taxes 548,798 210,961 — 759,759 Income tax expense 109,481 33,435 — 142,916 Net income $ 439,317 $ 177,526 $ — $ 616,843 Capital expenditures $ 1,000,616 $ 357,344 $ — $ 1,357,960 Nine Months Ended June 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,194,786 $ 151,437 $ — $ 2,346,223 Intersegment revenues 2,031 300,984 (303,015) — Total operating revenues 2,196,817 452,421 (303,015) 2,346,223 Purchased gas cost 942,586 290 (302,053) 640,823 Operation and maintenance expense 337,740 112,751 (962) 449,529 Depreciation and amortization expense 229,526 88,556 — 318,082 Taxes, other than income 190,636 23,899 — 214,535 Operating income 496,329 226,925 — 723,254 Other non-operating income 1,930 7,203 — 9,133 Interest charges 35,128 33,852 — 68,980 Income before income taxes 463,131 200,276 — 663,407 Income tax expense 87,411 39,886 — 127,297 Net income $ 375,720 $ 160,390 $ — $ 536,110 Capital expenditures $ 1,119,945 $ 285,728 $ — $ 1,405,673 Balance sheet information at June 30, 2021 and September 30, 2020 by segment is presented in the following tables: June 30, 2021 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 10,802,062 $ 3,675,687 $ — $ 14,477,749 Total assets $ 18,563,345 $ 3,906,816 $ (3,154,726) $ 19,315,435 September 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 9,944,978 $ 3,410,369 $ — $ 13,355,347 Total assets $ 14,578,176 $ 3,647,907 $ (2,867,051) $ 15,359,032

Earnings Per Share (Table)

Earnings Per Share (Table)	9 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted earnings per share for the three and nine months ended June 30, 2021 and 2020 are calculated as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 102,411 $ 117,791 $ 616,843 $ 536,110 Less: Income allocated to participating securities 70 88 440 408 Income available to common shareholders $ 102,341 $ 117,703 $ 616,403 $ 535,702 Basic weighted average shares outstanding 131,358 123,026 129,185 122,352 Net income per share — Basic $ 0.78 $ 0.96 $ 4.77 $ 4.38 Diluted Earnings Per Share Income available to common shareholders $ 102,341 $ 117,703 $ 616,403 $ 535,702 Effect of dilutive shares — — — — Income available to common shareholders $ 102,341 $ 117,703 $ 616,403 $ 535,702 Basic weighted average shares outstanding 131,358 123,026 129,185 122,352 Dilutive shares 128 6 44 111 Diluted weighted average shares outstanding 131,486 123,032 129,229 122,463 Net income per share - Diluted $ 0.78 $ 0.96 $ 4.77 $ 4.37

Revenue and Accounts Receivab_2

Revenue and Accounts Receivable (Table)	9 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables disaggregate our revenue from contracts with customers by customer type and segment and provide a reconciliation to total operating revenues, including intersegment revenues, for the three and nine months ended June 30, 2021 and 2020. Three Months Ended June 30, 2021 Three Months Ended June 30, 2020 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 336,016 $ — $ 286,937 $ — Commercial 157,314 — 101,055 — Industrial 25,348 — 17,019 — Public authority and other 8,870 — 7,063 — Total gas sales revenues 527,548 — 412,074 — Transportation revenues 25,903 164,619 22,532 164,675 Miscellaneous revenues 2,615 3,895 2,793 2,277 Revenues from contracts with customers 556,066 168,514 437,399 166,952 Alternative revenue program revenues (1) 2,206 (5,527) (2,567) (8,944) Other revenues 478 — 476 — Total operating revenues $ 558,750 $ 162,987 $ 435,308 $ 158,008 Nine Months Ended June 30, 2021 Nine Months Ended June 30, 2020 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 1,821,570 $ — $ 1,435,328 $ — Commercial 692,443 — 543,148 — Industrial 81,122 — 67,572 — Public authority and other 42,159 — 34,747 — Total gas sales revenues 2,637,294 — 2,080,795 — Transportation revenues 84,643 480,945 77,676 471,433 Miscellaneous revenues 8,336 12,921 16,565 8,767 Revenues from contracts with customers 2,730,273 493,866 2,175,036 480,200 Alternative revenue program revenues (1) (13,666) (16,998) 20,320 (27,779) Other revenues 1,467 — 1,461 — Total operating revenues $ 2,718,074 $ 476,868 $ 2,196,817 $ 452,421 (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 we share with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a regulatorily determined revenue benchmark.
Allowance for Credit Loss Activity	Rollforwards of our allowance for uncollectible accounts for the three and nine months ended June 30, 2021 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 78 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 June 30, 2021 (In thousands) Beginning balance, March 31, 2021 $ 44,680 Current period provisions 14,403 Write-offs charged against allowance (2,875) Recoveries of amounts previously written off 437 Ending balance, June 30, 2021 $ 56,645 Nine Months Ended June 30, 2021 (In thousands) Beginning balance, September 30, 2020 $ 29,949 Current period provisions 32,872 Write-offs charged against allowance (7,544) Recoveries of amounts previously written off 1,368 Ending balance, June 30, 2021 $ 56,645

Debt (Table)

Debt (Table)	9 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt at June 30, 2021 and September 30, 2020 consisted of the following: June 30, 2021 September 30, 2020 (In thousands) Unsecured 0.625% Senior Notes, due 2023 $ 1,100,000 $ — Unsecured 3.00% Senior Notes, due 2027 500,000 500,000 Unsecured 2.625% Senior Notes, due 2029 300,000 300,000 Unsecured 1.50% Senior Notes, due 2031 600,000 — Unsecured 5.95% Senior Notes, due 2034 200,000 200,000 Unsecured 5.50% Senior Notes, due 2041 400,000 400,000 Unsecured 4.15% Senior Notes, due 2043 500,000 500,000 Unsecured 4.125% Senior Notes, due 2044 750,000 750,000 Unsecured 4.30% Senior Notes, due 2048 600,000 600,000 Unsecured 4.125% Senior Notes, due 2049 450,000 450,000 Unsecured 3.375% Senior Notes, due 2049 500,000 500,000 Floating-rate term loan, due April 2022 200,000 200,000 Floating-rate Senior Notes, due 2023 1,100,000 — Medium-term note Series A, 1995-1, 6.67%, due 2025 10,000 10,000 Unsecured 6.75% Debentures, due 2028 150,000 150,000 Finance lease obligations 18,844 8,631 Total long-term debt 7,378,844 4,568,631 Less: Original issue discount on unsecured senior notes and debentures 2,920 583 Debt issuance cost 46,977 36,104 Current maturities 200,442 165 $ 7,128,505 $ 4,531,779

Shareholders' Equity (Table)

Shareholders' Equity (Table)	9 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Reconciliation of Changes in Stockholders Equity	The following tables present a reconciliation of changes in stockholders' equity for the three and nine months ended June 30, 2021 and 2020. Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2020 125,882,477 $ 629 $ 4,377,149 $ (57,589) $ 2,471,014 $ 6,791,203 Net income — — — — 217,678 217,678 Other comprehensive income — — — 60,121 — 60,121 Cash dividends ($0.625 per share) — — — — (79,023) (79,023) Common stock issued: Public and other stock offerings 2,126,118 11 219,998 — — 220,009 Stock-based compensation plans 144,366 1 3,167 — — 3,168 Balance, December 31, 2020 128,152,961 641 4,600,314 2,532 2,609,669 7,213,156 Net income — — — — 296,754 296,754 Other comprehensive income — — — 137,939 — 137,939 Cash dividends ($0.625 per share) — — — — (80,325) (80,325) Common stock issued: Public and other stock offerings 2,498,026 12 248,948 — — 248,960 Stock-based compensation plans 16,122 — 4,441 — — 4,441 Balance, March 31, 2021 130,667,109 653 4,853,703 140,471 2,826,098 7,820,925 Net income — — — — 102,411 102,411 Other comprehensive loss — — — (79,232) — (79,232) Cash dividends ($0.625 per share) — — — — (81,912) (81,912) Common stock issued: Public and other stock offerings 39,078 1 3,829 — — 3,830 Stock-based compensation plans 80,852 — 7,736 — — 7,736 Balance, June 30, 2021 130,787,039 $ 654 $ 4,865,268 $ 61,239 $ 2,846,597 $ 7,773,758 Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2019 119,338,925 $ 597 $ 3,712,194 $ (114,583) $ 2,152,015 $ 5,750,223 Net income — — — — 178,673 178,673 Other comprehensive income — — — 1,052 — 1,052 Cash dividends ($0.575 per share) — — — — (69,557) (69,557) Common stock issued: Public and other stock offerings 2,758,929 13 263,259 — — 263,272 Stock-based compensation plans 164,549 1 4,111 — — 4,112 Balance, December 31, 2019 122,262,403 611 3,979,564 (113,531) 2,261,131 6,127,775 Net income — — — — 239,646 239,646 Other comprehensive income — — — 890 — 890 Cash dividends ($0.575 per share) — — — — (70,520) (70,520) Common stock issued: Public and other stock offerings 38,662 1 3,095 — — 3,096 Stock-based compensation plans 7,660 — 3,528 — — 3,528 Balance, March 31, 2020 122,308,725 612 3,986,187 (112,641) 2,430,257 6,304,415 Net income — — — — 117,791 117,791 Other comprehensive loss — — — (4,086) — (4,086) Cash dividends ($0.575 per share) — — — — (70,597) (70,597) Common stock issued: Public and other stock offerings 965,576 5 105,799 — — 105,804 Stock-based compensation plans 76,966 — 8,144 — — 8,144 Balance, June 30, 2020 123,351,267 $ 617 $ 4,100,130 $ (116,727) $ 2,477,451 $ 6,461,471
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, 2020 $ 238 $ (57,827) $ (57,589) Other comprehensive income (loss) before reclassifications (165) 115,568 115,403 Amounts reclassified from accumulated other comprehensive income — 3,425 3,425 Net current-period other comprehensive income (loss) (165) 118,993 118,828 June 30, 2021 $ 73 $ 61,166 $ 61,239 Available- Interest Rate Total (In thousands) September 30, 2019 $ 132 $ (114,715) $ (114,583) Other comprehensive income (loss) before reclassifications 202 (4,932) (4,730) Amounts reclassified from accumulated other comprehensive income (2) 2,588 2,586 Net current-period other comprehensive income (loss) 200 (2,344) (2,144) June 30, 2020 $ 332 $ (117,059) $ (116,727)

Interim Pension and Other Pos_2

Interim Pension and Other Postretirement Benefit Plan Information (Table)	9 Months Ended
	Jun. 30, 2021
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 nine months ended June 30, 2021 and 2020 are presented in the following tables. Most of these costs are recoverable through our tariff rates. A portion of these costs is capitalized into our rate base or deferred as a regulatory asset or liability. The remaining costs are recorded as a component of operation and maintenance expense or other non-operating expense. In the third quarter of fiscal 2021, due to the retirement of certain executives, we recognized a settlement charge of $9.0 million associated with our Supplemental Executive Retirement Plan and revalued the net periodic pension cost for the remainder of fiscal 2021. The revaluation of the net periodic pension cost for our Supplemental Executive Retirement Plan resulted in an increase in the discount rate, effective May 31, 2021, to 3.11% from 2.80%, which will decrease our net periodic pension cost by approximately $0.5 million for the remainder of the fiscal year. Three Months Ended June 30 Pension Benefits Other Benefits 2021 2020 2021 2020 (In thousands) Components of net periodic pension cost: Service cost $ 4,609 $ 4,652 $ 4,305 $ 3,366 Interest cost (1) 5,016 5,843 2,661 2,653 Expected return on assets (1) (6,978) (7,079) (2,613) (2,625) Amortization of prior service cost (credit) (1) (58) (58) 44 43 Amortization of actuarial (gain) loss (1) 3,062 3,242 — (334) Settlements (1) 8,999 — — — Net periodic pension cost $ 14,650 $ 6,600 $ 4,397 $ 3,103 Nine Months Ended June 30 Pension Benefits Other Benefits 2021 2020 2021 2020 (In thousands) Components of net periodic pension cost: Service cost $ 13,834 $ 13,957 $ 12,917 $ 10,099 Interest cost (1) 15,072 17,529 7,981 7,959 Expected return on assets (1) (20,934) (21,237) (7,841) (7,874) Amortization of prior service cost (credit) (1) (174) (174) 130 130 Amortization of actuarial (gain) loss (1) 9,405 9,725 — (1,003) Settlements (1) 8,999 — — — Net periodic pension cost $ 26,202 $ 19,800 $ 13,187 $ 9,311 (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, 2020.

Financial Instruments (Table)

Financial Instruments (Table)	9 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivatives	The following table summarizes our existing forward starting interest rate swaps as of June 30, 2021: Planned Debt Issuance Date Amount Hedged Effective Interest Rate (In thousands) Fiscal 2022 $ 600,000 1.53 % Fiscal 2023 400,000 1.56 % Fiscal 2024 75,000 2.19 % Fiscal 2025 400,000 1.56 % Fiscal 2026 100,000 2.21 % $ 1,575,000
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following tables present the fair value and balance sheet classification of our financial instruments as of June 30, 2021 and September 30, 2020. 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, for June 30, 2021 and September 30, 2020, no gross amounts and no cash collateral were netted within our consolidated balance sheet. Balance Sheet Location Assets Liabilities (In thousands) June 30, 2021 Designated As Hedges: Interest rate contracts Other current assets / $ 89,260 $ (2,902) Interest rate contracts Deferred charges and other assets / 136,242 (574) Total 225,502 (3,476) Not Designated As Hedges: Commodity contracts Other current assets / 12,024 (1,926) Commodity contracts Deferred charges and other assets / 1,393 — Total 13,417 (1,926) Gross / Net Financial Instruments $ 238,919 $ (5,402) Balance Sheet Location Assets Liabilities (In thousands) September 30, 2020 Designated As Hedges: Interest rate contracts Deferred charges and other assets / $ 73,055 $ — Total 73,055 — Not Designated As Hedges: Commodity contracts Other current assets / 5,687 (2,015) Commodity contracts Deferred charges and other assets / 1,936 — Total 7,623 (2,015) Gross / Net Financial Instruments $ 80,678 $ (2,015)
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)	The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and nine months ended June 30, 2021 and 2020. The amounts included in the table below exclude gains and losses arising from ineffectiveness because those amounts are immediately recognized in the statement of comprehensive income as incurred. Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (80,338) $ (4,932) $ 115,568 $ (4,932) Recognition of losses in earnings due to settlements: Interest rate agreements 1,142 482 3,425 2,588 Total other comprehensive income (loss) from hedging, net of tax $ (79,196) $ (4,450) $ 118,993 $ (2,344)
Schedule of Expected Deferred Gains (Losses) Recognition	The following amounts, net of deferred taxes, represent the expected recognition in earnings of the deferred net losses 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 2049. 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 $ (4,566) Thereafter (106,511) Total $ (111,077)

Fair Value Measurements (Table)

Fair Value Measurements (Table)	9 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of June 30, 2021 and September 30, 2020. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and June 30, 2021 (In thousands) Assets: Financial instruments $ — $ 238,919 $ — $ — $ 238,919 Debt and equity securities Registered investment companies 35,166 — — — 35,166 Bond mutual funds 34,270 — — — 34,270 Bonds (2) — 32,264 — — 32,264 Money market funds — 4,017 — — 4,017 Total debt and equity securities 69,436 36,281 — — 105,717 Total assets $ 69,436 $ 275,200 $ — $ — $ 344,636 Liabilities: Financial instruments $ — $ 5,402 $ — $ — $ 5,402 Quoted Significant Other Observable Inputs (Level 2) (1) Significant Netting and September 30, 2020 (In thousands) Assets: Financial instruments $ — $ 80,678 $ — $ — $ 80,678 Debt and equity securities Registered investment companies 37,831 — — — 37,831 Bond mutual funds 29,166 — — — 29,166 Bonds (2) — 32,900 — — 32,900 Money market funds — 4,055 — — 4,055 Total debt and equity securities 66,997 36,955 — — 103,952 Total assets $ 66,997 $ 117,633 $ — $ — $ 184,630 Liabilities: Financial instruments $ — $ 2,015 $ — $ — $ 2,015 (1) Our Level 2 measurements consist of over-the-counter options and swaps, which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds, which are valued based on the most recent available quoted market prices and money market funds that are valued at cost. (2) Our investments in bonds are considered available-for-sale debt securities in accordance with current accounting guidance.
Schedule of Carrying Values and Estimated Fair Values of Long-Term Debt	The following table presents the carrying value and fair value of our long-term debt, excluding finance leases, debt issuance costs and original issue premium or discount, as of June 30, 2021 and September 30, 2020: June 30, 2021 September 30, 2020 (In thousands) Carrying Amount $ 7,360,000 $ 4,560,000 Fair Value $ 8,101,744 $ 5,597,183

Nature of Business (Details)

Nature of Business (Details) customer in Millions	Jun. 30, 2021statecustomerregulated_distribution_division
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of customers serviced | customer	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	Jun. 30, 2021	Sep. 30, 2020
Regulatory Asset [Line Items]
Regulatory assets	$ 2,527,012	$ 414,641
Regulatory Liabilities [Line Items]
Regulatory liabilities	1,362,984	1,367,013
Regulatory excess deferred taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	694,018	718,651
Regulatory cost of removal obligation
Regulatory Liabilities [Line Items]
Regulatory liabilities	536,317	531,096
Deferred gas costs
Regulatory Liabilities [Line Items]
Regulatory liabilities	55,572	19,985
Asset retirement obligation
Regulatory Liabilities [Line Items]
Regulatory liabilities	20,348	20,348
APT annual adjustment mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities	37,358	57,379
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	19,371	19,554
Pension and postretirement benefit costs
Regulatory Asset [Line Items]
Regulatory assets	135,411	149,089
Infrastructure mechanisms
Regulatory Asset [Line Items]
Regulatory assets	222,263	183,943
Winter Storm Uri incremental costs
Regulatory Asset [Line Items]
Regulatory assets	2,093,779	0
Deferred gas costs
Regulatory Asset [Line Items]
Regulatory assets	27,593	40,593
Regulatory excess deferred taxes
Regulatory Asset [Line Items]
Regulatory assets	8,838	0
Recoverable loss on reacquired debt
Regulatory Asset [Line Items]
Regulatory assets	3,893	4,894
Deferred pipeline record collection costs
Regulatory Asset [Line Items]
Regulatory assets	31,283	29,839
Other
Regulatory Asset [Line Items]
Regulatory assets	$ 3,952	$ 6,283

Unaudited Financial Informati_5

Unaudited Financial Information - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,362,984		$ 1,367,013
Effective income tax rate	18.80%	19.20%
Regulatory excess deferred taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 694,018		718,651
Regulatory excess deferred taxes, to be returned, tranche one
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 243,000
Regulatory excess deferred taxes, to be returned, tranche one | Minimum
Regulatory Liabilities [Line Items]
Return basis, term	35 months
Regulatory excess deferred taxes, to be returned, tranche one | Maximum
Regulatory Liabilities [Line Items]
Return basis, term	60 months
Regulatory excess deferred taxes, to be returned, tranche two
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 430,100
Regulatory excess deferred taxes, to be returned, tranche two | Minimum
Regulatory Liabilities [Line Items]
Return basis, term	15 years
Regulatory excess deferred taxes, to be returned, tranche two | Maximum
Regulatory Liabilities [Line Items]
Return basis, term	69 years
Regulatory excess deferred taxes, to be returned, tranche three
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 12,100
Other Current Liabilities | Regulatory excess deferred taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 106,300		$ 20,900

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2021USD ($)state	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jun. 30, 2021USD ($)state	Jun. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Segment Reporting Information [Line Items]
Number of states with service areas | state	8						8
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	$ 605,553			$ 492,995			$ 2,839,106	$ 2,346,223
Purchased gas cost	86,870			26,072			948,939	640,823
Operation and maintenance expense	184,470			149,460			479,488	449,529
Depreciation and amortization expense	119,348			107,104			353,269	318,082
Taxes, other than income	81,475			71,324			243,376	214,535
Operating income	133,390			139,035			814,034	723,254
Other non-operating income	5,887			7,235			14,793	9,133
Interest charges	20,962			19,580			69,068	68,980
Income before income taxes	118,315			126,690			759,759	663,407
Income tax expense	15,904			8,899			142,916	127,297
Net income	102,411	$ 296,754	$ 217,678	117,791	$ 239,646	$ 178,673	616,843	536,110
Capital expenditures	512,232			410,936			1,357,960	1,405,673
Segment Reporting Information, Balance Sheet [Abstract]
Property, plant and equipment, net	14,477,749						14,477,749		$ 13,355,347
Total assets	19,315,435						19,315,435		15,359,032
Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	557,931			434,650			2,715,644	2,194,786
Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	47,622			58,345			123,462	151,437
Operating Segments | Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	558,750			435,308			2,718,074	2,196,817
Purchased gas cost	202,050			126,093			1,304,269	942,586
Operation and maintenance expense	130,454			107,537			363,246	337,740
Depreciation and amortization expense	86,099			77,187			254,636	229,526
Taxes, other than income	72,024			61,980			214,991	190,636
Operating income	68,123			62,511			580,932	496,329
Other non-operating income	1,060			5,167			1,135	1,930
Interest charges	8,540			7,969			33,269	35,128
Income before income taxes	60,643			59,709			548,798	463,131
Income tax expense	7,354			810			109,481	87,411
Net income	53,289			58,899			439,317	375,720
Capital expenditures	398,416			342,385			1,000,616	1,119,945
Segment Reporting Information, Balance Sheet [Abstract]
Property, plant and equipment, net	10,802,062						10,802,062		9,944,978
Total assets	18,563,345						18,563,345		14,578,176
Operating Segments | Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	162,987			158,008			476,868	452,421
Purchased gas cost	691			(11)			(440)	290
Operation and maintenance expense	54,329			42,234			117,188	112,751
Depreciation and amortization expense	33,249			29,917			98,633	88,556
Taxes, other than income	9,451			9,344			28,385	23,899
Operating income	65,267			76,524			233,102	226,925
Other non-operating income	4,827			2,068			13,658	7,203
Interest charges	12,422			11,611			35,799	33,852
Income before income taxes	57,672			66,981			210,961	200,276
Income tax expense	8,550			8,089			33,435	39,886
Net income	49,122			58,892			177,526	160,390
Capital expenditures	113,816			68,551			357,344	285,728
Segment Reporting Information, Balance Sheet [Abstract]
Property, plant and equipment, net	3,675,687						3,675,687		3,410,369
Total assets	3,906,816						3,906,816		3,647,907
Eliminations
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	(116,184)			(100,321)			(355,836)	(303,015)
Purchased gas cost	(115,871)			(100,010)			(354,890)	(302,053)
Operation and maintenance expense	(313)			(311)			(946)	(962)
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]
Property, plant and equipment, net	0						0		0
Total assets	(3,154,726)						(3,154,726)		$ (2,867,051)
Eliminations | Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	819			658			2,430	2,031
Eliminations | Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	$ 115,365			$ 99,663			$ 353,406	$ 300,984

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2021	Jun. 30, 2020
Basic Earnings Per Share
Net income	$ 102,411	$ 296,754	$ 217,678	$ 117,791	$ 239,646	$ 178,673	$ 616,843	$ 536,110
Less: Income allocated to participating securities	70			88			440	408
Income available to common shareholders	$ 102,341			$ 117,703			$ 616,403	$ 535,702
Basic weighted average shares outstanding (in shares)	131,358			123,026			129,185	122,352
Net income per share - Basic (USD per share)	$ 0.78			$ 0.96			$ 4.77	$ 4.38
Diluted Earnings Per Share
Income available to common shareholders	$ 102,341			$ 117,703			$ 616,403	$ 535,702
Effect of dilutive shares	0			0			0	0
Income available to common shareholders	$ 102,341			$ 117,703			$ 616,403	$ 535,702
Basic weighted average shares outstanding (in shares)	131,358			123,026			129,185	122,352
Dilutive shares (in shares)	128			6			44	111
Diluted weighted average shares outstanding (in shares)	131,486			123,032			129,229	122,463
Net income per share - Diluted (USD per share)	$ 0.78			$ 0.96			$ 4.77	$ 4.37

Revenue and Accounts Receivab_3

Revenue and Accounts Receivable - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 605,553	$ 492,995	$ 2,839,106	$ 2,346,223
Distribution
Disaggregation of Revenue [Line Items]
Total operating revenues	557,931	434,650	$ 2,715,644	2,194,786
Regulatory mechanism threshold (in percent)			75.00%
Pipeline and Storage
Disaggregation of Revenue [Line Items]
Total operating revenues	47,622	58,345	$ 123,462	151,437
Operating Segments | Distribution
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	556,066	437,399	2,730,273	2,175,036
Alternative revenue program revenues	2,206	(2,567)	(13,666)	20,320
Other revenues	478	476	1,467	1,461
Total operating revenues	558,750	435,308	2,718,074	2,196,817
Operating Segments | Distribution | Gas sales revenues:
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	527,548	412,074	2,637,294	2,080,795
Operating Segments | Distribution | Gas sales revenues: | Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	336,016	286,937	1,821,570	1,435,328
Operating Segments | Distribution | Gas sales revenues: | Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	157,314	101,055	692,443	543,148
Operating Segments | Distribution | Gas sales revenues: | Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	25,348	17,019	81,122	67,572
Operating Segments | Distribution | Gas sales revenues: | Public authority and other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8,870	7,063	42,159	34,747
Operating Segments | Distribution | Transportation revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	25,903	22,532	84,643	77,676
Operating Segments | Distribution | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,615	2,793	8,336	16,565
Operating Segments | Pipeline and Storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	168,514	166,952	493,866	480,200
Alternative revenue program revenues	(5,527)	(8,944)	(16,998)	(27,779)
Other revenues	0	0	0	0
Total operating revenues	162,987	158,008	476,868	452,421
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	164,619	164,675	480,945	471,433
Operating Segments | Pipeline and Storage | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 3,895	$ 2,277	$ 12,921	$ 8,767

Revenue and Accounts Receivab_4

Revenue and Accounts Receivable - Allowance for Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Percent of customers excluded		78.00%
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 44,680	$ 29,949
Current period provisions	14,403	32,872
Write-offs charged against allowance	(2,875)	(7,544)
Recoveries of amounts previously written off	437	1,368
Ending balance	$ 56,645	$ 56,645

Debt - Schedule of Long-term De

Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 09, 2021	Oct. 01, 2020	Sep. 30, 2020
Debt Instrument [Line Items]
Long-term debt	$ 7,360,000			$ 4,560,000
Finance lease obligations	18,844			8,631
Total long-term debt	7,378,844			4,568,631
Less:
Original issue discount on unsecured senior notes and debentures	2,920			583
Debt issuance cost	46,977			36,104
Current maturities	200,442			165
Long-term debt, noncurrent	$ 7,128,505			4,531,779
Unsecured 0.625% Senior Notes, due 2023
Debt Instrument [Line Items]
Interest rate	0.625%	0.625%
Long-term debt	$ 1,100,000			0
Unsecured 3.00% Senior Notes, due 2027
Debt Instrument [Line Items]
Interest rate	3.00%
Long-term debt	$ 500,000			500,000
Unsecured 2.625% Senior Notes, due 2029
Debt Instrument [Line Items]
Interest rate	2.625%
Long-term debt	$ 300,000			300,000
Unsecured 1.50% Senior Notes, due 2031
Debt Instrument [Line Items]
Interest rate	1.50%		1.50%
Long-term debt	$ 600,000			0
Unsecured 5.95% Senior Notes, due 2034
Debt Instrument [Line Items]
Interest rate	5.95%
Long-term debt	$ 200,000			200,000
Unsecured 5.50% Senior Notes, due 2041
Debt Instrument [Line Items]
Interest rate	5.50%
Long-term debt	$ 400,000			400,000
Unsecured 4.15% Senior Notes, due 2043
Debt Instrument [Line Items]
Interest rate	4.15%
Long-term debt	$ 500,000			500,000
Unsecured 4.125% Senior Notes, due 2044
Debt Instrument [Line Items]
Interest rate	4.125%
Long-term debt	$ 750,000			750,000
Unsecured 4.30% Senior Notes, due 2048
Debt Instrument [Line Items]
Interest rate	4.30%
Long-term debt	$ 600,000			600,000
Unsecured 4.125% Senior Notes, due 2049
Debt Instrument [Line Items]
Interest rate	4.125%
Long-term debt	$ 450,000			450,000
Unsecured 3.375% Senior Notes, due 2049
Debt Instrument [Line Items]
Interest rate	3.375%
Long-term debt	$ 500,000			500,000
Floating-rate term loan, due April 2022
Debt Instrument [Line Items]
Long-term debt	200,000			200,000
Floating-rate Senior Notes, due 2023
Debt Instrument [Line Items]
Long-term debt	$ 1,100,000			0
Medium-term note Series A, 1995-1, 6.67%, due 2025
Debt Instrument [Line Items]
Interest rate	6.67%
Long-term debt	$ 10,000			10,000
Unsecured 6.75% Debentures, due 2028
Debt Instrument [Line Items]
Interest rate	6.75%
Long-term debt	$ 150,000			$ 150,000

Debt - Narrative (Details)

Debt - Narrative (Details)	Apr. 29, 2021USD ($)	Apr. 01, 2021USD ($)	Mar. 31, 2021USD ($)credit_facility	Mar. 09, 2021USD ($)	Oct. 01, 2020USD ($)	Mar. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Sep. 30, 2020USD ($)
Line Of Credit Facility [Line Items]
Proceeds from issuance of long-term debt							$ 2,797,346,000	$ 999,450,000
Maximum debt-to-total-capitalization ratio							70.00%
Debt-to-total-capitalization ratio							0.50
Minimum
Line Of Credit Facility [Line Items]
Equity-to-total-capitalization ratio							50.00%
Outstanding indebtedness							$ 15,000,000
Maximum
Line Of Credit Facility [Line Items]
Equity-to-total-capitalization ratio							60.00%
Outstanding indebtedness							$ 100,000,000
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity			$ 2,500,000,000
Number of credit facilities | credit_facility			4
Senior Notes Due 2023
Line Of Credit Facility [Line Items]
Debt instrument, face amount				$ 2,200,000,000
Proceeds net of issuance cost				$ 2,200,000,000
Redemption price (in percent)				100.00%
Unsecured 0.625% Senior Notes, due 2023
Line Of Credit Facility [Line Items]
Debt instrument, face amount				$ 1,100,000,000
Interest rate				0.625%			0.625%
Effective Interest Rate				0.834%
Floating-rate Senior Notes, due 2023
Line Of Credit Facility [Line Items]
Debt instrument, face amount				$ 1,100,000,000
Unsecured 1.50% Senior Notes, due 2031
Line Of Credit Facility [Line Items]
Debt instrument, face amount					$ 600,000,000
Interest rate					1.50%		1.50%
Effective Interest Rate					1.71%
Proceeds from issuance of long-term debt					$ 592,300,000
Five Year Unsecured Revolving Credit Agreement
Line Of Credit Facility [Line Items]
Outstanding commercial paper							$ 0		$ 0
Five Year Unsecured Revolving Credit Agreement | Commercial Paper
Line Of Credit Facility [Line Items]
Maximum borrowing capacity			$ 1,500,000,000			$ 1,500,000,000
Debt agreement term			5 years			5 years
Accordion feature							250,000,000
Maximum borrowing capacity post accordion feature							1,750,000,000
$600 Million Revolving Credit Facility | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity						$ 600,000,000
Debt agreement term						364 days
$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
$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
$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
LIBOR | Floating-rate Senior Notes, due 2023
Line Of Credit Facility [Line Items]
Interest rate spread				0.38%
LIBOR | Five Year Unsecured Revolving Credit Agreement | Minimum
Line Of Credit Facility [Line Items]
Interest rate spread			0.00%
LIBOR | Five Year Unsecured Revolving Credit Agreement | Maximum
Line Of Credit Facility [Line Items]
Interest rate spread			0.25%
LIBOR | $900 Million Revolving Credit Facility | Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Interest rate spread			0.75%
LIBOR | $900 Million Revolving Credit Facility | Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Interest rate spread			1.25%
Base Rate | Five Year Unsecured Revolving Credit Agreement | Minimum
Line Of Credit Facility [Line Items]
Interest rate spread			0.75%
Base Rate | Five Year Unsecured Revolving Credit Agreement | Maximum
Line Of Credit Facility [Line Items]
Interest rate spread			1.25%
Base Rate | $900 Million Revolving Credit Facility | Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Interest rate spread			0.00%
Base Rate | $900 Million Revolving Credit Facility | Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Interest rate spread			0.25%

Shareholders' Equity - Componen

Shareholders' Equity - Components of Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2021	Jun. 30, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)			125,882,477				125,882,477
Shareholders' equity, beginning balance	$ 7,820,925	$ 7,213,156	$ 6,791,203	$ 6,304,415	$ 6,127,775	$ 5,750,223	$ 6,791,203	$ 5,750,223
Net income	102,411	296,754	217,678	117,791	239,646	178,673	616,843	536,110
Other comprehensive income (loss)	(79,232)	137,939	60,121	(4,086)	890	1,052	$ 118,828	(2,144)
Cash dividends	(81,912)	(80,325)	(79,023)	(70,597)	(70,520)	(69,557)
Public and other stock offerings	3,830	248,960	220,009	105,804	3,096	263,272
Stock-based compensation plans	$ 7,736	4,441	3,168	8,144	3,528	4,112
Common stock outstanding, ending balance (in shares)	130,787,039						130,787,039
Shareholders' equity, ending balance	$ 7,773,758	$ 7,820,925	$ 7,213,156	$ 6,461,471	$ 6,304,415	$ 6,127,775	$ 7,773,758	$ 6,461,471
Cash dividends per share (USD per share)	$ 0.625	$ 0.625	$ 0.625	$ 0.575	$ 0.575	$ 0.575	$ 1.875	$ 1.725
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding, beginning balance (in shares)	130,667,109	128,152,961	125,882,477	122,308,725	122,262,403	119,338,925	125,882,477	119,338,925
Shareholders' equity, beginning balance	$ 653	$ 641	$ 629	$ 612	$ 611	$ 597	$ 629	$ 597
Public and other stock offerings (in shares)	39,078	2,498,026	2,126,118	965,576	38,662	2,758,929
Public and other stock offerings	$ 1	$ 12	$ 11	$ 5	$ 1	$ 13
Stock-based compensation plans (in shares)	80,852	16,122	144,366	76,966	7,660	164,549
Stock-based compensation plans	$ 0	$ 0	$ 1	$ 0	$ 0	$ 1
Common stock outstanding, ending balance (in shares)	130,787,039	130,667,109	128,152,961	123,351,267	122,308,725	122,262,403	130,787,039	123,351,267
Shareholders' equity, ending balance	$ 654	$ 653	$ 641	$ 617	$ 612	$ 611	$ 654	$ 617
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	4,853,703	4,600,314	4,377,149	3,986,187	3,979,564	3,712,194	4,377,149	3,712,194
Public and other stock offerings	3,829	248,948	219,998	105,799	3,095	263,259
Stock-based compensation plans	7,736	4,441	3,167	8,144	3,528	4,111
Shareholders' equity, ending balance	4,865,268	4,853,703	4,600,314	4,100,130	3,986,187	3,979,564	4,865,268	4,100,130
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	140,471	2,532	(57,589)	(112,641)	(113,531)	(114,583)	(57,589)	(114,583)
Other comprehensive income (loss)	(79,232)	137,939	60,121	(4,086)	890	1,052
Shareholders' equity, ending balance	61,239	140,471	2,532	(116,727)	(112,641)	(113,531)	61,239	(116,727)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	2,826,098	2,609,669	2,471,014	2,430,257	2,261,131	2,152,015	2,471,014	2,152,015
Net income	102,411	296,754	217,678	117,791	239,646	178,673
Cash dividends	(81,912)	(80,325)	(79,023)	(70,597)	(70,520)	(69,557)
Shareholders' equity, ending balance	$ 2,846,597	$ 2,826,098	$ 2,609,669	$ 2,477,451	$ 2,430,257	$ 2,261,131	$ 2,846,597	$ 2,477,451

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details) - USD ($)	9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 29, 2021
Class of Stock [Line Items]
Net proceeds available	$ 213,100,000
Net proceeds from equity offering	$ 460,678,000	$ 358,047,000
Forward Price (dollars per share)	$ 94.71
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]
Net proceeds available	$ 338,300,000
Forward sales equity agreement (in shares)	3,451,356
Stock issued during period, new issues (in shares)	4,537,669
Net proceeds from equity offering	$ 460,700,000
Equity available for issuance	$ 1,000,000,000		$ 1,000,000,000

Shareholders' Equity - Schedule

Shareholders' Equity - Schedule of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	$ 7,820,925	$ 7,213,156	$ 6,791,203	$ 6,304,415	$ 6,127,775	$ 5,750,223	$ 6,791,203	$ 5,750,223
Other comprehensive income (loss) before reclassifications							115,403	(4,730)
Amounts reclassified from accumulated other comprehensive income							3,425	2,586
Net current-period other comprehensive income (loss)	(79,232)	137,939	60,121	(4,086)	890	1,052	118,828	(2,144)
Shareholders' equity, ending balance	7,773,758	7,820,925	7,213,156	6,461,471	6,304,415	6,127,775	7,773,758	6,461,471
Available- for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance			238			132	238	132
Other comprehensive income (loss) before reclassifications							(165)	202
Amounts reclassified from accumulated other comprehensive income							0	(2)
Net current-period other comprehensive income (loss)							(165)	200
Shareholders' equity, ending balance	73			332			73	332
Interest Rate Agreement Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance			(57,827)			(114,715)	(57,827)	(114,715)
Other comprehensive income (loss) before reclassifications							115,568	(4,932)
Amounts reclassified from accumulated other comprehensive income							3,425	2,588
Net current-period other comprehensive income (loss)							118,993	(2,344)
Shareholders' equity, ending balance	61,166			(117,059)			61,166	(117,059)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	140,471	2,532	(57,589)	(112,641)	(113,531)	(114,583)	(57,589)	(114,583)
Net current-period other comprehensive income (loss)	(79,232)	137,939	60,121	(4,086)	890	1,052
Shareholders' equity, ending balance	$ 61,239	$ 140,471	$ 2,532	$ (116,727)	$ (112,641)	$ (113,531)	$ 61,239	$ (116,727)

Interim Pension and Other Pos_3

Interim Pension and Other Postretirement Benefit Plan Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	May 31, 2021	May 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Settlements		$ (9,000)
Contribution to postretirement medical plans				$ 16,800
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (in percent)						3.11%	2.80%
Service cost		4,609	$ 4,652	13,834	$ 13,957
Interest cost		5,016	5,843	15,072	17,529
Expected return on assets		(6,978)	(7,079)	(20,934)	(21,237)
Amortization of prior service cost (credit)		(58)	(58)	(174)	(174)
Amortization of actuarial (gain) loss		3,062	3,242	9,405	9,725
Settlements		8,999	0	8,999	0
Net periodic pension cost		14,650	6,600	26,202	19,800
Pension Benefits | Forecast
Defined Benefit Plan Disclosure [Line Items]
Decrease in net periodic pension cost	$ 500
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost		4,305	3,366	12,917	10,099
Interest cost		2,661	2,653	7,981	7,959
Expected return on assets		(2,613)	(2,625)	(7,841)	(7,874)
Amortization of prior service cost (credit)		44	43	130	130
Amortization of actuarial (gain) loss		0	(334)	0	(1,003)
Settlements		0	0	0	0
Net periodic pension cost		4,397	$ 3,103	13,187	$ 9,311
Minimum | Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions		15,000		15,000
Maximum | Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions		$ 25,000		$ 25,000

Commitments and Contingencies (

Commitments and Contingencies (Details)	Feb. 08, 2021USD ($)	Jun. 30, 2021USD ($)Bcf
Long-term Purchase Commitment [Line Items]
Self-insured retention | $		$ 1,000,000
Penalties incurred | $	$ 1,600,000
Short-term Contract with Customer | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, minimum volume required | Bcf		54.3
Contract term		1 year
Long-term Contract with Customer Within Two To Three Years | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, minimum volume required | Bcf		17,600
Long-term Contract with Customer Within Two To Three Years | Supply Commitment | Maximum
Long-term Purchase Commitment [Line Items]
Contract term		3 years
Long-term Contract with Customer Within Two To Three Years | Supply Commitment | Minimum
Long-term Purchase Commitment [Line Items]
Contract term		2 years

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)Bcf	Jun. 30, 2020USD ($)	Jul. 31, 2021USD ($)	Sep. 30, 2020USD ($)
Derivative [Line Items]
Contract netting	$ 0		$ 0			$ 0
Cash collateral	0		0			$ 0
Net gain (loss) on settled interest rate agreements	(1,500,000)	$ (1,400,000)	(4,400,000)	$ (4,100,000)
Net realized gain (loss) in AOCI	(111,100,000)		(111,100,000)
Designated As Hedges: | Forward Interest Rate Swap 1
Derivative [Line Items]
Amount Hedged	$ 525,000,000		$ 525,000,000
Designated As Hedges: | Forward Interest Rate Swap 1 | Subsequent Event
Derivative [Line Items]
Amount Hedged					$ 875,000,000
Gas Purchases | Not Designated As Hedges: | Commodity contracts
Derivative [Line Items]
Hedging percent	39.00%		39.00%
Energy measure | Bcf			15.8
Gas Purchases | Not Designated As Hedges: | Commodity contracts | Long
Derivative [Line Items]
Energy measure | Bcf			16.80
Minimum | Gas Purchases | Not Designated As Hedges: | Commodity contracts
Derivative [Line Items]
Hedging percent	25.00%		25.00%
Maximum | Gas Purchases | Not Designated As Hedges: | Commodity contracts
Derivative [Line Items]
Hedging percent	50.00%		50.00%

Financial Instruments - Forward

Financial Instruments - Forward Starting Derivatives (Details) - Designated As Hedges: - Forward Interest Rate Swap	Jun. 30, 2021USD ($)
Derivative [Line Items]
Amount Hedged	$ 1,575,000,000
Unsecured Senior Notes In Fiscal 2022
Derivative [Line Items]
Amount Hedged	$ 600,000,000
Effective Interest Rate	1.53%
Unsecured Senior Notes In Fiscal 2023
Derivative [Line Items]
Amount Hedged	$ 400,000,000
Effective Interest Rate	1.56%
Unsecured Senior Notes In Fiscal 2024
Derivative [Line Items]
Amount Hedged	$ 75,000,000
Effective Interest Rate	2.19%
Unsecured Senior Notes In Fiscal 2025
Derivative [Line Items]
Amount Hedged	$ 400,000,000
Effective Interest Rate	1.56%
Unsecured Senior Notes In Fiscal 2026
Derivative [Line Items]
Amount Hedged	$ 100,000,000
Effective Interest Rate	2.21%

Financial Instruments - Schedul

Financial Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Derivatives Fair Value [Line Items]
Net Financial Instruments, Assets	$ 238,919	$ 80,678
Net Financial Instruments, Liabilities	(5,402)	(2,015)
Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	225,502	73,055
Gross Financial Instruments, Liabilities	(3,476)	0
Designated As Hedges: | Other current assets | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	89,260
Designated As Hedges: | Other current liabilities | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	(2,902)
Designated As Hedges: | Deferred charges and other assets | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	136,242	73,055
Designated As Hedges: | Deferred credits and other liabilities | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	(574)	0
Not Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	13,417	7,623
Gross Financial Instruments, Liabilities	(1,926)	(2,015)
Not Designated As Hedges: | Other current assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	12,024	5,687
Not Designated As Hedges: | Other current liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	(1,926)	(2,015)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	1,393	1,936
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	$ 0	$ 0

Financial Instruments - Sched_2

Financial Instruments - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Increase (decrease) in fair value:
Interest rate agreements	$ (80,338)	$ (4,932)	$ 115,568	$ (4,932)
Recognition of losses in earnings due to settlements:
Interest rate agreements	1,142	482	3,425	2,588
Total other comprehensive income (loss) from hedging, net of tax	$ (79,196)	$ (4,450)	$ 118,993	$ (2,344)

Financial Instruments - Sched_3

Financial Instruments - Schedule Of Expected Deferred Gains (Losses) Recognition (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2021USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Next twelve months	$ (4,566)
Thereafter	(106,511)
Total	$ (111,077)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Jun. 30, 2021	Sep. 30, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Netting and Cash Collateral	$ 0	$ 0
Financial instruments net assets	238,919,000	80,678,000
Debt and equity securities	105,717,000	103,952,000
Total assets	344,636,000	184,630,000
Netting and Cash Collateral	0	0
Financial instruments net liability	5,402,000	2,015,000
Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	35,166,000	37,831,000
Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	34,270,000	29,166,000
Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	32,264,000	32,900,000
Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	4,017,000	4,055,000
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	69,436,000	66,997,000
Total assets	69,436,000	66,997,000
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	35,166,000	37,831,000
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	34,270,000	29,166,000
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	238,919,000	80,678,000
Debt and equity securities	36,281,000	36,955,000
Total assets	275,200,000	117,633,000
Financial instruments gross liability	5,402,000	2,015,000
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	32,264,000	32,900,000
Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	4,017,000	4,055,000
Significant Other Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial instruments gross assets	0	0
Debt and equity securities	0	0
Total assets	0	0
Financial instruments gross liability	0	0
Significant Other Unobservable Inputs (Level 3) | Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	0	0
Significant Other Unobservable Inputs (Level 3) | Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	0	0
Significant Other Unobservable Inputs (Level 3) | Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	0	0
Significant Other Unobservable Inputs (Level 3) | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	Jun. 30, 2021	Sep. 30, 2020
Schedule of Available For Sale Securities [Abstract]
Allowance for credit losses	$ 0
Cost basis	$ 32,200,000	$ 32,600,000

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Carrying Amount	$ 7,360,000	$ 4,560,000
Fair Value	$ 8,101,744	$ 5,597,183

Winter Storm Uri (Details)

Winter Storm Uri (Details) - USD ($)	1 Months Ended	9 Months Ended
	Feb. 28, 2021	Jun. 30, 2021	Mar. 09, 2021	Sep. 30, 2020
Unusual or Infrequent Item, or Both [Line Items]
Aggregate natural gas purchases	$ 2,300,000,000
Regulatory assets		$ 2,527,012,000		$ 414,641,000
Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Increase (decrease) in net operating loss carryforwards		469,400,000
Increase (decrease) in deferred income taxes		469,400,000
Federal net operating loss carryforward		804,700,000
State net operating loss carryforward		57,000,000
State net operating loss carryforward, federal effects		15,200,000
State tax credit carryforwards		1,800,000
State tax credit carryforwards, federal effects		500,000
Winter Storm Uri incremental costs
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		2,093,779,000		$ 0
Winter Storm Uri incremental costs | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		2,100,000,000
Winter Storm Uri incremental costs | Kansas | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		77,100,000
Winter Storm Uri incremental costs | Texas | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		2,016,700,000
Extraordinary Gas Cost | Winter Storm Uri
Unusual or Infrequent Item, or Both [Line Items]
Regulatory assets		$ 2,000,000,000
Senior Notes Due 2023
Unusual or Infrequent Item, or Both [Line Items]
Debt instrument, face amount			$ 2,200,000,000