Atmos Energy (ATO) 10-Q 5 Aug 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Jun. 30, 2020	Jul. 31, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
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)		123,354,982
Entity Central Index Key	0000731802
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
ASSETS
Property, plant and equipment	$ 15,443,224	$ 14,180,593
Less accumulated depreciation and amortization	2,562,374	2,392,924
Net property, plant and equipment	12,880,850	11,787,669
Current assets
Cash and cash equivalents	208,064	24,550
Accounts receivable, net	236,466	230,571
Gas stored underground	84,886	130,138
Other current assets	72,743	72,772
Total current assets	602,159	458,031
Goodwill	730,706	730,706
Deferred charges and other assets	657,267	391,213
Total assets	14,870,982	13,367,619
Shareholders’ equity
Common stock, no par value (stated at $0.005 per share); 200,000,000 shares authorized; issued and outstanding: June 30, 2020 — 123,351,267 shares; September 30, 2019 — 119,338,925 shares	617	597
Additional paid-in capital	4,100,130	3,712,194
Accumulated other comprehensive loss	(116,727)	(114,583)
Retained earnings	2,477,451	2,152,015
Shareholders’ equity	6,461,471	5,750,223
Long-term debt	4,531,341	3,529,452
Total capitalization	10,992,812	9,279,675
Current liabilities
Accounts payable and accrued liabilities	200,116	265,024
Other current liabilities	502,413	479,501
Short-term debt	0	464,915
Current maturities of long-term debt	157	0
Total current liabilities	702,686	1,209,440
Deferred income taxes	1,420,065	1,300,015
Regulatory excess deferred taxes	702,493	705,101
Regulatory cost of removal obligation	458,101	473,172
Deferred credits and other liabilities	594,825	400,216
Total shareholders' equity and liabilities	$ 14,870,982	$ 13,367,619

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2020	Sep. 30, 2019
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)	123,351,267	119,338,925
Common stock outstanding (in shares)	123,351,267	119,338,925

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating revenues	$ 492,995	$ 485,738	$ 2,346,223	$ 2,458,165
Purchased gas cost	26,072	31,326	640,823	845,167
Operation and maintenance expense	149,460	164,545	449,529	452,572
Depreciation and amortization expense	107,104	97,700	318,082	290,537
Taxes, other than income	71,324	69,965	214,535	213,546
Operating income	139,035	122,202	723,254	656,343
Other non-operating income	7,235	1,645	9,133	(1,846)
Interest charges	19,580	19,592	68,980	74,390
Income before income taxes	126,690	104,255	663,407	580,107
Income tax expense	8,899	23,789	127,297	127,107
Net income	$ 117,791	$ 80,466	$ 536,110	$ 453,000
Basic net income per share (USD per share)	$ 0.96	$ 0.68	$ 4.38	$ 3.89
Diluted net income per share (USD per share)	0.96	0.68	4.37	3.88
Cash dividends per share (USD per share)	$ 0.575	$ 0.525	$ 1.725	$ 1.575
Basic weighted average shares outstanding (in shares)	123,026	118,075	122,352	116,485
Diluted weighted average shares outstanding (in shares)	123,032	118,430	122,463	116,673
Other comprehensive income (loss), net of tax
Net unrealized holding gains on available-for-sale securities, net of tax	$ 364	$ 94	$ 200	$ 191
Cash flow hedges:
Amortization and unrealized gain (loss) on interest rate agreements, net of tax	(4,450)	1,053	(2,344)	(23,997)
Total other comprehensive income (loss)	(4,086)	1,147	(2,144)	(23,806)
Total comprehensive income	113,705	81,613	533,966	429,194
Distribution segment
Operating revenues	434,650	444,287	2,194,786	2,339,660
Pipeline and storage segment
Operating revenues	58,345	41,451	151,437	118,505
Operating Segments | Distribution segment
Operating revenues	435,308	444,944	2,196,817	2,341,668
Purchased gas cost	126,093	139,518	942,586	1,147,598
Operation and maintenance expense	107,537	123,998	337,740	347,386
Depreciation and amortization expense	77,187	70,611	229,526	210,224
Taxes, other than income	61,980	62,134	190,636	189,377
Operating income	62,511	48,683	496,329	447,083
Other non-operating income	5,167	3,005	1,930	1,791
Interest charges	7,969	10,597	35,128	44,703
Income before income taxes	59,709	41,091	463,131	404,171
Income tax expense	810	8,693	87,411	85,195
Net income	58,899	32,398	375,720	318,976
Operating Segments | Pipeline and storage segment
Operating revenues	158,008	149,198	452,421	419,318
Purchased gas cost	(11)	(96)	290	(544)
Operation and maintenance expense	42,234	40,855	112,751	106,120
Depreciation and amortization expense	29,917	27,089	88,556	80,313
Taxes, other than income	9,344	7,831	23,899	24,169
Operating income	76,524	73,519	226,925	209,260
Other non-operating income	2,068	(1,360)	7,203	(3,637)
Interest charges	11,611	8,995	33,852	29,687
Income before income taxes	66,981	63,164	200,276	175,936
Income tax expense	8,089	15,096	39,886	41,912
Net income	58,892	48,068	160,390	134,024
Intersegment eliminations
Operating revenues	(100,321)	(108,404)	(303,015)	(302,821)
Purchased gas cost	(100,010)	(108,096)	(302,053)	(301,887)
Operation and maintenance expense	(311)	(308)	(962)	(934)
Depreciation and amortization expense	0	0	0	0
Taxes, other than income	0	0	0	0
Operating income	0	0	0	0
Other non-operating income	0	0	0	0
Interest charges	0	0	0	0
Income before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Net income	0	0	0	0
Intersegment eliminations | Distribution segment
Operating revenues	658	657	2,031	2,008
Intersegment eliminations | Pipeline and storage segment
Operating revenues	99,663	107,747	300,984	300,813
Purchased gas cost
Purchased gas cost	26,072	31,326	640,823	845,167
Purchased gas cost | Operating Segments | Distribution segment
Purchased gas cost	126,093	139,518	942,586	1,147,598
Purchased gas cost | Operating Segments | Pipeline and storage segment
Purchased gas cost	(11)	(96)	290	(544)
Purchased gas cost | Intersegment eliminations
Purchased gas cost	$ (100,010)	$ (108,096)	$ (302,053)	$ (301,887)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net unrealized holding losses on available-for-sale securities, tax	$ 96	$ 27	$ 47	$ 56
Amortization and unrealized gain (loss) on interest rate agreements, tax	$ (1,115)	$ 312	$ (492)	$ (7,093)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows From Operating Activities
Net income	$ 536,110	$ 453,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	318,082	290,537
Deferred income taxes	137,996	120,220
One-time income tax benefit	(20,962)	0
Other	5,935	9,649
Net assets / liabilities from risk management activities	1,295	(1,976)
Net change in operating assets and liabilities	(82,970)	(62,502)
Net cash provided by operating activities	895,486	808,928
Cash Flows From Investing Activities
Capital expenditures	(1,405,673)	(1,199,199)
Proceeds from the sale of discontinued operations	0	4,000
Debt and equity securities activities, net	(692)	(4,041)
Other, net	6,098	3,839
Net cash used in investing activities	(1,400,267)	(1,195,401)
Cash Flows From Financing Activities
Net decrease in short-term debt	(464,915)	(500,838)
Net proceeds from equity offering	358,047	593,731
Issuance of common stock through stock purchase and employee retirement plans	14,125	14,128
Proceeds from issuance of long-term debt	999,450	1,045,221
Settlement of interest rate swaps	0	(90,141)
Repayment of long-term debt	0	(450,000)
Cash dividends paid	(210,674)	(181,982)
Debt issuance costs	(7,738)	(11,254)
Net cash provided by financing activities	688,295	418,865
Net increase in cash and cash equivalents	183,514	32,392
Cash and cash equivalents at beginning of period	24,550	13,771
Cash and cash equivalents at end of period	$ 208,064	$ 46,163

Nature of Business

Nature of Business	9 Months Ended
	Jun. 30, 2020
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, 2020 , 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, 2020
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, 2019 . 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, 2019 . Because of seasonal and other factors, the results of operations for the nine -month period ended June 30, 2020 are not indicative of our results of operations for the full 2020 fiscal year, which ends September 30, 2020 . Except as noted below related to recent ratemaking activity and in Note 12 to the unaudited condensed consolidated financial statements regarding new cash flow hedges, no events have occurred subsequent to the balance sheet date that would require recognition or disclosure in the unaudited condensed consolidated financial statements. Significant accounting policies Our accounting policies are described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . During the second quarter of fiscal 2020, we completed our annual goodwill impairment assessment. Based on the assessment performed, we determined that our goodwill was not impaired. Accounting pronouncements adopted in fiscal 2020 In February 2016, the Financial Accounting Standards Board (FASB) issued a comprehensive new leasing standard that requires lessees to recognize a lease liability and a right-of-use (ROU) asset for all leases, including operating leases on its balance sheet. The new standard was effective for us beginning on October 1, 2019. See Note 6 to the unaudited condensed consolidated financial statements for further details regarding our adoption of the new lease standard and the related disclosures. Accounting pronouncements that will be effective after fiscal 2020 In March 2020, the 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. In December 2019, the FASB issued new guidance related to accounting for income taxes which removes certain exceptions for recognizing deferred taxes for investments, performing intraperiod allocations and calculating income taxes in interim periods. The new standard also adds guidance to reduce complexity in certain areas, such as recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. The new standard will be effective for us beginning on October 1, 2021; early adoption is permitted. We are currently evaluating the potential impact of this new guidance on our financial position, results of operations and cash flows. In June 2016, the FASB issued new guidance which will require 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, entities will estimate credit losses over the entire contractual term of the instrument from the date of initial recognition of that instrument. In contrast, current U.S. GAAP is based on an incurred loss model that delays recognition of credit losses until it is probable the loss has been incurred. 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. The new standard will be effective for us beginning on October 1, 2020. We are currently evaluating the potential impact of this new guidance 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 and our regulatory excess deferred taxes and regulatory cost of removal obligation are reported separately. Significant regulatory assets and liabilities as of June 30, 2020 and September 30, 2019 included the following: June 30, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 79,108 $ 86,089 Infrastructure mechanisms (1) 180,390 131,894 Deferred gas costs — 23,766 Recoverable loss on reacquired debt 5,259 6,551 Deferred pipeline record collection costs 28,700 26,418 Rate case costs 401 1,346 Other 6,173 8,483 $ 300,031 $ 284,547 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 723,400 $ 726,307 Regulatory cost of service reserve 2,559 5,238 Regulatory cost of removal obligation 528,932 528,893 Deferred gas costs 48,917 14,112 Asset retirement obligation 17,054 17,054 APT annual adjustment mechanism 62,461 78,402 Other 21,923 16,120 $ 1,405,246 $ 1,386,126 (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) Due to the passage of the Kansas House Bill 2585, on June 1, 2020, we remeasured our deferred tax liability and updated our state deferred tax rate resulting in a $12.1 million regulatory liability as of June 30, 2020 . See further details in Note 11. The remaining amount reflects the remeasurement of the net deferred tax liability included in our rate base as a result of the Tax Cuts and Jobs Act of 2017 (the "TCJA"). Of this amount, $20.9 million as of June 30, 2020 and $21.2 million as of September 30, 2019 is recorded in other current liabilities. These liabilities are being returned to customers in most of our jurisdictions on a provisional basis over 15 to 46 years until formal orders establish the final refund periods. During the nine months ended June 30, 2020 , we received regulatory orders in Louisiana, Mississippi, Texas (including APT) and Virginia to defer into a regulatory asset all expenses, beyond the normal course of business, related to Coronavirus Disease 2019 (COVID-19 or virus), including bad debt expense. Subsequent to June 30, 2020, we also received a regulatory order in Kansas to defer into a regulatory asset these expenses. As of June 30, 2020 , no amounts have been recorded as regulatory assets or liabilities for expenses related to COVID-19, including bad debt expense.

Segment Information

Segment Information	9 Months Ended
	Jun. 30, 2020
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, 2019 . Income statements and capital expenditures for the three and nine months ended June 30, 2020 and 2019 by segment are presented in the following tables: 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 Three Months Ended June 30, 2019 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 444,287 $ 41,451 $ — $ 485,738 Intersegment revenues 657 107,747 (108,404 ) — Total operating revenues 444,944 149,198 (108,404 ) 485,738 Purchased gas cost 139,518 (96 ) (108,096 ) 31,326 Operation and maintenance expense 123,998 40,855 (308 ) 164,545 Depreciation and amortization expense 70,611 27,089 — 97,700 Taxes, other than income 62,134 7,831 — 69,965 Operating income 48,683 73,519 — 122,202 Other non-operating income (expense) 3,005 (1,360 ) — 1,645 Interest charges 10,597 8,995 — 19,592 Income before income taxes 41,091 63,164 — 104,255 Income tax expense 8,693 15,096 — 23,789 Net income $ 32,398 $ 48,068 $ — $ 80,466 Capital expenditures $ 316,825 $ 104,788 $ — $ 421,613 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 Nine Months Ended June 30, 2019 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,339,660 $ 118,505 $ — $ 2,458,165 Intersegment revenues 2,008 300,813 (302,821 ) — Total operating revenues 2,341,668 419,318 (302,821 ) 2,458,165 Purchased gas cost 1,147,598 (544 ) (301,887 ) 845,167 Operation and maintenance expense 347,386 106,120 (934 ) 452,572 Depreciation and amortization expense 210,224 80,313 — 290,537 Taxes, other than income 189,377 24,169 — 213,546 Operating income 447,083 209,260 — 656,343 Other non-operating income (expense) 1,791 (3,637 ) — (1,846 ) Interest charges 44,703 29,687 — 74,390 Income before income taxes 404,171 175,936 — 580,107 Income tax expense 85,195 41,912 — 127,107 Net income $ 318,976 $ 134,024 $ — $ 453,000 Capital expenditures $ 912,640 $ 286,559 $ — $ 1,199,199 Balance sheet information at June 30, 2020 and September 30, 2019 by segment is presented in the following tables: June 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 9,644,503 $ 3,236,347 $ — $ 12,880,850 Total assets $ 14,098,715 $ 3,471,282 $ (2,699,015 ) $ 14,870,982 September 30, 2019 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 8,737,590 $ 3,050,079 $ — $ 11,787,669 Total assets $ 12,579,741 $ 3,279,323 $ (2,491,445 ) $ 13,367,619

Earnings Per Share

Earnings Per Share	9 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock. Additionally, the weighted average shares outstanding for diluted EPS includes the incremental effects of the forward sale agreements, discussed in Note 8 to the 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, 2020 and 2019 are calculated as follows: Three Months Ended June 30 Nine Months Ended June 30 2020 2019 2020 2019 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 117,791 $ 80,466 $ 536,110 $ 453,000 Less: Income allocated to participating securities 88 64 408 386 Income available to common shareholders $ 117,703 $ 80,402 $ 535,702 $ 452,614 Basic weighted average shares outstanding 123,026 118,075 122,352 116,485 Net income per share — Basic $ 0.96 $ 0.68 $ 4.38 $ 3.89 Diluted Earnings Per Share Income available to common shareholders $ 117,703 $ 80,402 $ 535,702 $ 452,614 Effect of dilutive shares — — — — Income available to common shareholders $ 117,703 $ 80,402 $ 535,702 $ 452,614 Basic weighted average shares outstanding 123,026 118,075 122,352 116,485 Dilutive shares 6 355 111 188 Diluted weighted average shares outstanding 123,032 118,430 122,463 116,673 Net income per share - Diluted $ 0.96 $ 0.68 $ 4.37 $ 3.88

Revenue

Revenue	9 Months Ended
	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Our revenue recognition policy is fully described in Note 2 to the financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . 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, 2020 and 2019 . Three Months Ended June 30, 2020 Three Months Ended June 30, 2019 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 286,937 $ — $ 269,484 $ — Commercial 101,055 — 113,591 — Industrial 17,019 — 25,277 — Public authority and other 7,063 — 6,305 — Total gas sales revenues 412,074 — 414,657 — Transportation revenues 22,532 164,675 22,923 166,864 Miscellaneous revenues 2,793 2,277 6,125 2,407 Revenues from contracts with customers 437,399 166,952 443,705 169,271 Alternative revenue program revenues (1) (2,567 ) (8,944 ) 748 (20,073 ) Other revenues 476 — 491 — Total operating revenues $ 435,308 $ 158,008 $ 444,944 $ 149,198 Nine Months Ended June 30, 2020 Nine Months Ended June 30, 2019 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 1,435,328 $ — $ 1,513,239 $ — Commercial 543,148 — 611,474 — Industrial 67,572 — 95,701 — Public authority and other 34,747 — 36,677 — Total gas sales revenues 2,080,795 — 2,257,091 — Transportation revenues 77,676 471,433 76,005 456,558 Miscellaneous revenues 16,565 8,767 20,439 6,862 Revenues from contracts with customers 2,175,036 480,200 2,353,535 463,420 Alternative revenue program revenues (1) 20,320 (27,779 ) (13,388 ) (44,102 ) Other revenues 1,461 — 1,521 — Total operating revenues $ 2,196,817 $ 452,421 $ 2,341,668 $ 419,318 (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 revenue benchmark.

Leases

Leases	9 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Leases	Leases We adopted the provisions of the new lease accounting standard beginning on October 1, 2019, using the optional transition method, which allowed us to apply the provisions of the new standard to all leases that existed as of the date of adoption. Therefore, results for reporting periods beginning on October 1, 2019 are presented under the new lease accounting standard and prior periods are presented under the former lease accounting standard. The new guidance included several practical expedients to facilitate the implementation of the new standard. The following summarizes the practical expedients we used to implement the standard. • We elected to bundle our lease and non-lease components as a single component for all asset classes. • We elected not to perform the following: ◦ Evaluate existing or expired land easements prior to October 1, 2019 to determine if they are leases. ◦ Include short-term leases in the calculation of our lease liability. ◦ Evaluate existing or expired contracts to determine if they are leases. ◦ Assess lease classification for existing or expired leases. ◦ Review initial direct costs for existing leases. ◦ Use hindsight in order to determine the lease term or impairment of our ROU assets. Upon adoption of this new guidance, we recorded ROU assets and lease liabilities of $231.3 million . Additionally, we reclassified a net $6.5 million of accrued and prepaid lease costs to the ROU asset and $2.5 million related to an existing finance lease from deferred credits and other liabilities to long-term debt. Implementation of the new lease accounting guidance had no material impact on our condensed consolidated statements of comprehensive income or our condensed consolidated statements of cash flows. Additionally, we did not record a cumulative-effect adjustment to retained earnings on the opening balance sheet. New Lease Accounting Policy We determine if an arrangement is a lease at the inception of the agreement based on the terms and conditions in the contract. A contract contains a lease if there is an identified asset and we have the right to control the asset. We are the lessee for substantially all of our leasing activity, which primarily includes operating leases for office and warehouse space, tower space, vehicles and heavy equipment used in our operations. We are also a lessee in finance leases for service centers. We record a lease liability and a corresponding ROU asset for all of our leases with a term greater than 12 months. For lease contracts containing renewal and termination options, we include the option period in the lease term when it is reasonably certain the option will be exercised. We most frequently assume renewal options at the inception of the arrangement for our tower and fleet leases, based on our anticipated use of the assets. Real estate leases that contain a renewal option are evaluated on a lease-by-lease basis to determine if the option period should be included in the lease term. Currently, we have not included material renewal options for real estate leases in our ROU asset or lease liability. The following table presents our weighted average remaining lease term for our leases. June 30, 2020 Weighted average remaining lease term (years) Finance leases 19.36 Operating leases 10.69 The lease liability represents the present value of all lease payments over the lease term. The discount rate used to determine the present value of the lease liability is the rate implicit in the lease unless that rate cannot be readily determined. We use the implicit rate stated in the agreement to determine the lease liability for our fleet leases. We use our corporate collateralized incremental borrowing rate as the discount rate for all other lease agreements. This rate is appropriate because we believe it represents the rate we would have incurred to borrow funds to acquire the leased asset over a similar term. We calculated this rate using a combination of inputs, including our current credit rating, quoted market prices of interest rates for our publicly traded unsecured debt, observable market yield curve data for peer companies with a credit rating one notch higher than our current credit rating and the lease term. The following table represents our weighted average discount rate: June 30, 2020 Weighted average discount rate Finance leases 8.02 % Operating leases 2.91 % The ROU asset represents the right to use the underlying asset for the lease term, and is equal to the lease liability, adjusted for prepaid or accrued lease payments and any lease incentives that have been paid to us or when we are reasonably certain to incur costs equal to or greater than the allowance defined in the contract. Variable payments included in our leasing arrangements are expensed in the period in which the obligation for these payments is incurred. Variable payments are dependent on usage, output or may vary for other reasons. Most of our variable lease expense is related to tower leases that have escalating payments based on changes to a stated CPI index, and usage of certain office equipment. We have not provided material residual value guarantees for our leases, nor do our leases contain material restrictions or covenants. Lease costs for the three and nine months ended June 30, 2020 are presented in the table below. These costs include both amounts recognized in expense and amounts capitalized. For the three and nine months ended June 30, 2020 , we did not have material short-term lease costs or variable lease costs. Three Months Ended June 30, 2020 Nine Months Ended June 30, 2020 (In thousands) Finance lease cost $ 197 $ 376 Operating lease cost 10,371 30,461 Total lease cost $ 10,568 $ 30,837 Our ROU assets and lease liabilities are presented as follows on the condensed consolidated balance sheets (unaudited): Balance Sheet Classification June 30, 2020 (In thousands) Assets Finance leases Net Property, Plant and Equipment $ 8,554 Operating leases Deferred charges and other assets 225,311 Total right-of-use assets $ 233,865 Liabilities Current Finance leases Current maturities of long-term debt $ 157 Operating leases Other current liabilities 33,884 Noncurrent Finance leases Long-term debt 8,479 Operating leases Deferred credits and other liabilities 200,390 Total lease liabilities $ 242,910 Other pertinent information related to leases was as follows. During the nine months ended June 30, 2020 , amounts paid in cash for our finance leases were not material. Nine Months Ended June 30, 2020 (In thousands) Cash paid amounts included in the measurement of lease liabilities Operating cash flows used for operating leases $ 28,011 Right-of-use assets obtained in exchange for lease obligations Finance leases $ 6,143 Operating leases $ 23,628 Maturities of our lease liabilities as of June 30, 2020 , presented on a rolling 12-month basis, were as follows: Total Finance Leases Operating Leases (In thousands) Year 1 $ 39,017 $ 738 $ 38,279 Year 2 37,983 749 37,234 Year 3 33,112 759 32,353 Year 4 26,386 770 25,616 Year 5 17,607 781 16,826 Thereafter 139,172 12,862 126,310 Total lease payments 293,277 16,659 276,618 Less: Imputed interest 50,367 8,023 42,344 Total $ 242,910 $ 8,636 $ 234,274 Reported as of June 30, 2020 Short-term lease liabilities $ 34,041 $ 157 $ 33,884 Long-term lease liabilities 208,869 8,479 200,390 Total lease liabilities $ 242,910 $ 8,636 $ 234,274 Disclosures Related to Prior Periods The future minimum lease payments as of September 30, 2019 were as follows: Operating Leases (1) Capital Lease (In thousands) 2020 $ 21,017 $ 243 2021 20,416 248 2022 19,370 253 2023 18,071 258 2024 15,718 263 Thereafter 105,544 4,343 Total minimum lease payments $ 200,136 5,608 Less amount representing interest 3,018 Present value of net minimum lease payments $ 2,590 (1) Future minimum lease payments do not include amounts for fleet leases and other de minimis items that can be renewed beyond the initial lease term. The Company anticipates renewing the leases beyond the initial term, but the anticipated payments associated with the renewals do not meet the definition of expected minimum lease payments and therefore are not included above. Expected payments are $17.6 million in 2020, $18.0 million in 2021, $11.8 million in 2022, $8.5 million in 2023, $5.4 million 2024 and $2.7 million thereafter. Consolidated lease and rental expense for the three and nine months ended June 30, 2019 was $10.5 million and $30.7 million
Leases	Leases We adopted the provisions of the new lease accounting standard beginning on October 1, 2019, using the optional transition method, which allowed us to apply the provisions of the new standard to all leases that existed as of the date of adoption. Therefore, results for reporting periods beginning on October 1, 2019 are presented under the new lease accounting standard and prior periods are presented under the former lease accounting standard. The new guidance included several practical expedients to facilitate the implementation of the new standard. The following summarizes the practical expedients we used to implement the standard. • We elected to bundle our lease and non-lease components as a single component for all asset classes. • We elected not to perform the following: ◦ Evaluate existing or expired land easements prior to October 1, 2019 to determine if they are leases. ◦ Include short-term leases in the calculation of our lease liability. ◦ Evaluate existing or expired contracts to determine if they are leases. ◦ Assess lease classification for existing or expired leases. ◦ Review initial direct costs for existing leases. ◦ Use hindsight in order to determine the lease term or impairment of our ROU assets. Upon adoption of this new guidance, we recorded ROU assets and lease liabilities of $231.3 million . Additionally, we reclassified a net $6.5 million of accrued and prepaid lease costs to the ROU asset and $2.5 million related to an existing finance lease from deferred credits and other liabilities to long-term debt. Implementation of the new lease accounting guidance had no material impact on our condensed consolidated statements of comprehensive income or our condensed consolidated statements of cash flows. Additionally, we did not record a cumulative-effect adjustment to retained earnings on the opening balance sheet. New Lease Accounting Policy We determine if an arrangement is a lease at the inception of the agreement based on the terms and conditions in the contract. A contract contains a lease if there is an identified asset and we have the right to control the asset. We are the lessee for substantially all of our leasing activity, which primarily includes operating leases for office and warehouse space, tower space, vehicles and heavy equipment used in our operations. We are also a lessee in finance leases for service centers. We record a lease liability and a corresponding ROU asset for all of our leases with a term greater than 12 months. For lease contracts containing renewal and termination options, we include the option period in the lease term when it is reasonably certain the option will be exercised. We most frequently assume renewal options at the inception of the arrangement for our tower and fleet leases, based on our anticipated use of the assets. Real estate leases that contain a renewal option are evaluated on a lease-by-lease basis to determine if the option period should be included in the lease term. Currently, we have not included material renewal options for real estate leases in our ROU asset or lease liability. The following table presents our weighted average remaining lease term for our leases. June 30, 2020 Weighted average remaining lease term (years) Finance leases 19.36 Operating leases 10.69 The lease liability represents the present value of all lease payments over the lease term. The discount rate used to determine the present value of the lease liability is the rate implicit in the lease unless that rate cannot be readily determined. We use the implicit rate stated in the agreement to determine the lease liability for our fleet leases. We use our corporate collateralized incremental borrowing rate as the discount rate for all other lease agreements. This rate is appropriate because we believe it represents the rate we would have incurred to borrow funds to acquire the leased asset over a similar term. We calculated this rate using a combination of inputs, including our current credit rating, quoted market prices of interest rates for our publicly traded unsecured debt, observable market yield curve data for peer companies with a credit rating one notch higher than our current credit rating and the lease term. The following table represents our weighted average discount rate: June 30, 2020 Weighted average discount rate Finance leases 8.02 % Operating leases 2.91 % The ROU asset represents the right to use the underlying asset for the lease term, and is equal to the lease liability, adjusted for prepaid or accrued lease payments and any lease incentives that have been paid to us or when we are reasonably certain to incur costs equal to or greater than the allowance defined in the contract. Variable payments included in our leasing arrangements are expensed in the period in which the obligation for these payments is incurred. Variable payments are dependent on usage, output or may vary for other reasons. Most of our variable lease expense is related to tower leases that have escalating payments based on changes to a stated CPI index, and usage of certain office equipment. We have not provided material residual value guarantees for our leases, nor do our leases contain material restrictions or covenants. Lease costs for the three and nine months ended June 30, 2020 are presented in the table below. These costs include both amounts recognized in expense and amounts capitalized. For the three and nine months ended June 30, 2020 , we did not have material short-term lease costs or variable lease costs. Three Months Ended June 30, 2020 Nine Months Ended June 30, 2020 (In thousands) Finance lease cost $ 197 $ 376 Operating lease cost 10,371 30,461 Total lease cost $ 10,568 $ 30,837 Our ROU assets and lease liabilities are presented as follows on the condensed consolidated balance sheets (unaudited): Balance Sheet Classification June 30, 2020 (In thousands) Assets Finance leases Net Property, Plant and Equipment $ 8,554 Operating leases Deferred charges and other assets 225,311 Total right-of-use assets $ 233,865 Liabilities Current Finance leases Current maturities of long-term debt $ 157 Operating leases Other current liabilities 33,884 Noncurrent Finance leases Long-term debt 8,479 Operating leases Deferred credits and other liabilities 200,390 Total lease liabilities $ 242,910 Other pertinent information related to leases was as follows. During the nine months ended June 30, 2020 , amounts paid in cash for our finance leases were not material. Nine Months Ended June 30, 2020 (In thousands) Cash paid amounts included in the measurement of lease liabilities Operating cash flows used for operating leases $ 28,011 Right-of-use assets obtained in exchange for lease obligations Finance leases $ 6,143 Operating leases $ 23,628 Maturities of our lease liabilities as of June 30, 2020 , presented on a rolling 12-month basis, were as follows: Total Finance Leases Operating Leases (In thousands) Year 1 $ 39,017 $ 738 $ 38,279 Year 2 37,983 749 37,234 Year 3 33,112 759 32,353 Year 4 26,386 770 25,616 Year 5 17,607 781 16,826 Thereafter 139,172 12,862 126,310 Total lease payments 293,277 16,659 276,618 Less: Imputed interest 50,367 8,023 42,344 Total $ 242,910 $ 8,636 $ 234,274 Reported as of June 30, 2020 Short-term lease liabilities $ 34,041 $ 157 $ 33,884 Long-term lease liabilities 208,869 8,479 200,390 Total lease liabilities $ 242,910 $ 8,636 $ 234,274 Disclosures Related to Prior Periods The future minimum lease payments as of September 30, 2019 were as follows: Operating Leases (1) Capital Lease (In thousands) 2020 $ 21,017 $ 243 2021 20,416 248 2022 19,370 253 2023 18,071 258 2024 15,718 263 Thereafter 105,544 4,343 Total minimum lease payments $ 200,136 5,608 Less amount representing interest 3,018 Present value of net minimum lease payments $ 2,590 (1) Future minimum lease payments do not include amounts for fleet leases and other de minimis items that can be renewed beyond the initial lease term. The Company anticipates renewing the leases beyond the initial term, but the anticipated payments associated with the renewals do not meet the definition of expected minimum lease payments and therefore are not included above. Expected payments are $17.6 million in 2020, $18.0 million in 2021, $11.8 million in 2022, $8.5 million in 2023, $5.4 million 2024 and $2.7 million thereafter. Consolidated lease and rental expense for the three and nine months ended June 30, 2019 was $10.5 million and $30.7 million

Debt

Debt	9 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Debt	Debt The nature and terms of our debt instruments and credit facilities are described in detail in Note 6 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . Other than as described below, there were no material changes in the terms of our debt instruments during the nine months ended June 30, 2020 . Long-term debt at June 30, 2020 and September 30, 2019 consisted of the following: June 30, 2020 September 30, 2019 (In thousands) Unsecured 3.00% Senior Notes, due 2027 $ 500,000 $ 500,000 Unsecured 2.625% Senior Notes, due 2029 300,000 — 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 — Floating-rate term loan, due 2022 200,000 — 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 (see Note 6) 8,636 — Total long-term debt 4,568,636 3,560,000 Less: Original issue (premium) / discount on unsecured senior notes and debentures 623 193 Debt issuance cost 36,515 30,355 Current maturities 157 — $ 4,531,341 $ 3,529,452 On April 9, 2020, we entered into a two year, $200 million term loan agreement that bears interest at a rate of LIBOR plus 1.25 percent. The term loan was used to pay down borrowings pursuant to our commercial paper program. On October 2, 2019, we completed a public offering of $300 million of 2.625% senior notes due 2029 and $500 million of 3.375% senior notes due 2049. We received net proceeds from the offering, after the underwriting discount and offering expenses, of $791.7 million , that were used for general corporate purposes, including the repayment of borrowings pursuant to our commercial paper program. The effective interest rate on these notes is 2.72% and 3.42% , after giving effect to the offering costs. 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. Changes in the price of natural gas and the amount of natural gas we need to supply our customers’ needs could significantly affect our borrowing requirements. Our short-term borrowings typically reach their highest levels in the winter months. As of June 30, 2020, our short-term borrowing requirements were satisfied through a combination of a $1.5 billion commercial paper program and four committed revolving credit facilities with third-party lenders that provide approximately $2.2 billion of total working capital funding. The primary source of our funding is our commercial paper program, which is supported by a five-year unsecured $1.5 billion credit facility that expires on September 25, 2023. The 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 1.25 percent , 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, 2020 , there were no amounts outstanding under our commercial paper program. At September 30, 2019 , a total of $464.9 million was outstanding. Additionally, we had a $25 million 364 -day unsecured facility that was renewed effective April 1, 2020 and increased to $50 million , which is used to provide working capital funding. There were no borrowings outstanding under this facility as of June 30, 2020 . Finally, we had a $10 million 364 -day unsecured revolving credit facility, which was replaced on April 30, 2020, with a new $50 million 364 -day unsecured revolving credit facility, which is used primarily to issue letters of credit. At June 30, 2020 , there were no borrowings outstanding under the new facility; however, outstanding letters of credit reduced the total amount available to us under our $50 million facility to $44.4 million . On April 23, 2020, we executed a new $600 million 364 -day unsecured revolving credit facility to provide additional working capital funding. The 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 1.25 percent , based on the Company's credit ratings. At June 30, 2020 , there were no borrowings outstanding under this facility. 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, 2020 , our total-debt-to-total-capitalization ratio, as defined in the agreements, was 43 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, 2020 . 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, 2020
Equity [Abstract]
Shareholders' Equity	Shareholders' Equity The following tables present a reconciliation of changes in stockholders' equity for the three and nine months ended June 30, 2020 and 2019 . 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 Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2018 111,273,683 $ 556 $ 2,974,926 $ (83,647 ) $ 1,878,116 $ 4,769,951 Net income — — — — 157,646 157,646 Other comprehensive loss — — — (22,258 ) — (22,258 ) Cash dividends ($0.525 per share) — — — — (58,722 ) (58,722 ) Cumulative effect of accounting change — — — (8,210 ) 8,210 — Common stock issued: Public and other stock offerings 5,434,812 27 498,948 — — 498,975 Stock-based compensation plans 184,464 1 2,602 — — 2,603 Balance, December 31, 2018 116,892,959 584 3,476,476 (114,115 ) 1,985,250 5,348,195 Net income — — — — 214,888 214,888 Other comprehensive loss — — — (2,695 ) — (2,695 ) Cash dividends ($0.525 per share) — — — — (61,606 ) (61,606 ) Common stock issued: Public and other stock offerings 61,006 1 5,453 — — 5,454 Stock-based compensation plans 28,938 — 3,865 — — 3,865 Balance, March 31, 2019 116,982,903 585 3,485,794 (116,810 ) 2,138,532 5,508,101 Net income — — — — 80,466 80,466 Other comprehensive income — — — 1,147 — 1,147 Cash dividends ($0.525 per share) — — — — (61,654 ) (61,654 ) Common stock issued: Public and other stock offerings 1,127,244 5 103,425 — — 103,430 Stock-based compensation plans 85,966 1 10,505 — — 10,506 Balance, June 30, 2019 118,196,113 $ 591 $ 3,599,724 $ (115,663 ) $ 2,157,344 $ 5,641,996 Shelf Registration, At-the-Market Equity Sales Program and Equity Issuances On February 11, 2020, we filed a shelf registration statement with the Securities and Exchange Commission (SEC) that allows us to issue up to $4.0 billion in common stock and/or debt securities, which expires February 11, 2023. This shelf registration statement replaced our previous shelf registration statement which was filed on November 13, 2018 (2018 Registration Statement). At June 30, 2020 , approximately $3.0 billion of securities remained available for issuance under the shelf registration statement. On February 12, 2020, we filed a prospectus supplement under the shelf registration statement relating to an at-the-market (ATM) equity sales program (February 2020 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 November 19, 2018 (November 2018 ATM), which was exhausted during the second quarter of fiscal 2020 with the execution of forward sales. During the nine months ended June 30, 2020 , we executed forward sales under the February 2020 ATM and the November 2018 ATM equity sales programs with various forward sellers who borrowed and sold 4,148,057 shares of our common stock at an aggregate price of $453.9 million . Additionally, during the nine months ended June 30, 2020 , we settled forward sale agreements with respect to 3,146,108 shares that had been borrowed and sold by various forward sellers during fiscal 2019 under the November 2018 ATM for net proceeds of $314.6 million . As of June 30, 2020 , the February 2020 ATM program had approximately $621 million of equity available for issuance. On November 30, 2018, we filed a prospectus supplement under the 2018 Registration Statement relating to an underwriting agreement to sell 5,390,836 shares of our common stock for $500 million . After expenses, net proceeds from the offering were $494.1 million . Concurrently, we entered into separate forward sales agreements with two forward sellers who borrowed and sold 2,668,464 shares of our common stock at an aggregate price of $247.5 million . During the nine months ended June 30, 2019, we settled forward sale agreements with respect to 1,089,700 of the shares that had been borrowed and sold for net proceeds of $99.6 million . During the nine months ended June 30, 2020 , we settled the remaining 485,189 shares under these forward sale agreements for net proceeds of $44.4 million . During the nine months ended June 30, 2019, we executed forward sales under the November 2018 ATM with various forward sellers who borrowed and sold 2,721,072 shares of our common stock at an aggregate price of $268.7 million . If we had settled all shares that remain available under our outstanding forward sale agreements as of June 30, 2020 , we would have received proceeds of $547.2 million , based on a net price of $106.33 per share. Additional details are presented below. Maturity Shares Available Net Proceeds Available Forward Price September 30, 2020 1,662,270 $ 174,142 $ 104.76 March 31, 2021 2,089,927 229,650 $ 109.88 June 30, 2021 1,394,423 143,430 $ 102.86 Total 5,146,620 $ 547,222 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- for-Sale Securities Interest Rate Agreement Cash Flow Hedges 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 ) Available- for-Sale Securities Interest Rate Agreement Cash Flow Hedges Total (In thousands) September 30, 2018 $ 8,124 $ (91,771 ) $ (83,647 ) Other comprehensive income (loss) before reclassifications 192 (25,966 ) (25,774 ) Amounts reclassified from accumulated other comprehensive income (1 ) 1,969 1,968 Net current-period other comprehensive income (loss) 191 (23,997 ) (23,806 ) Cumulative effect of accounting change (8,210 ) — (8,210 ) June 30, 2019 $ 105 $ (115,768 ) $ (115,663 )

Interim Pension and Other Postr

Interim Pension and Other Postretirement Benefit Plan Information	9 Months Ended
	Jun. 30, 2020
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, 2020 and 2019 are presented in the following tables. Most of these costs are recoverable through our tariff rates. A portion of these costs is capitalized into our rate base or deferred as a regulatory asset or liability. The remaining costs are recorded as a component of operation and maintenance expense or other non-operating expense. Three Months Ended June 30 Pension Benefits Other Benefits 2020 2019 2020 2019 (In thousands) Components of net periodic pension cost: Service cost $ 4,652 $ 4,044 $ 3,366 $ 2,702 Interest cost (1) 5,843 6,799 2,653 2,960 Expected return on assets (1) (7,079 ) (7,113 ) (2,625 ) (2,664 ) Amortization of prior service cost (credit) (1) (58 ) (57 ) 43 43 Amortization of actuarial (gain) loss (1) 3,242 1,606 (334 ) (2,045 ) Net periodic pension cost $ 6,600 $ 5,279 $ 3,103 $ 996 Nine Months Ended June 30 Pension Benefits Other Benefits 2020 2019 2020 2019 (In thousands) Components of net periodic pension cost: Service cost $ 13,957 $ 12,134 $ 10,099 $ 8,107 Interest cost (1) 17,529 20,399 7,959 8,879 Expected return on assets (1) (21,237 ) (21,339 ) (7,874 ) (7,994 ) Amortization of prior service cost (credit) (1) (174 ) (173 ) 130 130 Amortization of actuarial (gain) loss (1) 9,725 4,821 (1,003 ) (6,134 ) Net periodic pension cost $ 19,800 $ 15,842 $ 9,311 $ 2,988 (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 financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . The amount of funding required for our defined benefit plan is determined in accordance with the Pension Protection Act of 2006 (PPA) and is influenced by the funded position of the plan when the funding requirements are determined on January 1 of each year. Based upon the determination as of January 1, 2020, we are not required to make a minimum contribution to our defined benefit plan during fiscal 2020. However, we may consider whether a voluntary contribution is prudent to maintain certain funding levels. For the nine months ended June 30, 2020 we contributed $12.2 million to our postretirement medical plans. We anticipate contributing a total of between $10 million and $20 million to our postretirement plans during fiscal 2020 .

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Jun. 30, 2020
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) is investigating an incident that occurred at a Dallas, Texas residence on February 23, 2018 that resulted in one fatality and injuries to four other residents. Together with the Railroad Commission of Texas (RRC) and the Pipeline and Hazardous Materials Safety Administration, Atmos Energy is a party to the investigation and in that capacity is working closely with the NTSB to help determine the cause of this 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, 2019 . At June 30, 2020 , we were committed to purchase 59.3 Bcf within one year, 71.5 Bcf within two to three years and 0.2 Bcf beyond three years under indexed contracts. Rate Regulatory Proceedings As of June 30, 2020 , routine rate regulatory proceedings were in progress in some 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, 2020 .

Income Taxes (Notes)

Income Taxes (Notes)	9 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On June 1, 2020, the Kansas legislature passed House Bill 2585 which eliminated the assessment of state income taxes on regulated utilities. This legislation will become effective for the Company on October 1, 2020. Due to the change in the Kansas state tax law, we completed a study of the calculations used to estimate the rate at which state deferred taxes will reverse in the future. As a result, we reduced our deferred tax liability by $32.5 million during the fiscal third quarter. We established a $12.1 million regulatory liability for excess deferred taxes that will be returned to Kansas customers. We are currently working with the Kansas Corporation Commission to determine the amortization period for this liability. We recognized $21.0 million as a one-time income tax benefit in our condensed consolidated statement of comprehensive income for the three and nine months ended June 30, 2020 . On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was signed into law. The CARES Act, among other things, includes provisions relating to refundable payroll tax credits, deferment of employer side social security payments, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The CARES Act did not have an impact on our condensed consolidated financial statements for the three and nine months ended June 30, 2020 .

Financial Instruments

Financial Instruments	9 Months Ended
	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial Instruments We currently use financial instruments to mitigate commodity price risk and to mitigate 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, 2019 . During the nine months ended June 30, 2020 , 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 2019 - 2020 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 49 percent , or 19.9 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 July 2020, we entered into forward starting interest rate swaps to effectively fix the Treasury yield component associated with $300 million of a planned issuance of unsecured senior notes in fiscal 2023 at 1.36% and $300 million of a planned issuance of unsecured senior notes in fiscal 2025 at 1.35% , which we designated as cash flow hedges at the time the agreements were executed. Accordingly, unrealized gains and losses associated with the forward starting interest rate swaps will be recorded as a component of accumulated other comprehensive income (loss). When the forward starting interest rate swaps settle, the realized gain or loss will be recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest charges over the life of the related financing arrangement. Hedge ineffectiveness to the extent incurred, will be reported as a component of interest charges. As of June 30, 2020, we had forward starting interest rate swaps to effectively fix the Treasury yield component associated with $500 million of a planned issuance of unsecured senior notes in fiscal 2021 at 0.69% and $450 million of a planned issuance of unsecured senior notes in fiscal 2022 at 1.33% , which we designated as cash flow hedges at the time the agreements were executed. As of June 30, 2020 , we had $112.1 million of net realized losses in AOCI associated with the settlement of financial instruments used to fix the Treasury yield component of the interest cost of financing various issuances of long-term debt and senior notes, which will be recognized as a component of interest charges over the life of the associated notes from the date of settlement. The remaining amortization periods for these settled amounts extend through fiscal 2049. 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, 2020 , 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, 2020 , we had 10,050 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, 2020 and September 30, 2019 . 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, 2020 and September 30, 2019 , no gross amounts and no cash collateral were netted within our consolidated balance sheet. Balance Sheet Location Assets Liabilities (In thousands) June 30, 2020 Designated As Hedges: Interest rate swaps Other current assets / Other current liabilities $ 66 $ (5,305 ) Interest rate swaps Deferred charges and other assets / Deferred credits and other liabilities 4,181 (5,300 ) Total 4,247 (10,605 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 1,370 (461 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 247 (37 ) Total 1,617 (498 ) Gross / Net Financial Instruments $ 5,864 $ (11,103 ) Balance Sheet Location Assets Liabilities (In thousands) September 30, 2019 Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ 1,586 $ (4,552 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 225 (1,249 ) Total 1,811 (5,801 ) Gross / Net Financial Instruments $ 1,811 $ (5,801 ) 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, 2020 and 2019 was $1.4 million and $1.4 million and for the nine months ended June 30, 2020 and 2019 was $4.1 million and $2.6 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, 2020 and 2019 . 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 2020 2019 2020 2019 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (4,932 ) $ — $ (4,932 ) $ (25,966 ) Recognition of losses in earnings due to settlements: Interest rate agreements 482 1,053 2,588 1,969 Total other comprehensive income (loss) from hedging, net of tax $ (4,450 ) $ 1,053 $ (2,344 ) $ (23,997 ) 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. The following amounts, net of deferred taxes, represent the expected recognition in earnings, as of June 30, 2020 , of the deferred losses recorded in AOCI associated with our financial instruments, based upon the fair values of these financial instruments at the date of settlement. However, the table below does not include the expected recognition in earnings of our outstanding interest rate swaps as those instruments have not yet settled. Interest Rate Agreements (In thousands) Next twelve months $ (4,234 ) Thereafter (107,893 ) Total $ (112,127 ) 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, 2020
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 financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . During the nine months ended June 30, 2020 , 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 8 to the financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . 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, 2020 and September 30, 2019 . Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral June 30, 2020 (In thousands) Assets: Financial instruments $ — $ 5,864 $ — $ — $ 5,864 Debt and equity securities Registered investment companies 37,229 — — — 37,229 Bond mutual funds 28,954 — — — 28,954 Bonds (2) — 34,408 — — 34,408 Money market funds — 5,126 — — 5,126 Total debt and equity securities 66,183 39,534 — — 105,717 Total assets $ 66,183 $ 45,398 $ — $ — $ 111,581 Liabilities: Financial instruments $ — $ 11,103 $ — $ — $ 11,103 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral September 30, 2019 (In thousands) Assets: Financial instruments $ — $ 1,811 $ — $ — $ 1,811 Debt and equity securities Registered investment companies 41,406 — — — 41,406 Bond mutual funds 25,966 — — — 25,966 Bonds (2) — 31,915 — — 31,915 Money market funds — 2,596 — — 2,596 Total debt and equity securities 67,372 34,511 — — 101,883 Total assets $ 67,372 $ 36,322 $ — $ — $ 103,694 Liabilities: Financial instruments $ — $ 5,801 $ — $ — $ 5,801 (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. We regularly 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 and current returns. If a determination is made that a decline in fair value is other than temporary, the related investment is written down to its estimated fair value and the other-than-temporary impairment is recognized in the statement of comprehensive income. At June 30, 2020 and September 30, 2019 , the amortized cost of our available-for-sale debt securities was $34.0 million and $31.7 million . At June 30, 2020 , we maintained investments in bonds that have contractual maturity dates ranging from July 2020 through May 2023. 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, 2020 and September 30, 2019 : June 30, 2020 September 30, 2019 (In thousands) Carrying Amount $ 4,560,000 $ 3,560,000 Fair Value $ 5,563,300 $ 4,216,249

Concentration of Credit Risk

Concentration of Credit Risk	9 Months Ended
	Jun. 30, 2020
Risks and Uncertainties [Abstract]
Concentration of Credit Risk	Concentration of Credit Risk Information regarding our concentration of credit risk is disclosed in Note 17 to the financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . During the nine months ended June 30, 2020 , there were no material changes in our concentration of credit risk.

Unaudited Financial Informati_2

Unaudited Financial Information (Policies)	9 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Accounting pronouncements adopted and not yet adopted	Accounting pronouncements adopted in fiscal 2020 In February 2016, the Financial Accounting Standards Board (FASB) issued a comprehensive new leasing standard that requires lessees to recognize a lease liability and a right-of-use (ROU) asset for all leases, including operating leases on its balance sheet. The new standard was effective for us beginning on October 1, 2019. See Note 6 to the unaudited condensed consolidated financial statements for further details regarding our adoption of the new lease standard and the related disclosures. Accounting pronouncements that will be effective after fiscal 2020 In March 2020, the 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. In December 2019, the FASB issued new guidance related to accounting for income taxes which removes certain exceptions for recognizing deferred taxes for investments, performing intraperiod allocations and calculating income taxes in interim periods. The new standard also adds guidance to reduce complexity in certain areas, such as recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. The new standard will be effective for us beginning on October 1, 2021; early adoption is permitted. We are currently evaluating the potential impact of this new guidance on our financial position, results of operations and cash flows. In June 2016, the FASB issued new guidance which will require 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, entities will estimate credit losses over the entire contractual term of the instrument from the date of initial recognition of that instrument. In contrast, current U.S. GAAP is based on an incurred loss model that delays recognition of credit losses until it is probable the loss has been incurred. 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. The new standard will be effective for us beginning on October 1, 2020. We are currently evaluating the potential impact of this new guidance on our financial position, results of operations and cash flows.
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 and our regulatory excess deferred taxes and regulatory cost of removal obligation are reported separately.
Leases	New Lease Accounting Policy We determine if an arrangement is a lease at the inception of the agreement based on the terms and conditions in the contract. A contract contains a lease if there is an identified asset and we have the right to control the asset. We are the lessee for substantially all of our leasing activity, which primarily includes operating leases for office and warehouse space, tower space, vehicles and heavy equipment used in our operations. We are also a lessee in finance leases for service centers. We record a lease liability and a corresponding ROU asset for all of our leases with a term greater than 12 months. For lease contracts containing renewal and termination options, we include the option period in the lease term when it is reasonably certain the option will be exercised. We most frequently assume renewal options at the inception of the arrangement for our The ROU asset represents the right to use the underlying asset for the lease term, and is equal to the lease liability, adjusted for prepaid or accrued lease payments and any lease incentives that have been paid to us or when we are reasonably certain to incur costs equal to or greater than the allowance defined in the contract. Variable payments included in our leasing arrangements are expensed in the period in which the obligation for these payments is incurred. Variable payments are dependent on usage, output or may vary for other reasons. Most of our variable lease expense is related to tower leases that have escalating payments based on changes to a stated CPI index, and usage of certain office equipment. We have not provided material residual value guarantees for our leases, nor do our leases contain material restrictions or covenants. The lease liability represents the present value of all lease payments over the lease term. The discount rate used to determine the present value of the lease liability is the rate implicit in the lease unless that rate cannot be readily determined. We use the implicit rate stated in the agreement to determine the lease liability for our fleet leases. We use our corporate collateralized incremental borrowing rate as the discount rate for all other lease agreements. This rate is appropriate because we believe it represents the rate we would have incurred to borrow funds to acquire the leased asset over a similar term. We calculated this rate using a combination of inputs, including our current credit rating, quoted market prices of interest rates for our publicly traded unsecured debt, observable market yield curve data for peer companies with a credit rating one notch higher than our current credit rating and the lease term.
Earnings per share	Earnings Per Share We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock. Additionally, the weighted average shares outstanding for diluted EPS includes the incremental effects of the forward sale agreements, discussed in Note 8
Fair value measurement	Fair Value Measurements We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, 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 financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 . During the nine months ended June 30, 2020 , there were no changes in these methods.

Unaudited Financial Informati_3

Unaudited Financial Information (Table)	9 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Schedule of Regulatory Assets	Significant regulatory assets and liabilities as of June 30, 2020 and September 30, 2019 included the following: June 30, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 79,108 $ 86,089 Infrastructure mechanisms (1) 180,390 131,894 Deferred gas costs — 23,766 Recoverable loss on reacquired debt 5,259 6,551 Deferred pipeline record collection costs 28,700 26,418 Rate case costs 401 1,346 Other 6,173 8,483 $ 300,031 $ 284,547 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 723,400 $ 726,307 Regulatory cost of service reserve 2,559 5,238 Regulatory cost of removal obligation 528,932 528,893 Deferred gas costs 48,917 14,112 Asset retirement obligation 17,054 17,054 APT annual adjustment mechanism 62,461 78,402 Other 21,923 16,120 $ 1,405,246 $ 1,386,126 (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) Due to the passage of the Kansas House Bill 2585, on June 1, 2020, we remeasured our deferred tax liability and updated our state deferred tax rate resulting in a $12.1 million regulatory liability as of June 30, 2020 . See further details in Note 11. The remaining amount reflects the remeasurement of the net deferred tax liability included in our rate base as a result of the Tax Cuts and Jobs Act of 2017 (the "TCJA"). Of this amount, $20.9 million as of June 30, 2020 and $21.2 million as of September 30, 2019 is recorded in other current liabilities. These liabilities are being returned to customers in most of our jurisdictions on a provisional basis over 15 to 46 years until formal orders establish the final refund periods.
Schedule of Regulatory Liabilities	Significant regulatory assets and liabilities as of June 30, 2020 and September 30, 2019 included the following: June 30, September 30, (In thousands) Regulatory assets: Pension and postretirement benefit costs $ 79,108 $ 86,089 Infrastructure mechanisms (1) 180,390 131,894 Deferred gas costs — 23,766 Recoverable loss on reacquired debt 5,259 6,551 Deferred pipeline record collection costs 28,700 26,418 Rate case costs 401 1,346 Other 6,173 8,483 $ 300,031 $ 284,547 Regulatory liabilities: Regulatory excess deferred taxes (2) $ 723,400 $ 726,307 Regulatory cost of service reserve 2,559 5,238 Regulatory cost of removal obligation 528,932 528,893 Deferred gas costs 48,917 14,112 Asset retirement obligation 17,054 17,054 APT annual adjustment mechanism 62,461 78,402 Other 21,923 16,120 $ 1,405,246 $ 1,386,126 (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) Due to the passage of the Kansas House Bill 2585, on June 1, 2020, we remeasured our deferred tax liability and updated our state deferred tax rate resulting in a $12.1 million regulatory liability as of June 30, 2020 . See further details in Note 11. The remaining amount reflects the remeasurement of the net deferred tax liability included in our rate base as a result of the Tax Cuts and Jobs Act of 2017 (the "TCJA"). Of this amount, $20.9 million as of June 30, 2020 and $21.2 million as of September 30, 2019 is recorded in other current liabilities. These liabilities are being returned to customers in most of our jurisdictions on a provisional basis over 15 to 46 years until formal orders establish the final refund periods.

Segment Information (Table)

Segment Information (Table)	9 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Income statements and capital expenditures for the three and nine months ended June 30, 2020 and 2019 by segment are presented in the following tables: 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 Three Months Ended June 30, 2019 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 444,287 $ 41,451 $ — $ 485,738 Intersegment revenues 657 107,747 (108,404 ) — Total operating revenues 444,944 149,198 (108,404 ) 485,738 Purchased gas cost 139,518 (96 ) (108,096 ) 31,326 Operation and maintenance expense 123,998 40,855 (308 ) 164,545 Depreciation and amortization expense 70,611 27,089 — 97,700 Taxes, other than income 62,134 7,831 — 69,965 Operating income 48,683 73,519 — 122,202 Other non-operating income (expense) 3,005 (1,360 ) — 1,645 Interest charges 10,597 8,995 — 19,592 Income before income taxes 41,091 63,164 — 104,255 Income tax expense 8,693 15,096 — 23,789 Net income $ 32,398 $ 48,068 $ — $ 80,466 Capital expenditures $ 316,825 $ 104,788 $ — $ 421,613 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 Nine Months Ended June 30, 2019 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Operating revenues from external parties $ 2,339,660 $ 118,505 $ — $ 2,458,165 Intersegment revenues 2,008 300,813 (302,821 ) — Total operating revenues 2,341,668 419,318 (302,821 ) 2,458,165 Purchased gas cost 1,147,598 (544 ) (301,887 ) 845,167 Operation and maintenance expense 347,386 106,120 (934 ) 452,572 Depreciation and amortization expense 210,224 80,313 — 290,537 Taxes, other than income 189,377 24,169 — 213,546 Operating income 447,083 209,260 — 656,343 Other non-operating income (expense) 1,791 (3,637 ) — (1,846 ) Interest charges 44,703 29,687 — 74,390 Income before income taxes 404,171 175,936 — 580,107 Income tax expense 85,195 41,912 — 127,107 Net income $ 318,976 $ 134,024 $ — $ 453,000 Capital expenditures $ 912,640 $ 286,559 $ — $ 1,199,199 Balance sheet information at June 30, 2020 and September 30, 2019 by segment is presented in the following tables: June 30, 2020 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 9,644,503 $ 3,236,347 $ — $ 12,880,850 Total assets $ 14,098,715 $ 3,471,282 $ (2,699,015 ) $ 14,870,982 September 30, 2019 Distribution Pipeline and Storage Eliminations Consolidated (In thousands) Property, plant and equipment, net $ 8,737,590 $ 3,050,079 $ — $ 11,787,669 Total assets $ 12,579,741 $ 3,279,323 $ (2,491,445 ) $ 13,367,619

Earnings Per Share (Table)

Earnings Per Share (Table)	9 Months Ended
	Jun. 30, 2020
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, 2020 and 2019 are calculated as follows: Three Months Ended June 30 Nine Months Ended June 30 2020 2019 2020 2019 (In thousands, except per share amounts) Basic Earnings Per Share Net income $ 117,791 $ 80,466 $ 536,110 $ 453,000 Less: Income allocated to participating securities 88 64 408 386 Income available to common shareholders $ 117,703 $ 80,402 $ 535,702 $ 452,614 Basic weighted average shares outstanding 123,026 118,075 122,352 116,485 Net income per share — Basic $ 0.96 $ 0.68 $ 4.38 $ 3.89 Diluted Earnings Per Share Income available to common shareholders $ 117,703 $ 80,402 $ 535,702 $ 452,614 Effect of dilutive shares — — — — Income available to common shareholders $ 117,703 $ 80,402 $ 535,702 $ 452,614 Basic weighted average shares outstanding 123,026 118,075 122,352 116,485 Dilutive shares 6 355 111 188 Diluted weighted average shares outstanding 123,032 118,430 122,463 116,673 Net income per share - Diluted $ 0.96 $ 0.68 $ 4.37 $ 3.88

Revenue (Table)

Revenue (Table)	9 Months Ended
	Jun. 30, 2020
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, 2020 and 2019 . Three Months Ended June 30, 2020 Three Months Ended June 30, 2019 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 286,937 $ — $ 269,484 $ — Commercial 101,055 — 113,591 — Industrial 17,019 — 25,277 — Public authority and other 7,063 — 6,305 — Total gas sales revenues 412,074 — 414,657 — Transportation revenues 22,532 164,675 22,923 166,864 Miscellaneous revenues 2,793 2,277 6,125 2,407 Revenues from contracts with customers 437,399 166,952 443,705 169,271 Alternative revenue program revenues (1) (2,567 ) (8,944 ) 748 (20,073 ) Other revenues 476 — 491 — Total operating revenues $ 435,308 $ 158,008 $ 444,944 $ 149,198 Nine Months Ended June 30, 2020 Nine Months Ended June 30, 2019 Distribution Pipeline and Storage Distribution Pipeline and Storage (In thousands) Gas sales revenues: Residential $ 1,435,328 $ — $ 1,513,239 $ — Commercial 543,148 — 611,474 — Industrial 67,572 — 95,701 — Public authority and other 34,747 — 36,677 — Total gas sales revenues 2,080,795 — 2,257,091 — Transportation revenues 77,676 471,433 76,005 456,558 Miscellaneous revenues 16,565 8,767 20,439 6,862 Revenues from contracts with customers 2,175,036 480,200 2,353,535 463,420 Alternative revenue program revenues (1) 20,320 (27,779 ) (13,388 ) (44,102 ) Other revenues 1,461 — 1,521 — Total operating revenues $ 2,196,817 $ 452,421 $ 2,341,668 $ 419,318 (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 revenue benchmark.

Leases (Tables)

Leases (Tables)	9 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Other Pertinent Information Related to Leases	For the three and nine months ended June 30, 2020 , we did not have material short-term lease costs or variable lease costs. Three Months Ended June 30, 2020 Nine Months Ended June 30, 2020 (In thousands) Finance lease cost $ 197 $ 376 Operating lease cost 10,371 30,461 Total lease cost $ 10,568 $ 30,837 Our ROU assets and lease liabilities are presented as follows on the condensed consolidated balance sheets (unaudited): Balance Sheet Classification June 30, 2020 (In thousands) Assets Finance leases Net Property, Plant and Equipment $ 8,554 Operating leases Deferred charges and other assets 225,311 Total right-of-use assets $ 233,865 Liabilities Current Finance leases Current maturities of long-term debt $ 157 Operating leases Other current liabilities 33,884 Noncurrent Finance leases Long-term debt 8,479 Operating leases Deferred credits and other liabilities 200,390 Total lease liabilities $ 242,910 Other pertinent information related to leases was as follows. During the nine months ended June 30, 2020 , amounts paid in cash for our finance leases were not material. Nine Months Ended June 30, 2020 (In thousands) Cash paid amounts included in the measurement of lease liabilities Operating cash flows used for operating leases $ 28,011 Right-of-use assets obtained in exchange for lease obligations Finance leases $ 6,143 Operating leases $ 23,628 June 30, 2020 Weighted average remaining lease term (years) Finance leases 19.36 Operating leases 10.69 The following table represents our weighted average discount rate: June 30, 2020 Weighted average discount rate Finance leases 8.02 % Operating leases 2.91 %
Schedule of Finance Lease Liability Maturities	Maturities of our lease liabilities as of June 30, 2020 , presented on a rolling 12-month basis, were as follows: Total Finance Leases Operating Leases (In thousands) Year 1 $ 39,017 $ 738 $ 38,279 Year 2 37,983 749 37,234 Year 3 33,112 759 32,353 Year 4 26,386 770 25,616 Year 5 17,607 781 16,826 Thereafter 139,172 12,862 126,310 Total lease payments 293,277 16,659 276,618 Less: Imputed interest 50,367 8,023 42,344 Total $ 242,910 $ 8,636 $ 234,274 Reported as of June 30, 2020 Short-term lease liabilities $ 34,041 $ 157 $ 33,884 Long-term lease liabilities 208,869 8,479 200,390 Total lease liabilities $ 242,910 $ 8,636 $ 234,274
Schedule of Operating Lease Liability Maturities	Maturities of our lease liabilities as of June 30, 2020 , presented on a rolling 12-month basis, were as follows: Total Finance Leases Operating Leases (In thousands) Year 1 $ 39,017 $ 738 $ 38,279 Year 2 37,983 749 37,234 Year 3 33,112 759 32,353 Year 4 26,386 770 25,616 Year 5 17,607 781 16,826 Thereafter 139,172 12,862 126,310 Total lease payments 293,277 16,659 276,618 Less: Imputed interest 50,367 8,023 42,344 Total $ 242,910 $ 8,636 $ 234,274 Reported as of June 30, 2020 Short-term lease liabilities $ 34,041 $ 157 $ 33,884 Long-term lease liabilities 208,869 8,479 200,390 Total lease liabilities $ 242,910 $ 8,636 $ 234,274
Schedule of Future Minimum Lease Payments for Capital Leases	The future minimum lease payments as of September 30, 2019 were as follows: Operating Leases (1) Capital Lease (In thousands) 2020 $ 21,017 $ 243 2021 20,416 248 2022 19,370 253 2023 18,071 258 2024 15,718 263 Thereafter 105,544 4,343 Total minimum lease payments $ 200,136 5,608 Less amount representing interest 3,018 Present value of net minimum lease payments $ 2,590 (1) Future minimum lease payments do not include amounts for fleet leases and other de minimis items that can be renewed beyond the initial lease term. The Company anticipates renewing the leases beyond the initial term, but the anticipated payments associated with the renewals do not meet the definition of expected minimum lease payments and therefore are not included above. Expected payments are $17.6 million in 2020, $18.0 million in 2021, $11.8 million in 2022, $8.5 million in 2023, $5.4 million 2024 and $2.7 million thereafter.
Schedule of Future Minimum Rental Payments for Operating Leases	The future minimum lease payments as of September 30, 2019 were as follows: Operating Leases (1) Capital Lease (In thousands) 2020 $ 21,017 $ 243 2021 20,416 248 2022 19,370 253 2023 18,071 258 2024 15,718 263 Thereafter 105,544 4,343 Total minimum lease payments $ 200,136 5,608 Less amount representing interest 3,018 Present value of net minimum lease payments $ 2,590 (1) Future minimum lease payments do not include amounts for fleet leases and other de minimis items that can be renewed beyond the initial lease term. The Company anticipates renewing the leases beyond the initial term, but the anticipated payments associated with the renewals do not meet the definition of expected minimum lease payments and therefore are not included above. Expected payments are $17.6 million in 2020, $18.0 million in 2021, $11.8 million in 2022, $8.5 million in 2023, $5.4 million 2024 and $2.7 million thereafter.

Debt (Table)

Debt (Table)	9 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt at June 30, 2020 and September 30, 2019 consisted of the following: June 30, 2020 September 30, 2019 (In thousands) Unsecured 3.00% Senior Notes, due 2027 $ 500,000 $ 500,000 Unsecured 2.625% Senior Notes, due 2029 300,000 — 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 — Floating-rate term loan, due 2022 200,000 — 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 (see Note 6) 8,636 — Total long-term debt 4,568,636 3,560,000 Less: Original issue (premium) / discount on unsecured senior notes and debentures 623 193 Debt issuance cost 36,515 30,355 Current maturities 157 — $ 4,531,341 $ 3,529,452

Shareholders' Equity (Table)

Shareholders' Equity (Table)	9 Months Ended
	Jun. 30, 2020
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, 2020 and 2019 . 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 Common stock Additional Accumulated Retained Total Number of Stated (In thousands, except share and per share data) Balance, September 30, 2018 111,273,683 $ 556 $ 2,974,926 $ (83,647 ) $ 1,878,116 $ 4,769,951 Net income — — — — 157,646 157,646 Other comprehensive loss — — — (22,258 ) — (22,258 ) Cash dividends ($0.525 per share) — — — — (58,722 ) (58,722 ) Cumulative effect of accounting change — — — (8,210 ) 8,210 — Common stock issued: Public and other stock offerings 5,434,812 27 498,948 — — 498,975 Stock-based compensation plans 184,464 1 2,602 — — 2,603 Balance, December 31, 2018 116,892,959 584 3,476,476 (114,115 ) 1,985,250 5,348,195 Net income — — — — 214,888 214,888 Other comprehensive loss — — — (2,695 ) — (2,695 ) Cash dividends ($0.525 per share) — — — — (61,606 ) (61,606 ) Common stock issued: Public and other stock offerings 61,006 1 5,453 — — 5,454 Stock-based compensation plans 28,938 — 3,865 — — 3,865 Balance, March 31, 2019 116,982,903 585 3,485,794 (116,810 ) 2,138,532 5,508,101 Net income — — — — 80,466 80,466 Other comprehensive income — — — 1,147 — 1,147 Cash dividends ($0.525 per share) — — — — (61,654 ) (61,654 ) Common stock issued: Public and other stock offerings 1,127,244 5 103,425 — — 103,430 Stock-based compensation plans 85,966 1 10,505 — — 10,506 Balance, June 30, 2019 118,196,113 $ 591 $ 3,599,724 $ (115,663 ) $ 2,157,344 $ 5,641,996
Summary of Forward Sales Agreements	Additional details are presented below. Maturity Shares Available Net Proceeds Available Forward Price September 30, 2020 1,662,270 $ 174,142 $ 104.76 March 31, 2021 2,089,927 229,650 $ 109.88 June 30, 2021 1,394,423 143,430 $ 102.86 Total 5,146,620 $ 547,222
Schedule of Accumulated Other Comprehensive Income (Loss)	The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss). Available- for-Sale Securities Interest Rate Agreement Cash Flow Hedges Total (In thousands) September 30, 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 ) Available- for-Sale Securities Interest Rate Agreement Cash Flow Hedges Total (In thousands) September 30, 2018 $ 8,124 $ (91,771 ) $ (83,647 ) Other comprehensive income (loss) before reclassifications 192 (25,966 ) (25,774 ) Amounts reclassified from accumulated other comprehensive income (1 ) 1,969 1,968 Net current-period other comprehensive income (loss) 191 (23,997 ) (23,806 ) Cumulative effect of accounting change (8,210 ) — (8,210 ) June 30, 2019 $ 105 $ (115,768 ) $ (115,663 )

Interim Pension and Other Pos_2

Interim Pension and Other Postretirement Benefit Plan Information (Table)	9 Months Ended
	Jun. 30, 2020
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, 2020 and 2019 are presented in the following tables. Most of these costs are recoverable through our tariff rates. A portion of these costs is capitalized into our rate base or deferred as a regulatory asset or liability. The remaining costs are recorded as a component of operation and maintenance expense or other non-operating expense. Three Months Ended June 30 Pension Benefits Other Benefits 2020 2019 2020 2019 (In thousands) Components of net periodic pension cost: Service cost $ 4,652 $ 4,044 $ 3,366 $ 2,702 Interest cost (1) 5,843 6,799 2,653 2,960 Expected return on assets (1) (7,079 ) (7,113 ) (2,625 ) (2,664 ) Amortization of prior service cost (credit) (1) (58 ) (57 ) 43 43 Amortization of actuarial (gain) loss (1) 3,242 1,606 (334 ) (2,045 ) Net periodic pension cost $ 6,600 $ 5,279 $ 3,103 $ 996 Nine Months Ended June 30 Pension Benefits Other Benefits 2020 2019 2020 2019 (In thousands) Components of net periodic pension cost: Service cost $ 13,957 $ 12,134 $ 10,099 $ 8,107 Interest cost (1) 17,529 20,399 7,959 8,879 Expected return on assets (1) (21,237 ) (21,339 ) (7,874 ) (7,994 ) Amortization of prior service cost (credit) (1) (174 ) (173 ) 130 130 Amortization of actuarial (gain) loss (1) 9,725 4,821 (1,003 ) (6,134 ) Net periodic pension cost $ 19,800 $ 15,842 $ 9,311 $ 2,988 (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 financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2019 .

Financial Instruments (Table)

Financial Instruments (Table)	9 Months Ended
	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
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, 2020 and September 30, 2019 . 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, 2020 and September 30, 2019 , no gross amounts and no cash collateral were netted within our consolidated balance sheet. Balance Sheet Location Assets Liabilities (In thousands) June 30, 2020 Designated As Hedges: Interest rate swaps Other current assets / Other current liabilities $ 66 $ (5,305 ) Interest rate swaps Deferred charges and other assets / Deferred credits and other liabilities 4,181 (5,300 ) Total 4,247 (10,605 ) Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities 1,370 (461 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 247 (37 ) Total 1,617 (498 ) Gross / Net Financial Instruments $ 5,864 $ (11,103 ) Balance Sheet Location Assets Liabilities (In thousands) September 30, 2019 Not Designated As Hedges: Commodity contracts Other current assets / Other current liabilities $ 1,586 $ (4,552 ) Commodity contracts Deferred charges and other assets / Deferred credits and other liabilities 225 (1,249 ) Total 1,811 (5,801 ) Gross / Net Financial Instruments $ 1,811 $ (5,801 )
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, 2020 and 2019 . 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 2020 2019 2020 2019 (In thousands) Increase (decrease) in fair value: Interest rate agreements $ (4,932 ) $ — $ (4,932 ) $ (25,966 ) Recognition of losses in earnings due to settlements: Interest rate agreements 482 1,053 2,588 1,969 Total other comprehensive income (loss) from hedging, net of tax $ (4,450 ) $ 1,053 $ (2,344 ) $ (23,997 )
Schedule Of Expected Deferred Gains (Losses) Recognition	The following amounts, net of deferred taxes, represent the expected recognition in earnings, as of June 30, 2020 , of the deferred losses recorded in AOCI associated with our financial instruments, based upon the fair values of these financial instruments at the date of settlement. However, the table below does not include the expected recognition in earnings of our outstanding interest rate swaps as those instruments have not yet settled. Interest Rate Agreements (In thousands) Next twelve months $ (4,234 ) Thereafter (107,893 ) Total $ (112,127 )

Fair Value Measurements (Table)

Fair Value Measurements (Table)	9 Months Ended
	Jun. 30, 2020
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, 2020 and September 30, 2019 . Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral June 30, 2020 (In thousands) Assets: Financial instruments $ — $ 5,864 $ — $ — $ 5,864 Debt and equity securities Registered investment companies 37,229 — — — 37,229 Bond mutual funds 28,954 — — — 28,954 Bonds (2) — 34,408 — — 34,408 Money market funds — 5,126 — — 5,126 Total debt and equity securities 66,183 39,534 — — 105,717 Total assets $ 66,183 $ 45,398 $ — $ — $ 111,581 Liabilities: Financial instruments $ — $ 11,103 $ — $ — $ 11,103 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) (1) Significant Other Unobservable Inputs (Level 3) Netting and Cash Collateral September 30, 2019 (In thousands) Assets: Financial instruments $ — $ 1,811 $ — $ — $ 1,811 Debt and equity securities Registered investment companies 41,406 — — — 41,406 Bond mutual funds 25,966 — — — 25,966 Bonds (2) — 31,915 — — 31,915 Money market funds — 2,596 — — 2,596 Total debt and equity securities 67,372 34,511 — — 101,883 Total assets $ 67,372 $ 36,322 $ — $ — $ 103,694 Liabilities: Financial instruments $ — $ 5,801 $ — $ — $ 5,801 (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, 2020 and September 30, 2019 : June 30, 2020 September 30, 2019 (In thousands) Carrying Amount $ 4,560,000 $ 3,560,000 Fair Value $ 5,563,300 $ 4,216,249

Nature of Business (Details)

Nature of Business (Details) customer in Millions	Jun. 30, 2020customerstateregulated_distribution_division
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of customers serviced | customer	3,000,000
Number of regulated distribution divisions | regulated_distribution_division	6
Number of states with service areas | state	8

Unaudited Financial Informati_4

Unaudited Financial Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2019
Regulatory Asset [Line Items]
Regulatory assets	$ 300,031	$ 284,547
Regulatory Liabilities [Line Items]
Regulatory liabilities	1,405,246	1,386,126
Deferred Income Tax Charge - Remeasurement Due to Law Change under the Reg Liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	12,100
Regulatory excess deferred taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	723,400	726,307
Regulatory excess deferred taxes | Other Current Liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 20,900	21,200
Regulatory excess deferred taxes | Other Current Liabilities | Minimum
Regulatory Liabilities [Line Items]
Return basis, term	15 years
Regulatory excess deferred taxes | Other Current Liabilities | Maximum
Regulatory Liabilities [Line Items]
Return basis, term	46 years
Regulatory cost of service reserve
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 2,559	5,238
Regulatory cost of removal obligation
Regulatory Liabilities [Line Items]
Regulatory liabilities	528,932	528,893
Deferred gas costs
Regulatory Liabilities [Line Items]
Regulatory liabilities	48,917	14,112
Asset retirement obligation
Regulatory Liabilities [Line Items]
Regulatory liabilities	17,054	17,054
APT annual adjustment mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities	62,461	78,402
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	21,923	16,120
Pension and postretirement benefit costs
Regulatory Asset [Line Items]
Regulatory assets	79,108	86,089
Infrastructure mechanisms
Regulatory Asset [Line Items]
Regulatory assets	180,390	131,894
Deferred gas costs
Regulatory Asset [Line Items]
Regulatory assets	0	23,766
Recoverable loss on reacquired debt
Regulatory Asset [Line Items]
Regulatory assets	5,259	6,551
Deferred pipeline record collection costs
Regulatory Asset [Line Items]
Regulatory assets	28,700	26,418
Rate case costs
Regulatory Asset [Line Items]
Regulatory assets	401	1,346
Other
Regulatory Asset [Line Items]
Regulatory assets	$ 6,173	$ 8,483

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2020USD ($)state	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jun. 30, 2020USD ($)state	Jun. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Segment Reporting Information [Line Items]
Number of states with service areas | state	8						8
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	$ 492,995			$ 485,738			$ 2,346,223	$ 2,458,165
Purchased gas cost	26,072			31,326			640,823	845,167
Operation and maintenance expense	149,460			164,545			449,529	452,572
Depreciation and amortization expense	107,104			97,700			318,082	290,537
Taxes, other than income	71,324			69,965			214,535	213,546
Operating income	139,035			122,202			723,254	656,343
Other non-operating income	7,235			1,645			9,133	(1,846)
Interest charges	19,580			19,592			68,980	74,390
Income before income taxes	126,690			104,255			663,407	580,107
Income tax (benefit) expense	8,899			23,789			127,297	127,107
Net income	117,791	$ 239,646	$ 178,673	80,466	$ 214,888	$ 157,646	536,110	453,000
Capital expenditures	410,936			421,613			1,405,673	1,199,199
Segment Reporting Information, Balance Sheet [Abstract]
Property, plant and equipment, net	12,880,850						12,880,850		$ 11,787,669
Total assets	14,870,982						14,870,982		13,367,619
Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	434,650			444,287			2,194,786	2,339,660
Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	58,345			41,451			151,437	118,505
Operating Segments | Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	435,308			444,944			2,196,817	2,341,668
Purchased gas cost	126,093			139,518			942,586	1,147,598
Operation and maintenance expense	107,537			123,998			337,740	347,386
Depreciation and amortization expense	77,187			70,611			229,526	210,224
Taxes, other than income	61,980			62,134			190,636	189,377
Operating income	62,511			48,683			496,329	447,083
Other non-operating income	5,167			3,005			1,930	1,791
Interest charges	7,969			10,597			35,128	44,703
Income before income taxes	59,709			41,091			463,131	404,171
Income tax (benefit) expense	810			8,693			87,411	85,195
Net income	58,899			32,398			375,720	318,976
Capital expenditures	342,385			316,825			1,119,945	912,640
Segment Reporting Information, Balance Sheet [Abstract]
Property, plant and equipment, net	9,644,503						9,644,503		8,737,590
Total assets	14,098,715						14,098,715		12,579,741
Operating Segments | Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	158,008			149,198			452,421	419,318
Purchased gas cost	(11)			(96)			290	(544)
Operation and maintenance expense	42,234			40,855			112,751	106,120
Depreciation and amortization expense	29,917			27,089			88,556	80,313
Taxes, other than income	9,344			7,831			23,899	24,169
Operating income	76,524			73,519			226,925	209,260
Other non-operating income	2,068			(1,360)			7,203	(3,637)
Interest charges	11,611			8,995			33,852	29,687
Income before income taxes	66,981			63,164			200,276	175,936
Income tax (benefit) expense	8,089			15,096			39,886	41,912
Net income	58,892			48,068			160,390	134,024
Capital expenditures	68,551			104,788			285,728	286,559
Segment Reporting Information, Balance Sheet [Abstract]
Property, plant and equipment, net	3,236,347						3,236,347		3,050,079
Total assets	3,471,282						3,471,282		3,279,323
Intersegment eliminations
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	(100,321)			(108,404)			(303,015)	(302,821)
Purchased gas cost	(100,010)			(108,096)			(302,053)	(301,887)
Operation and maintenance expense	(311)			(308)			(962)	(934)
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 (benefit) 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	(2,699,015)						(2,699,015)		$ (2,491,445)
Intersegment eliminations | Distribution
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	658			657			2,031	2,008
Intersegment eliminations | Pipeline and Storage
Segment Reporting Information Profit Loss [Abstract]
Operating revenues	$ 99,663			$ 107,747			$ 300,984	$ 300,813

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, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019
Basic Earnings Per Share
Net income	$ 117,791	$ 239,646	$ 178,673	$ 80,466	$ 214,888	$ 157,646	$ 536,110	$ 453,000
Less: Income allocated to participating securities	88			64			408	386
Income available to common shareholders	$ 117,703			$ 80,402			$ 535,702	$ 452,614
Basic weighted average shares outstanding (in shares)	123,026			118,075			122,352	116,485
Net income per share - Basic (USD per share)	$ 0.96			$ 0.68			$ 4.38	$ 3.89
Diluted Earnings Per Share
Income available to common shareholders	$ 117,703			$ 80,402			$ 535,702	$ 452,614
Effect of dilutive shares	0			0			0	0
Income available to common shareholders	$ 117,703			$ 80,402			$ 535,702	$ 452,614
Basic weighted average shares outstanding (in shares)	123,026			118,075			122,352	116,485
Dilutive shares (in shares)	6			355			111	188
Diluted weighted average shares outstanding (in shares)	123,032			118,430			122,463	116,673
Net income per share - Diluted (USD per share)	$ 0.96			$ 0.68			$ 4.37	$ 3.88

Revenue (Details)

Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 492,995	$ 485,738	$ 2,346,223	$ 2,458,165
Regulatory mechanism threshold (in percent)			75.00%
Distribution
Disaggregation of Revenue [Line Items]
Total operating revenues	434,650	444,287	$ 2,194,786	2,339,660
Pipeline and Storage
Disaggregation of Revenue [Line Items]
Total operating revenues	58,345	41,451	151,437	118,505
Operating Segments | Distribution
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	437,399	443,705	2,175,036	2,353,535
Alternative revenue program revenues	(2,567)	748	20,320	(13,388)
Other Revenues	476	491	1,461	1,521
Total operating revenues	435,308	444,944	2,196,817	2,341,668
Operating Segments | Distribution | Gas sales revenues:
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	412,074	414,657	2,080,795	2,257,091
Operating Segments | Distribution | Gas sales revenues: | Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	286,937	269,484	1,435,328	1,513,239
Operating Segments | Distribution | Gas sales revenues: | Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	101,055	113,591	543,148	611,474
Operating Segments | Distribution | Gas sales revenues: | Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	17,019	25,277	67,572	95,701
Operating Segments | Distribution | Gas sales revenues: | Public authority and other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,063	6,305	34,747	36,677
Operating Segments | Distribution | Transportation revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	22,532	22,923	77,676	76,005
Operating Segments | Distribution | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,793	6,125	16,565	20,439
Operating Segments | Pipeline and Storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	166,952	169,271	480,200	463,420
Alternative revenue program revenues	(8,944)	(20,073)	(27,779)	(44,102)
Other Revenues	0	0	0	0
Total operating revenues	158,008	149,198	452,421	419,318
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	164,675	166,864	471,433	456,558
Operating Segments | Pipeline and Storage | Miscellaneous revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 2,277	$ 2,407	$ 8,767	$ 6,862

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2020	Oct. 01, 2019
Lessee, Lease, Description [Line Items]
Right-of-use asset			$ 225,311
Operating lease liabilities			$ 234,274
Lease and rental expense	$ 10,500	$ 30,700
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Right-of-use asset				$ 231,300
Operating lease liabilities				231,300
Accrued and prepaid rent reclassified				6,500
Deferred rent credits and other liabilities reclassified				$ 2,500

Leases - Weighted Averages (Det

Leases - Weighted Averages (Details)	Jun. 30, 2020
Leases [Abstract]
Finance lease, weighted average remaining lease term	19 years 4 months 9 days
Operating lease, weighted average remaining lease term	10 years 8 months 8 days
Finance lease, weighted average discount rate (in percent)	8.02%
Operating lease, weighted average discount rate (in percent)	2.91%

Leases - Income statement prese

Leases - Income statement presentation (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Lessee, Finance Lease, Description [Abstract]
Finance lease cost	$ 197	$ 376
Operating lease cost	10,371	30,461
Total lease cost	$ 10,568	$ 30,837

Leases - Balance sheet presenta

Leases - Balance sheet presentation (Details) $ in Thousands	Jun. 30, 2020USD ($)
Assets
Finance leases	$ 8,554
Operating leases	225,311
Total right-of-use assets	233,865
Current
Finance leases	157
Operating leases	33,884
Noncurrent
Finance leases	8,479
Operating leases	200,390
Total lease liabilities	$ 242,910
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PublicUtilitiesPropertyPlantAndEquipmentNet
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtAndCapitalLeaseObligations
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent

Leases - Other pertinent inform

Leases - Other pertinent information (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2020USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 28,011
Right-of-use assets obtained in exchange for lease obligations, Finance leases	6,143
Right-of-use assets obtained in exchange for lease obligations, Operating leases	$ 23,628

Leases - Maturities of lease li

Leases - Maturities of lease liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Year 1	$ 39,017
Year 2	37,983
Year 3	33,112
Year 4	26,386
Year 5	17,607
Thereafter	139,172
Total lease payments	293,277
Less: Imputed interest	50,367
Total lease liabilities	242,910
Short-term lease liabilities	34,041
Long-term lease liabilities	208,869
Finance Leases
Year 1	738
Year 2	749
Year 3	759
Year 4	770
Year 5	781
Thereafter	12,862
Total lease payments	16,659
Less: Imputed interest	8,023
Total	8,636	$ 0
Short-term lease liabilities	157
Long-term lease liabilities	8,479
Operating Leases
Year 1	38,279
Year 2	37,234
Year 3	32,353
Year 4	25,616
Year 5	16,826
Thereafter	126,310
Total lease payments	276,618
Less: Imputed interest	42,344
Total	234,274
Short-term lease liabilities	33,884
Long-term lease liabilities	$ 200,390

Leases - Future minimum lease p

Leases - Future minimum lease payments (Details) $ in Thousands	Sep. 30, 2019USD ($)
Lessee, Lease, Description [Line Items]
2020	$ 21,017
2021	20,416
2022	19,370
2023	18,071
2024	15,718
Thereafter	105,544
Total minimum lease payments	200,136
2020	243
2021	248
2022	253
2023	258
2024	263
Thereafter	4,343
Total minimum lease payments	5,608
Less amount representing interest	3,018
Present value of net minimum lease payments	2,590
Fleet Leases Renewed Beyond Initial Lease Term
Lessee, Lease, Description [Line Items]
2020	17,600
2021	18,000
2022	11,800
2023	8,500
2024	5,400
Thereafter	$ 2,700

Debt - Schedule of Long-term De

Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Oct. 02, 2019	Sep. 30, 2019
Debt Instrument [Line Items]
Long-term debt	$ 4,560,000		$ 3,560,000
Finance lease obligations	8,636		0
Total long-term debt	4,568,636		3,560,000
Original issue (premium) / discount on unsecured senior notes and debentures	623		193
Debt issuance cost	36,515		30,355
Current maturities	157		0
Long-term debt, noncurrent	$ 4,531,341		3,529,452
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%	2.625%
Long-term debt	$ 300,000		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%	3.375%
Long-term debt	$ 500,000		0
Floating-rate term loan, due 2022
Debt Instrument [Line Items]
Long-term debt	$ 200,000		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. 30, 2020USD ($)	Apr. 23, 2020USD ($)	Apr. 09, 2020USD ($)	Oct. 02, 2019USD ($)	Jun. 30, 2020USD ($)credit_facility	Apr. 01, 2020USD ($)	Sep. 30, 2019USD ($)
Line Of Credit Facility [Line Items]
Maximum borrowing capacity					$ 2,200,000,000
Maximum debt-to-total-capitalization ratio					70.00%
Debt-to-total-capitalization ratio					0.43
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]
Number of credit facilities | credit_facility					4
$200 Million Term Loan Agreement
Line Of Credit Facility [Line Items]
Debt agreement term			2 years
Unsecured 2.625% Senior Notes, due 2029
Line Of Credit Facility [Line Items]
Debt instrument, face amount				$ 300,000,000
Interest rate				2.625%	2.625%
Effective interest rate					2.72%
Unsecured 3.375% Senior Notes, due 2049
Line Of Credit Facility [Line Items]
Debt instrument, face amount				$ 500,000,000
Interest rate				3.375%	3.375%
Debt issuance cost				$ 791,700,000
Effective interest rate					3.42%
Five Year Unsecured Revolving Credit Agreement
Line Of Credit Facility [Line Items]
Outstanding commercial paper					$ 0		$ 464,900,000
Five Year Unsecured Revolving Credit Agreement | Commercial Paper
Line Of Credit Facility [Line Items]
Maximum borrowing capacity					1,500,000,000
Accordion feature					250,000,000
Maximum borrowing capacity post accordion feature					$ 1,750,000,000
Debt agreement term					5 years
$25 Million Bank Loan Agreement | Line of Credit
Line Of Credit Facility [Line Items]
Maximum borrowing capacity					$ 25,000,000
Debt agreement term					364 days
$50 Million Bank Loan Agreement | Line of Credit
Line Of Credit Facility [Line Items]
Maximum borrowing capacity						$ 50,000,000
Outstanding borrowings					$ 0
$10 Million Revolving Credit Note | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity					$ 10,000,000
Debt agreement term					364 days
$50 Million Revolving Credit Facility | Revolving Credit Facility
Line Of Credit Facility [Line Items]
Maximum borrowing capacity	$ 50,000,000				$ 50,000,000
Debt agreement term	364 days
Remaining borrowing capacity					44,400,000
$50 Million Revolving Credit Facility | Line of Credit
Line Of Credit Facility [Line Items]
Outstanding borrowings					0
$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
Outstanding borrowings					$ 0
LIBOR | Five Year Unsecured Revolving Credit Agreement | Commercial Paper | Minimum
Line Of Credit Facility [Line Items]
Interest rate spread					0.00%
LIBOR | Five Year Unsecured Revolving Credit Agreement | Commercial Paper | Maximum
Line Of Credit Facility [Line Items]
Interest rate spread					1.25%
LIBOR | $600 Million Revolving Credit Facility | Revolving Credit Facility | Minimum
Line Of Credit Facility [Line Items]
Interest rate spread		0.00%
LIBOR | $600 Million Revolving Credit Facility | Revolving Credit Facility | Maximum
Line Of Credit Facility [Line Items]
Interest rate spread		1.25%
Secured Debt | $200 Million Term Loan Agreement
Line Of Credit Facility [Line Items]
Debt instrument, face amount			$ 200,000,000
Secured Debt | LIBOR | $200 Million Term Loan Agreement
Line Of Credit Facility [Line Items]
Interest rate spread			1.25%

Shareholders' Equity - Componen

Shareholders' Equity - Components of Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding (in shares)			119,338,925				119,338,925
Shareholders' equity, beginning balance	$ 6,304,415	$ 6,127,775	$ 5,750,223	$ 5,508,101	$ 5,348,195	$ 4,769,951	$ 5,750,223	$ 4,769,951
Net income	117,791	239,646	178,673	80,466	214,888	157,646	536,110	453,000
Other comprehensive income (loss)	(4,086)	890	1,052	1,147	(2,695)	(22,258)	$ (2,144)	(23,806)
Cash dividends	(70,597)	(70,520)	(69,557)	(61,654)	(61,606)	(58,722)
Public and other stock offerings	105,804	3,096	263,272	103,430	5,454	498,975
Stock-based compensation plans	$ 8,144	3,528	4,112	10,506	3,865	2,603
Common stock outstanding (in shares)	123,351,267						123,351,267
Shareholders' equity, ending balance	$ 6,461,471	$ 6,304,415	$ 6,127,775	$ 5,641,996	$ 5,508,101	$ 5,348,195	$ 6,461,471	$ 5,641,996
Cash dividends per share (USD per share)	$ 0.575	$ 0.575	$ 0.575	$ 0.525	$ 0.525	$ 0.525	$ 1.725	$ 1.575
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock outstanding (in shares)	122,308,725	122,262,403	119,338,925	116,982,903	116,892,959	111,273,683	119,338,925	111,273,683
Shareholders' equity, beginning balance	$ 612	$ 611	$ 597	$ 585	$ 584	$ 556	$ 597	$ 556
Public and other stock offerings (in shares)	965,576	38,662	2,758,929	1,127,244	61,006	5,434,812
Public and other stock offerings	$ 5	$ 1	$ 13	$ 5	$ 1	$ 27
Stock-based compensation plans (in shares)	76,966	7,660	164,549	85,966	28,938	184,464
Stock-based compensation plans	$ 0	$ 0	$ 1	$ 1	$ 0	$ 1
Common stock outstanding (in shares)	123,351,267	122,308,725	122,262,403	118,196,113	116,982,903	116,892,959	123,351,267	118,196,113
Shareholders' equity, ending balance	$ 617	$ 612	$ 611	$ 591	$ 585	$ 584	$ 617	$ 591
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	3,986,187	3,979,564	3,712,194	3,485,794	3,476,476	2,974,926	3,712,194	2,974,926
Public and other stock offerings	105,799	3,095	263,259	103,425	5,453	498,948
Stock-based compensation plans	8,144	3,528	4,111	10,505	3,865	2,602
Shareholders' equity, ending balance	4,100,130	3,986,187	3,979,564	3,599,724	3,485,794	3,476,476	4,100,130	3,599,724
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	(112,641)	(113,531)	(114,583)	(116,810)	(114,115)	(83,647)	(114,583)	(83,647)
Other comprehensive income (loss)	(4,086)	890	1,052	1,147	(2,695)	(22,258)
Shareholders' equity, ending balance	(116,727)	(112,641)	(113,531)	(115,663)	(116,810)	(114,115)	(116,727)	(115,663)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance	2,430,257	2,261,131	2,152,015	2,138,532	1,985,250	1,878,116	2,152,015	1,878,116
Net income	117,791	239,646	178,673	80,466	214,888	157,646
Cash dividends	(70,597)	(70,520)	(69,557)	(61,654)	(61,606)	(58,722)
Shareholders' equity, ending balance	$ 2,477,451	$ 2,430,257	$ 2,261,131	$ 2,157,344	$ 2,138,532	1,985,250	$ 2,477,451	2,157,344
Cumulative effect of accounting change
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance						(8,210)		(8,210)
Cumulative effect of accounting change | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance						(8,210)		(8,210)
Cumulative effect of accounting change | Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity, beginning balance						$ 8,210		$ 8,210

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details)	Nov. 30, 2018USD ($)Forward_sellershares	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2019USD ($)shares	Feb. 12, 2020USD ($)	Feb. 11, 2020USD ($)
Class of Stock [Line Items]
Value of shares authorized				$ 1,000,000,000
Forward contract indexed to issuer's equity, settlement alternatives, cash, at fair value		$ 547,222,000
Net proceeds from equity offering		358,047,000	$ 593,731,000
Number of forward sellers | Forward_seller	2
Shelf Registration Statement
Class of Stock [Line Items]
Debt and equity securities authorized for issuance					$ 4,000,000,000
Debt and equity securities authorized for issuance value remaining		$ 3,000,000,000
At-The-Market
Class of Stock [Line Items]
Forward sales equity agreement (in shares) | shares	2,668,464	4,148,057	2,721,072
Forward contract indexed to issuer's equity, settlement alternatives, cash, at fair value		$ 453,900,000
Stock issued during period, new issues (in shares) | shares		3,146,108
Net proceeds from equity offering		$ 314,600,000
Equity available for issuance		621,000,000
Common Stock Block Trade
Class of Stock [Line Items]
Stock issued during period, new issues (in shares) | shares	5,390,836
Net proceeds from equity offering	$ 494,100,000
Proceeds from issuance of common stock gross	500,000,000
Forward Sales Equity Agreements
Class of Stock [Line Items]
Forward contract indexed to issuer's equity, settlement alternatives, cash, at fair value	$ 247,500,000	$ 547,200,000	$ 268,700,000
Stock issued during period, new issues (in shares) | shares		485,189
Net proceeds from equity offering		$ 44,400,000
Forward sales equity agreement, forward rate per share | $ / shares		$ 106.33
Forward Sales Equity, Maturity March 2020 | Common Stock Block Trade
Class of Stock [Line Items]
Stock issued during period, new issues (in shares) | shares			1,089,700
Net proceeds from equity offering			$ 99,600,000

Shareholders' Equity - Forward

Shareholders' Equity - Forward Sales Agreement (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Jun. 30, 2020USD ($)$ / sharesshares
Class of Stock [Line Items]
Shares Available (in shares) | shares	5,146,620
Net Proceeds Available | $	$ 547,222
September 30, 2020
Class of Stock [Line Items]
Shares Available (in shares) | shares	1,662,270
Net Proceeds Available | $	$ 174,142
Forward Price (dollars per share) | $ / shares	$ 104.76
March 31, 2021
Class of Stock [Line Items]
Shares Available (in shares) | shares	2,089,927
Net Proceeds Available | $	$ 229,650
Forward Price (dollars per share) | $ / shares	$ 109.88
June 30, 2021
Class of Stock [Line Items]
Shares Available (in shares) | shares	1,394,423
Net Proceeds Available | $	$ 143,430
Forward Price (dollars per share) | $ / shares	$ 102.86

Shareholders' Equity - Schedule

Shareholders' Equity - Schedule of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	$ 6,304,415	$ 6,127,775	$ 5,750,223	$ 5,508,101	$ 5,348,195	$ 4,769,951	$ 5,750,223	$ 4,769,951
Other comprehensive income (loss) before reclassifications							(4,730)	(25,774)
Amounts reclassified from accumulated other comprehensive income							2,586	1,968
Net current-period other comprehensive income (loss)	(4,086)	890	1,052	1,147	(2,695)	(22,258)	(2,144)	(23,806)
Shareholders' equity, ending balance	6,461,471	6,304,415	6,127,775	5,641,996	5,508,101	5,348,195	6,461,471	5,641,996
Available- for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance			132			8,124	132	8,124
Other comprehensive income (loss) before reclassifications							202	192
Amounts reclassified from accumulated other comprehensive income							(2)	(1)
Net current-period other comprehensive income (loss)							200	191
Shareholders' equity, ending balance	332			105			332	105
Interest Rate Agreement Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance			(114,715)			(91,771)	(114,715)	(91,771)
Other comprehensive income (loss) before reclassifications							(4,932)	(25,966)
Amounts reclassified from accumulated other comprehensive income							2,588	1,969
Net current-period other comprehensive income (loss)							(2,344)	(23,997)
Shareholders' equity, ending balance	(117,059)			(115,768)			(117,059)	(115,768)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance	(112,641)	(113,531)	(114,583)	(116,810)	(114,115)	(83,647)	(114,583)	(83,647)
Net current-period other comprehensive income (loss)	(4,086)	890	1,052	1,147	(2,695)	(22,258)
Shareholders' equity, ending balance	$ (116,727)	$ (112,641)	$ (113,531)	$ (115,663)	$ (116,810)	(114,115)	$ (116,727)	(115,663)
Cumulative effect of accounting change
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance						(8,210)		(8,210)
Cumulative effect of accounting change | Available- for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance						(8,210)		(8,210)
Cumulative effect of accounting change | Interest Rate Agreement Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance						0		0
Cumulative effect of accounting change | Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Shareholders' equity, beginning balance						$ (8,210)		$ (8,210)

Interim Pension and Other Pos_3

Interim Pension and Other Postretirement Benefit Plan Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Contribution to postretirement medical plans			$ 12,200
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4,652	$ 4,044	13,957	$ 12,134
Interest cost	5,843	6,799	17,529	20,399
Expected return on assets	(7,079)	(7,113)	(21,237)	(21,339)
Amortization of prior service cost (credit)	(58)	(57)	(174)	(173)
Amortization of actuarial (gain) loss	3,242	1,606	9,725	4,821
Net periodic pension cost	6,600	5,279	19,800	15,842
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	3,366	2,702	10,099	8,107
Interest cost	2,653	2,960	7,959	8,879
Expected return on assets	(2,625)	(2,664)	(7,874)	(7,994)
Amortization of prior service cost (credit)	43	43	130	130
Amortization of actuarial (gain) loss	(334)	(2,045)	(1,003)	(6,134)
Net periodic pension cost	3,103	$ 996	9,311	$ 2,988
Minimum | Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions	10,000		10,000
Maximum | Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions	$ 20,000		$ 20,000

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	9 Months Ended
	Jun. 30, 2020USD ($)Bcf
Commitments and Contingencies Disclosure [Abstract]
Self-insurance retention expense | $	$ 1
Short-term Contract with Customer | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, minimum volume required	59.3
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	71.5
Long-term Contract with Customer Beyond Three Years | Supply Commitment
Long-term Purchase Commitment [Line Items]
Long-term purchase commitment, minimum volume required	0.2

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Sep. 30, 2019
Income Tax Contingency [Line Items]
Reduction of deferred tax liability	$ 32,500
Regulatory liabilities	1,405,246	$ 1,405,246	$ 1,386,126
Income tax benefit	21,000	21,000
Deferred Income Tax Charge - Remeasurement Due to Law Change under the Reg Liability
Income Tax Contingency [Line Items]
Regulatory liabilities	$ 12,100	$ 12,100

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	3 Months Ended		6 Months Ended	9 Months Ended
	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2020Bcf	Jun. 30, 2020USD ($)Bcf	Jun. 30, 2019USD ($)	Sep. 30, 2025	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Jul. 31, 2020USD ($)	Sep. 30, 2019USD ($)
Derivative [Line Items]
Net realized gain (loss) in AOCI	$ (112,100,000)			$ (112,100,000)
Contract Netting	0			0							$ 0
Cash collateral	0			0							$ 0
Net gain (loss) on settled interest rate agreements	(1,400,000)	$ (1,400,000)		(4,100,000)	$ (2,600,000)
Designated as Hedging Instrument | Forward Interest Rate Swap 1
Derivative [Line Items]
Derivative, notional amount	500,000,000			500,000,000
Designated as Hedging Instrument | Forward Interest Rate Swap 2
Derivative [Line Items]
Derivative, notional amount	$ 450,000,000			$ 450,000,000
Gas Purchases | Not Designated as Hedging Instrument | Commodity contracts
Derivative [Line Items]
Hedging percent			49.00%
Energy measure | Bcf			19.9
Gas Purchases | Not Designated as Hedging Instrument | Commodity contracts | Long
Derivative [Line Items]
Energy measure | Bcf				10.05
Minimum | Gas Purchases | Not Designated as Hedging Instrument | Commodity contracts
Derivative [Line Items]
Hedging percent	25.00%			25.00%
Maximum | Gas Purchases | Not Designated as Hedging Instrument | Commodity contracts
Derivative [Line Items]
Hedging percent	50.00%			50.00%
Forecast | Unsecured Senior Notes In Fiscal 2023
Derivative [Line Items]
Interest rate							1.36%
Forecast | Unsecured Senior Notes In Fiscal 2025
Derivative [Line Items]
Interest rate						1.35%
Forecast | Unsecured Senior Notes In Fiscal 2021
Derivative [Line Items]
Interest rate									0.69%
Forecast | Unsecured Senior Notes In Fiscal 2022
Derivative [Line Items]
Interest rate								1.33%
Subsequent Event | Designated as Hedging Instrument | Forward Interest Rate Swap 3
Derivative [Line Items]
Derivative, notional amount										$ 300,000,000
Subsequent Event | Designated as Hedging Instrument | Forward Interest Rate Swap 4
Derivative [Line Items]
Derivative, notional amount										$ 300,000,000

Financial Instruments - Schedul

Financial Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Derivatives Fair Value [Line Items]
Net Financial Instruments, Assets	$ 5,864	$ 1,811
Net Financial Instruments, Liabilities	(11,103)	(5,801)
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	4,247
Gross Financial Instruments, Liabilities	(10,605)
Designated as Hedging Instrument | Other Current Assets | Interest rate swaps
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	66
Designated as Hedging Instrument | Other Current Liabilities | Interest rate swaps
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	(5,305)
Designated as Hedging Instrument | Deferred Charges and Other Assets | Interest rate swaps
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	4,181
Designated as Hedging Instrument | Deferred Credits and Other Liabilities | Interest rate swaps
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	(5,300)
Not Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	1,617	1,811
Gross Financial Instruments, Liabilities	(498)	(5,801)
Not Designated as Hedging Instrument | Other Current Assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	1,370	1,586
Not Designated as Hedging Instrument | Other Current Liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	(461)	(4,552)
Not Designated as Hedging Instrument | Deferred Charges and Other Assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Assets	247	225
Not Designated as Hedging Instrument | Deferred Credits and Other Liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross Financial Instruments, Liabilities	$ (37)	$ (1,249)

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Increase (decrease) in fair value:
Interest rate agreements	$ (4,932)	$ 0	$ (4,932)	$ (25,966)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Interest rate agreements	482	1,053	2,588	1,969
Total other comprehensive income (loss) from hedging, net of tax	$ (4,450)	$ 1,053	$ (2,344)	$ (23,997)

Financial Instruments - Sched_3

Financial Instruments - Schedule Of Expected Deferred Gains (Losses) Recognition (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2020USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Next twelve months	$ (4,234)
Thereafter	(107,893)
Total	$ (112,127)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Jun. 30, 2020	Sep. 30, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Netting and Cash Collateral	$ 0	$ 0
Financial instruments net assets	5,864,000	1,811,000
Debt and equity securities	105,717,000	101,883,000
Total assets	111,581,000	103,694,000
Netting and Cash Collateral	0	0
Financial instruments net liability	11,103,000	5,801,000
Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	37,229,000	41,406,000
Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	28,954,000	25,966,000
Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	34,408,000	31,915,000
Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	5,126,000	2,596,000
Fair Value Inputs Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial instruments gross assets	0	0
Debt and equity securities	66,183,000	67,372,000
Total assets	66,183,000	67,372,000
Financial instruments gross liability	0	0
Fair Value Inputs Level 1 | Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	37,229,000	41,406,000
Fair Value Inputs Level 1 | Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	28,954,000	25,966,000
Fair Value Inputs Level 1 | Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	0	0
Fair Value Inputs Level 1 | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	0	0
Fair Value Inputs Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial instruments gross assets	5,864,000	1,811,000
Debt and equity securities	39,534,000	34,511,000
Total assets	45,398,000	36,322,000
Financial instruments gross liability	11,103,000	5,801,000
Fair Value Inputs Level 2 | Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	0	0
Fair Value Inputs Level 2 | Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	0	0
Fair Value Inputs Level 2 | Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	34,408,000	31,915,000
Fair Value Inputs Level 2 | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	5,126,000	2,596,000
Fair Value 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
Fair Value Inputs Level 3 | Registered investment companies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	0	0
Fair Value Inputs Level 3 | Bond mutual funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Equity Securities	0	0
Fair Value Inputs Level 3 | Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt securities	0	0
Fair Value 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 ($) $ in Millions	Jun. 30, 2020	Sep. 30, 2019
Schedule of Available For Sale Securities [Abstract]
Cost Basis	$ 34	$ 31.7

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Carrying Amount	$ 4,560,000	$ 3,560,000
Fair Value	$ 5,563,300	$ 4,216,249