ATMOS ENERGY CORP, 10-Q filed on 8/5/2026
Quarterly Report
v3.26.1
Cover Page - shares
 9 Months Ended
Jun. 30, 2026
Jul. 31, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
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)   168,988,553
Entity Central Index Key 0000731802  
Current Fiscal Year End Date --09-30  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q3  
Amendment Flag false  
v3.26.1
CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
ASSETS    
Property, plant and equipment $ 32,221,314 $ 29,264,136
Less accumulated depreciation and amortization 4,205,704 3,971,146
Net property, plant and equipment 28,015,610 25,292,990
Current assets    
Cash and cash equivalents 520,953 202,687
Restricted cash and cash equivalents 4,856 1,116
Cash and cash equivalents and restricted cash and cash equivalents 525,809 203,803
Accounts receivable, net 469,455 375,509
Gas stored underground 154,429 171,756
Other current assets 351,150 301,627
Total current assets 1,500,843 1,052,695
Securitized intangible asset, net (See Note 9) 68,026 75,127
Goodwill 731,257 731,257
Deferred charges and other assets 1,269,803 1,097,453
Total assets 31,585,539 28,249,522
Shareholders’ equity    
Common stock, no par value (stated at $0.005 per share), June 30, 2026 — authorized: 400,000,000 shares, issued and outstanding: 168,986,249 shares; September 30, 2025 — authorized: 200,000,000, issued and outstanding: 161,568,384 shares 845 808
Additional paid-in capital 9,205,951 8,221,455
Accumulated other comprehensive income 460,407 475,015
Retained earnings 5,590,855 4,861,612
Shareholders’ equity 15,258,058 13,558,890
Long-term debt, net 9,748,716 8,907,169
Securitized long-term debt (See Note 9) 63,751 68,236
Total capitalization 25,070,525 22,534,295
Current liabilities    
Accounts payable and accrued liabilities 436,664 506,516
Other current liabilities 896,311 835,557
Current maturities of long-term debt 502,542 11,775
Current maturities of securitized long-term debt (See Note 9) 8,858 8,767
Total current liabilities 1,844,375 1,362,615
Deferred income taxes 3,262,989 2,918,347
Regulatory excess deferred taxes 100,285 117,482
Regulatory cost of removal obligation 493,006 532,461
Deferred credits and other liabilities 814,359 784,322
Total capitalization and liabilities $ 31,585,539 $ 28,249,522
v3.26.1
CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares
Jun. 30, 2026
Sep. 30, 2025
Statement of Financial Position [Abstract]    
Common stock stated value (USD per share) $ 0.005 $ 0.005
Common stock authorized (in shares) 400,000,000 200,000,000
Common stock issued (in shares) 168,986,249 161,568,384
Common stock outstanding (in shares) 168,986,249 161,568,384
v3.26.1
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
shares in Thousands, $ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Operating revenues $ 879,059 $ 838,774 $ 4,184,046 $ 3,965,275
Purchased gas cost 8,213 53,840 971,530 1,067,121
Operation and maintenance expense 223,162 222,100 648,762 662,440
Depreciation and amortization expense 201,521 185,786 591,853 549,069
Taxes, other than income 125,749 124,981 371,919 346,159
Operating income 320,414 252,067 1,599,982 1,340,486
Other non-operating income 16,013 20,100 55,760 68,906
Interest charges 33,144 41,537 115,288 144,476
Income before income taxes 303,283 230,630 1,540,454 1,264,916
Income tax expense 60,594 44,201 312,902 241,053
Net income $ 242,689 $ 186,429 $ 1,227,552 $ 1,023,863
Basic net income per share (USD per share) $ 1.44 $ 1.17 $ 7.40 $ 6.47
Diluted net income per share (USD per share) 1.43 1.16 7.33 6.40
Cash dividends per share (USD per share) $ 1.00 $ 0.87 $ 3.00 $ 2.61
Basic weighted average shares outstanding (in shares) 168,345 159,285 165,845 158,245
Diluted weighted average shares outstanding (in shares) 169,374 161,171 167,352 159,798
Other comprehensive income (loss), net of tax        
Net unrealized holding gains (losses) on available-for-sale securities, net of tax $ (85) $ 31 $ (242) $ (34)
Cash flow hedges:        
Amortization and unrealized gains (losses) on interest rate agreements, net of tax (4,780) 1,378 (14,366) 12,279
Total other comprehensive income (loss) (4,865) 1,409 (14,608) 12,245
Total comprehensive income 237,824 187,838 1,212,944 1,036,108
Distribution segment        
Operating revenues 773,909 766,380 3,908,869 3,756,691
Depreciation and amortization expense 148,349 137,106 441,088 405,279
Interest charges 12,870 22,271 66,445 86,607
Income tax expense 15,558 9,731 186,414 147,833
Net income 89,385 70,481 795,923 691,337
Pipeline and storage segment        
Operating revenues 105,150 72,394 275,177 208,584
Depreciation and amortization expense 53,172 48,680 150,765 143,790
Interest charges 20,274 19,266 48,843 57,869
Income tax expense 45,036 34,470 126,488 93,220
Net income 153,304 115,948 431,629 332,526
Operating Segments        
Operating revenues 1,107,711 1,039,520 4,820,139 4,545,772
Operating Segments | Distribution segment        
Operating revenues 774,658 767,132 3,911,164 3,758,995
Purchased gas cost 237,072 255,883 1,605,020 1,647,490
Operating Segments | Pipeline and storage segment        
Operating revenues 333,053 272,388 908,975 786,777
Purchased gas cost (452) (1,548) 1,836 (638)
Intersegment eliminations        
Operating revenues (228,652) (200,746) (636,093) (580,497)
Purchased gas cost (228,407) (200,495) (635,326) (579,731)
Intersegment eliminations | Distribution segment        
Operating revenues (749) (752) (2,295) (2,304)
Intersegment eliminations | Pipeline and storage segment        
Operating revenues $ (227,903) $ (199,994) $ (633,798) $ (578,193)
v3.26.1
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Income Statement [Abstract]        
Net unrealized holding gains (losses) on available-for-sale securities, tax $ (24) $ 9 $ (69) $ (13)
Amortization and unrealized gains (losses) on interest rate agreements, tax $ (1,366) $ 394 $ (4,070) $ 2,264
v3.26.1
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands
 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Cash Flows From Operating Activities    
Net income $ 1,227,552 $ 1,023,863
Adjustments to reconcile net income to net cash provided by operating activities:    
Depreciation and amortization expense 591,853 549,069
Deferred income taxes 300,650 214,609
Other (50,435) (49,402)
Net assets / liabilities from risk management activities 1,417 (1,966)
Net change in other operating assets and liabilities (399,571) (34,841)
Net cash provided by operating activities 1,671,466 1,701,332
Cash Flows From Investing Activities    
Capital expenditures (3,076,281) (2,597,787)
Debt and equity securities activities, net (6,168) (2,348)
Other, net 6,317 6,469
Net cash used in investing activities (3,076,132) (2,593,666)
Cash Flows From Financing Activities    
Net proceeds from equity issuances 941,694 568,603
Issuance of common stock through stock purchase and employee retirement plans 4,783 11,532
Proceeds from issuance of long-term debt 1,296,231 1,143,447
Repayment of long-term debt (10,000) 0
Repayment of securitized long-term debt by AEK (4,394) (4,051)
Cash dividends paid (490,698) (412,312)
Debt issuance costs (10,944) (10,140)
Net cash provided by financing activities 1,726,672 1,297,079
Net increase in cash and cash equivalents and restricted cash and cash equivalents 322,006 404,745
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period 203,803 308,856
Cash and cash equivalents and restricted cash and cash equivalents at end of period $ 525,809 $ 713,601
v3.26.1
Nature of Business
 9 Months Ended
Jun. 30, 2026
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 approximately 3.4 million residential, commercial, public authority, and industrial customers through our six regulated distribution divisions, which at June 30, 2026, 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.
v3.26.1
Summary of Significant Accounting Policies
 9 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]  
Summary of Significant Accounting Policies Summary of Significant Accounting Policies
Basis of presentation
These consolidated interim-period financial statements have been prepared in accordance with accounting principles generally accepted in the United States on the same basis as those used for the Company’s audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. 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, 2025. Because of seasonal and other factors, the results of operations for the nine-month period ended June 30, 2026 are not indicative of our results of operations for the full 2026 fiscal year, which ends September 30, 2026.
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, 2025.
During the second quarter of fiscal 2026, we completed our annual goodwill impairment assessment using a qualitative assessment, as permitted under U.S. GAAP. We test for goodwill impairment at the reporting unit level on an annual basis and between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of the reporting unit. Based on the assessment performed, we determined that our goodwill was not impaired.
No events have occurred subsequent to the balance sheet date that would require recognition or disclosure in the condensed consolidated financial statements.
Recently issued accounting pronouncements
In November 2024, the FASB issued guidance that will require more detailed information about the types of expenses in commonly presented expense captions. The amendment is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. This amendment will be effective for our Form 10-K for fiscal 2028 and our Form 10-Q for the first quarter of fiscal 2029. We are currently evaluating the impact this may have on our financial statement disclosures.
In September 2025, the FASB issued guidance which provides qualitative updates to the determination of capitalizing internal-use software costs by expanding the scope to allow for various software development methods. The amendment is effective for fiscal years beginning after December 15, 2027. Early adoption is permitted, and the amendment may be applied prospectively, retrospectively, or with a modified transition approach. This amendment will be effective for our Form 10-K for fiscal 2029 and our Form 10-Q for the first quarter of fiscal 2029. We are currently evaluating the impact this may have on our financial statement disclosures.
v3.26.1
Regulation
 9 Months Ended
Jun. 30, 2026
Regulated Operations [Abstract]  
Regulation Regulation
Accounting principles generally accepted in the United States require cost-based, rate-regulated entities that meet certain criteria to reflect the authorized recovery of costs due to regulatory decisions in their financial statements. As a result, certain
costs are permitted to be capitalized rather than expensed because they can be recovered through rates. We record certain costs as regulatory assets when future recovery through customer rates is considered probable. Regulatory liabilities are recorded when it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process. Substantially all of our regulatory assets are recorded as a component of other current assets and deferred charges and other assets and our regulatory liabilities are recorded as a component of other current liabilities and deferred credits and other liabilities. Deferred gas costs are recorded either in other current assets or liabilities.
Regulatory assets and liabilities as of June 30, 2026 and September 30, 2025 included the following:
June 30,
2026		September 30,
2025
(In thousands)
Regulatory assets:
Pension and postretirement benefit costs$3,857 $262 
Infrastructure mechanisms (1)
425,281 314,047 
Winter Storm Uri incremental costs1,141 5,841 
Deferred gas costs156,975 140,626 
Regulatory excess deferred taxes (2)
48,718 49,793 
Recoverable loss on reacquired debt2,777 2,903 
Deferred pipeline record collection costs35,642 39,035 
System Safety and Integrity Riders (3)
48,801 43,625 
Other18,439 12,597 
$741,631 $608,729 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$134,694 $190,274 
Regulatory cost of removal obligation645,942 641,019 
Deferred gas costs6,844 6,879 
APT annual adjustment mechanism182,546 99,393 
Pension and postretirement benefit costs289,505 291,351 
Other34,542 40,732 
$1,294,073 $1,269,648 
(1)Texas, Louisiana, and Tennessee have authorized infrastructure mechanisms that mitigate regulatory lag and allow for the deferral of eligible incurred costs related to qualifying capital expenditures until new rates are implemented. The investment and deferred costs are required to be included in the Company's next rate filing (rate case or annual rate filing) for recovery through base rates.
(2)Regulatory excess deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of the Tax Cuts and Jobs Act of 2017 (the "TCJA"), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. See Note 12 to the condensed consolidated financial statements for further information.
(3)In our APT and West Texas Divisions and portions of our Mid-Tex Division, the RRC has approved the deferral of certain system safety and integrity costs incurred in excess of a specified benchmark. These costs are eligible for recovery in a future filing after such costs are approved by the RRC.
v3.26.1
Segment Information
 9 Months Ended
Jun. 30, 2026
Segment Reporting [Abstract]  
Segment Information Segment Information
We manage and review our consolidated operations through the following reportable segments:

•The distribution segment is comprised of our regulated natural gas distribution and related sales operations in eight states.
•The pipeline and storage segment is comprised primarily of the regulated pipeline and storage operations of our Atmos Pipeline-Texas division and our natural gas transmission operations in Louisiana.
The accounting policies of the segments are the same as those described in the summary of significant accounting policies found in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025.
Income statement information and capital expenditures for the three and nine months ended June 30, 2026 and 2025 by segment are presented in the following tables:
Three Months Ended June 30, 2026
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$773,909 $105,150 $879,059 
Intersegment revenues749 227,903 228,652 
Total operating revenues774,658 333,053 1,107,711 
Operation and maintenance expense169,195 55,474 224,669 
Depreciation and amortization expense (2)
148,349 53,172 201,521 
Interest charges (2)
12,870 20,274 33,144 
Income tax expense (2)
15,558 45,036 60,594 
Other segment items (1)
339,301 5,793 345,094 
Net income (2)
$89,385 $153,304 $242,689 
Capital expenditures (2)
$858,790 $180,556 $1,039,346 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$1,107,711 
Elimination of intersegment revenues(228,652)
Consolidated total operating revenues$879,059 

Three Months Ended June 30, 2025
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$766,380 $72,394 $838,774 
Intersegment revenues752 199,994 200,746 
Total operating revenues767,132 272,388 1,039,520 
Operation and maintenance expense165,979 55,497 221,476 
Depreciation and amortization expense (2)
137,106 48,680 185,786 
Interest charges (2)
22,271 19,266 41,537 
Income tax expense (2)
9,731 34,470 44,201 
Other segment items (1)
361,564 (1,473)360,091 
Net income (2)
$70,481 $115,948 $186,429 
Capital expenditures (2)
$669,452 $197,478 $866,930 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$1,039,520 
Elimination of intersegment revenues(200,746)
Consolidated total operating revenues$838,774 
Nine Months Ended June 30, 2026
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$3,908,869 $275,177 $4,184,046 
Intersegment revenues2,295 633,798 636,093 
Total operating revenues3,911,164 908,975 4,820,139 
Operation and maintenance expense490,481 141,120 631,601 
Depreciation and amortization expense (2)
441,088 150,765 591,853 
Interest charges (2)
66,445 48,843 115,288 
Income tax expense (2)
186,414 126,488 312,902 
Other segment items (1)
1,930,813 10,130 1,940,943 
Net income (2)
$795,923 $431,629 $1,227,552 
Capital expenditures (2)
$2,380,444 $695,837 $3,076,281 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,820,139 
Elimination of intersegment revenues(636,093)
Consolidated total operating revenues$4,184,046 

Nine Months Ended June 30, 2025
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$3,756,691 $208,584 $3,965,275 
Intersegment revenues2,304 578,193 580,497 
Total operating revenues3,758,995 786,777 4,545,772 
Operation and maintenance expense479,972 160,238 640,210 
Depreciation and amortization expense (2)
405,279 143,790 549,069 
Interest charges (2)
86,607 57,869 144,476 
Income tax expense (2)
147,833 93,220 241,053 
Other segment items (1)
1,947,967 (866)1,947,101 
Net income (2)
$691,337 $332,526 $1,023,863 
Capital expenditures (2)
$1,889,954 $707,833 $2,597,787 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,545,772 
Elimination of intersegment revenues(580,497)
Consolidated total operating revenues$3,965,275 
(1)Other segment items consist of purchased gas cost, bad debt expense, taxes other than income taxes, the equity component of AFUDC, community support spending, and other segment income or expense deemed insignificant which are used to reach net income, our measurement of segment profit or loss.
(2)The totals of reportable segments for these items agree to consolidated totals.
Balance sheet information at June 30, 2026 and September 30, 2025 by segment is presented in the following tables:
June 30, 2026
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Net property, plant and equipment (1)
$20,878,848 $7,136,762 $28,015,610 
Total assets$30,490,005 $7,539,119 $38,029,124 
Reconciliation to consolidated assets:
Total assets of reportable segments$38,029,124 
Elimination of intersegment assets(6,443,585)
Consolidated total assets$31,585,539 
September 30, 2025
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Net property, plant and equipment (1)
$18,765,128 $6,527,862 $25,292,990 
Total assets$27,296,805 $6,896,646 $34,193,451 
Reconciliation to consolidated assets:
Total assets of reportable segments$34,193,451 
Elimination of intersegment assets(5,943,929)
Consolidated total assets$28,249,522 
(1)The total of reportable segments for this item reconciles to consolidated total.
v3.26.1
Earnings Per Share
 9 Months Ended
Jun. 30, 2026
Earnings Per Share [Abstract]  
Earnings Per Share Earnings Per Share
We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock. Additionally, the weighted average shares outstanding for diluted EPS includes the incremental effects of the forward sale agreements, discussed in Note 8 to the condensed consolidated financial statements, when the impact is dilutive.
Basic and diluted earnings per share for the three and nine months ended June 30, 2026 and 2025 are calculated as follows:
Three Months Ended June 30Nine Months Ended June 30
2026202520262025
(In thousands, except per share amounts)
Basic Earnings Per Share
Net income$242,689 $186,429 $1,227,552 $1,023,863 
Less: Income allocated to participating securities
76 87 370 422 
Income available to common shareholders
$242,613 $186,342 $1,227,182 $1,023,441 
Basic weighted average shares outstanding
168,345 159,285 165,845 158,245 
Net income per share — Basic
$1.44 $1.17 $7.40 $6.47 
Diluted Earnings Per Share
Income available to common shareholders$242,613 $186,342 $1,227,182 $1,023,441 
Effect of dilutive shares
— — — — 
Income available to common shareholders
$242,613 $186,342 $1,227,182 $1,023,441 
Basic weighted average shares outstanding
168,345 159,285 165,845 158,245 
Dilutive shares1,029 1,886 1,507 1,553 
Diluted weighted average shares outstanding
169,374 161,171 167,352 159,798 
Net income per share — Diluted$1.43 $1.16 $7.33 $6.40 
v3.26.1
Revenue and Accounts Receivable
 9 Months Ended
Jun. 30, 2026
Revenue from Contract with Customer [Abstract]  
Revenue and Accounts Receivable Revenue and Accounts Receivable
Revenue
Our revenue recognition policy is fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. 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, 2026 and 2025.
Three Months Ended June 30, 2026Three Months Ended June 30, 2025
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$462,720 $— $473,478 $— 
Commercial214,797 — 213,377 — 
Industrial26,464 — 27,369 — 
Public authority and other5,757 — 8,920 — 
Total gas sales revenues709,738 — 723,144 — 
Transportation revenues39,498 395,186 35,908 284,103 
Miscellaneous revenues3,011 11,077 3,326 4,656 
Revenues from contracts with customers752,247 406,263 762,378 288,759 
Alternative revenue program revenues18,588 (73,210)1,438 (16,371)
Other revenues3,823 — 3,316 — 
Total operating revenues$774,658 $333,053 $767,132 $272,388 
Nine Months Ended June 30, 2026Nine Months Ended June 30, 2025
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$2,462,924 $— $2,475,219 $— 
Commercial999,363 — 959,539 — 
Industrial103,804 — 92,575 — 
Public authority and other31,292 — 45,722 — 
Total gas sales revenues3,597,383 — 3,573,055 — 
Transportation revenues125,339 1,031,369 115,987 816,646 
Miscellaneous revenues9,310 17,058 10,570 11,579 
Revenues from contracts with customers3,732,032 1,048,427 3,699,612 828,225 
Alternative revenue program revenues167,599 (139,452)48,657 (41,448)
Other revenues11,533 — 10,726 — 
Total operating revenues$3,911,164 $908,975 $3,758,995 $786,777 
We have alternative revenue programs in each of our segments. In our distribution segment, we have weather-normalization adjustment mechanisms that serve to mitigate the effects of weather on our revenue. In our pipeline and storage segment, APT has a regulatory mechanism that requires that we share with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a revenue benchmark established by the RRC. Other revenues includes AEK revenues (see Note 9 to the condensed consolidated financial statements) and other miscellaneous revenues.
Accounts receivable and allowance for uncollectible accounts
Accounts receivable arise from natural gas sales to residential, commercial, industrial, public authority, and other customers. Our accounts receivable balance includes unbilled amounts which represent a customer’s consumption of gas from the date of the last cycle billing through the last day of the month. Our policy related to the accounting for our accounts receivable and allowance for uncollectible accounts is fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. During the nine months ended June 30, 2026, there were no material changes to this policy. Rollforwards of our allowance for uncollectible accounts for the three and nine months ended June 30, 2026 and 2025 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 89 percent of our customers as we have the ability to collect these gas costs through our gas cost recovery mechanisms in most of our jurisdictions.
Three Months Ended June 30, 2026
(In thousands)
Beginning balance, March 31, 2026$55,344 
Current period provisions513 
Write-offs charged against allowance(4,813)
Recoveries of amounts previously written off303 
Ending balance, June 30, 2026
$51,347 
Three Months Ended June 30, 2025
(In thousands)
Beginning balance, March 31, 2025$49,341 
Current period provisions1,771 
Write-offs charged against allowance(5,054)
Recoveries of amounts previously written off302 
Ending balance, June 30, 2025
$46,360 
Nine Months Ended June 30, 2026
(In thousands)
Beginning balance, September 30, 2025
$45,259 
Current period provisions21,998 
Write-offs charged against allowance(17,679)
Recoveries of amounts previously written off1,769 
Ending balance, June 30, 2026
$51,347 
Nine Months Ended June 30, 2025
(In thousands)
Beginning balance, September 30, 2024
$37,056 
Current period provisions24,786 
Write-offs charged against allowance(17,263)
Recoveries of amounts previously written off1,781 
Ending balance, June 30, 2025
$46,360 
v3.26.1
Debt
 9 Months Ended
Jun. 30, 2026
Debt Disclosure [Abstract]  
Debt Debt
The nature and terms of our debt instruments and credit facilities are described in detail in Note 8 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. Other than as described below, there were no material changes in the terms of our debt instruments during the nine months ended June 30, 2026.
Long-term debt at June 30, 2026 and September 30, 2025 consisted of the following:
June 30, 2026September 30, 2025
(In thousands)
Unsecured 3.00% Senior Notes, due June 2027
$500,000 $500,000 
Unsecured 2.625% Senior Notes, due September 2029
500,000 500,000 
Unsecured 1.50% Senior Notes, due January 2031
600,000 600,000 
Unsecured 4.75% Senior Notes, due January 2032
700,000 — 
Unsecured 5.45% Senior Notes, due October 2032
300,000 300,000 
Unsecured 5.90% Senior Notes, due November 2033
725,000 725,000 
Unsecured 5.95% Senior Notes, due October 2034
200,000 200,000 
Unsecured 5.20% Senior Notes, due August 2035
500,000 500,000 
Unsecured 5.50% Senior Notes, due June 2041
400,000 400,000 
Unsecured 4.15% Senior Notes, due January 2043
500,000 500,000 
Unsecured 4.125% Senior Notes, due October 2044
750,000 750,000 
Unsecured 4.30% Senior Notes, due October 2048
600,000 600,000 
Unsecured 4.125% Senior Notes, due March 2049
450,000 450,000 
Unsecured 3.375% Senior Notes, due September 2049
500,000 500,000 
Unsecured 2.85% Senior Notes, due February 2052
600,000 600,000 
Unsecured 5.75% Senior Notes, due October 2052
500,000 500,000 
Unsecured 6.20% Senior Notes, due November 2053
500,000 500,000 
Unsecured 5.00% Senior Notes, due December 2054
650,000 650,000 
Unsecured 5.45% Senior Notes, due January 2056
600,000 — 
Medium-term note Series A, 1995-1, 6.67%, due December 2025
— 10,000 
Unsecured 6.75% Debentures, due July 2028
150,000 150,000 
Finance lease obligations101,185 47,234 
Total long-term debt10,326,185 8,982,234 
Less:
Original issue (premium) discount on unsecured senior notes and debentures3,135 (1,332)
Debt issuance cost71,792 64,622 
Current maturities of long-term debt502,542 11,775 
Total long-term debt, net$9,748,716 $8,907,169 
On October 1, 2025, we completed a public offering of $600 million of 5.45% senior notes due January 2056, with an effective interest rate of 4.85%, after giving effect to the offering costs and settlement of our interest rate swaps. The net proceeds from the offering, after the underwriting discount and offering expenses, of $590.0 million were used for general corporate purposes.
On June 18, 2026, we completed a public offering of $700 million of 4.75% senior notes due January 2032 with an effective interest rate of 4.92%, after giving effect to the offering costs. The net proceeds from the offering, after the underwriting discount and offering expenses, of $694.0 million were used for general corporate purposes.
Short-term debt
We utilize short-term debt to provide cost-effective, short-term financing until it can be replaced with a balance of long-term debt and equity financing that achieves the Company’s desired capital structure. Our short-term borrowing requirements are driven primarily by construction work in progress and the seasonal nature of the natural gas business.
Our short-term borrowing requirements are satisfied through a combination of a $1.5 billion commercial paper program and four committed revolving credit facilities with third-party lenders that provide $3.1 billion of total working capital funding.
The primary source of our funding is our commercial paper program, which is supported by a five-year unsecured $1.5 billion credit facility. On March 27, 2026, we elected to extend the maturity date from March 28, 2030 to March 28, 2031. This facility bears interest at a base rate or at a Term SOFR-based rate for the applicable interest period, plus a margin ranging from zero percent to 0.25 percent for base rate advances or a margin ranging from 0.75 percent to 1.25 percent for Term SOFR-based advances, based on the Company’s credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the total committed loan to $1.75 billion. At June 30, 2026 and September 30, 2025, there were no amounts outstanding under our commercial paper program.
We also have a $1.5 billion three-year senior unsecured credit facility that is used to provide additional working capital funding. On March 27, 2026, we elected to extend the maturity date from March 28, 2028 to March 28, 2029. This facility bears interest at a base rate or at a Term SOFR-based rate for the applicable interest period, plus a margin ranging from zero percent to 0.25 percent for base rate advances or a margin ranging from 0.75 percent to 1.25 percent for Term SOFR-based advances, based on the Company's credit ratings. Additionally, the facility contains a $250 million accordion feature, which provides the opportunity to increase the total committed loan to $1.75 billion. At June 30, 2026 and September 30, 2025, there were no borrowings outstanding under this facility.
Additionally, we have a $50 million 364-day unsecured facility, which was renewed April 1, 2026 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of June 30, 2026 and September 30, 2025.
Finally, we have a $50 million 364-day unsecured revolving credit facility, which was renewed March 31, 2026 and is used to issue letters of credit and to provide working capital funding. At June 30, 2026, there were no borrowings outstanding under this facility; however, outstanding letters of credit reduced the total amount available to us to $44.4 million.
Debt covenants
The availability of funds under these credit facilities is subject to conditions specified in the respective credit agreements, all of which we currently satisfy. These conditions include our compliance with financial covenants and the continued accuracy of representations and warranties contained in these agreements. We are required by the financial covenants in each of these facilities to maintain, at the end of each fiscal quarter, a ratio of total-debt-to-total-capitalization of no greater than 70 percent. At June 30, 2026, our total-debt-to-total-capitalization ratio, as defined in the agreements, was 41 percent. In addition, both the interest margin and the fee that we pay on unused amounts under certain of these facilities are subject to adjustment depending upon our credit ratings.
These credit facilities and our public indentures contain usual and customary covenants for our business, including covenants substantially limiting liens, substantial asset sales, and mergers. Additionally, our public debt indentures relating to our senior notes and debentures, as well as certain of our revolving credit agreements, each contain a default provision that is triggered if outstanding indebtedness arising out of any other credit agreements in amounts ranging from in excess of $15 million to in excess of $100 million becomes due by acceleration or if not paid at maturity. We were in compliance with all of our debt covenants as of June 30, 2026. 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.
v3.26.1
Shareholders' Equity
 9 Months Ended
Jun. 30, 2026
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, 2026 and 2025.
Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
(In thousands, except share and per share data)
Balance, September 30, 2025
161,568,384 $808 $8,221,455 $475,015 $4,861,612 $13,558,890 
Net income— — — — 402,964 402,964 
Other comprehensive loss— — — (4,805)— (4,805)
Cash dividends ($1.00 per share)
— — — — (160,407)(160,407)
Common stock issued:
Public and other stock offerings3,709,647 18 474,625 — — 474,643 
Stock-based compensation plans156,446 1 11,606 — — 11,607 
Balance, December 31, 2025165,434,477 827 8,707,686 470,210 5,104,169 14,282,892 
Net income— — — — 581,899 581,899 
Other comprehensive loss— — — (4,938)— (4,938)
Cash dividends ($1.00 per share)
— — — — (168,760)(168,760)
Common stock issued:
Public and other stock offerings1,445,607 7 205,376 — — 205,383 
Stock-based compensation plans38,226 1 12,173 — — 12,174 
Balance, March 31, 2026166,918,310 835 8,925,235 465,272 5,517,308 14,908,650 
Net income— — — — 242,689 242,689 
Other comprehensive loss— — — (4,865)— (4,865)
Cash dividends ($1.00 per share)
— — — — (169,142)(169,142)
Common stock issued:
Public and other stock offerings2,001,479 10 274,109 — — 274,119 
Stock-based compensation plans66,460 — 6,607 — — 6,607 
Balance, June 30, 2026168,986,249 $845 $9,205,951 $460,407 $5,590,855 $15,258,058 
Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
(In thousands, except share and per share data)
Balance, September 30, 2024
155,258,845 $776 $7,474,559 $465,715 $4,216,619 $12,157,669 
Net income— — — — 351,858 351,858 
Other comprehensive income— — — 16,423 — 16,423 
Cash dividends ($0.87 per share)
— — — — (135,453)(135,453)
Common stock issued:
Public and other stock offerings3,329,358 17 383,520 — — 383,537 
Stock-based compensation plans137,862 1 6,446 — — 6,447 
Balance, December 31, 2024158,726,065 794 7,864,525 482,138 4,433,024 12,780,481 
Net income— — — — 485,576 485,576 
Other comprehensive loss— — — (5,587)— (5,587)
Cash dividends ($0.87 per share)
— — — — (138,416)(138,416)
Common stock issued:
Public and other stock offerings26,367 — 3,841 — — 3,841 
Stock-based compensation plans82,691 — 12,070 — — 12,070 
Balance, March 31, 2025158,835,123 794 7,880,436 476,551 4,780,184 13,137,965 
Net income— — — — 186,429 186,429 
Other comprehensive income— — — 1,409 — 1,409 
Cash dividends ($0.87 per share)
— — — — (138,443)(138,443)
Common stock issued:
Public and other stock offerings1,630,943 8 192,749 — — 192,757 
Stock-based compensation plans54,945 1 5,720 — — 5,721 
Balance, June 30, 2025160,521,011 $803 $8,078,905 $477,960 $4,828,170 $13,385,838 
Shelf Registration, At-the-Market Equity Sales Program and Equity Issuances
We have a shelf registration statement on file with the Securities and Exchange Commission (SEC) that allows us to issue up to $8.0 billion in common stock and/or debt securities, which expires December 3, 2027. At June 30, 2026, $4.5 billion of securities were available for issuance under this shelf registration statement.
We also have an at-the-market (ATM) equity sales program under which we may issue and sell shares of our common stock up to an aggregate offering price of $1.7 billion through December 3, 2027 (including shares of common stock that may be sold pursuant to forward sale agreements entered into concurrently with the ATM equity sales program).
During the nine months ended June 30, 2026, we settled forward sale agreements with respect to 7,084,863 shares that had been borrowed and sold by various forward sellers under the ATM program for net proceeds of $941.7 million. As of June 30, 2026, $506.5 million of equity was available for issuance under our existing ATM program. Additionally, we had $936.8 million in available proceeds from outstanding forward sale agreements, as detailed below.
MaturityShares AvailableNet Proceeds Available
(In thousands)		Forward Price
December 31, 20262,377,352 $334,047 $140.51 
March 31, 20271,873,444 287,072 $153.23 
June 30, 20271,878,143 315,722 $168.10 
Total6,128,939 $936,841 $152.86 
Accumulated Other Comprehensive Income (Loss)
We record deferred gains (losses) in AOCI related to available-for-sale debt securities and interest rate agreement cash flow hedges. Deferred gains (losses) for our available-for-sale debt securities are recognized in earnings upon settlement, while
deferred gains (losses) related to our interest rate agreement cash flow hedges are recognized in earnings on a straight-line basis over the life of the related financing. The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss).
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
(In thousands)
September 30, 2025$209 $474,806 $475,015 
Other comprehensive income (loss) before reclassifications(242)— (242)
Amounts reclassified from accumulated other comprehensive income— (14,366)(14,366)
Net current-period other comprehensive income (loss)(242)(14,366)(14,608)
June 30, 2026$(33)$460,440 $460,407 
 
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
(In thousands)
September 30, 2024$213 $465,502 $465,715 
Other comprehensive income (loss) before reclassifications(34)23,400 23,366 
Amounts reclassified from accumulated other comprehensive income— (11,121)(11,121)
Net current-period other comprehensive income (loss)(34)12,279 12,245 
June 30, 2025$179 $477,781 $477,960 
v3.26.1
Securitization
 9 Months Ended
Jun. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Securitization Securitization
Kansas
Atmos Energy Kansas Securitization I, LLC (AEK), a special-purpose entity wholly owned by Atmos Energy, was formed for the purpose of issuing securitized bonds to recover extraordinary costs incurred during Winter Storm Uri in February 2021. In June 2023, AEK completed a public offering of $95 million of Securitized Utility Tariff Bonds. AEK's assets cannot be used to settle Atmos Energy's obligations, and the holders of the Securitized Utility Tariff Bonds have no recourse against Atmos Energy.
As described in Note 10 of our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, AEK is considered to be a variable interest entity. As a result, AEK is included in the condensed consolidated financial statements of Atmos Energy.
The following table summarizes the impact of AEK on our condensed consolidated balance sheets, for the periods indicated:
June 30, 2026September 30, 2025
(In thousands)
Restricted cash and cash equivalents$4,856 $1,116 
Other current assets$9 $1 
Securitized intangible asset, net$68,026 $75,127 
Accrued interest$1,251 $331 
Current maturities of securitized long-term debt$8,858 $8,767 
Securitized long-term debt$63,751 $68,236 
The following table summarizes the impact of AEK on our condensed consolidated statements of comprehensive income, for the periods indicated:
Three Months Ended June 30Nine Months Ended June 30
2026202520262025
(In thousands)
Operating revenues$3,379 $2,855 $10,183 $9,199 
Operation and maintenance expense(52)(189)(238)(466)
Amortization expense(2,407)(1,646)(7,101)(5,599)
Interest expense, net(920)(1,020)(2,844)(3,134)
Income before income taxes$— $— $— $— 
The securitized long-term debt is recorded at carrying value. The fair value of the securitized long-term debt is determined using third party market value quotations, which are considered Level 2 fair value measurements for debt instruments where fair value is determined using the most recent available quoted market price. The carrying value and fair value of the securitized long-term debt as of June 30, 2026 was $72.6 million and $73.2 million, and as of September 30, 2025 was $77.0 million and $78.8 million.
Texas
In March 2023, the Texas Natural Gas Securitization Finance Corporation (the Finance Corporation), with the authority of the Texas Public Finance Authority (TPFA), issued $3.5 billion in customer rate relief bonds with varying scheduled final maturities from 12 to 18 years. The bonds are obligations of the Finance Corporation, payable from the customer rate relief charges and other bond collateral, and are not an obligation of Atmos Energy. We began collecting the customer rate relief charges on October 1, 2023, and any such property collected is solely owned by the Finance Corporation and not available to pay creditors of Atmos Energy.
v3.26.1
Interim Pension and Other Postretirement Benefit Plan Information
 9 Months Ended
Jun. 30, 2026
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, 2026 and 2025 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 income.
Three Months Ended June 30
Pension BenefitsOther Benefits
2026202520262025
(In thousands)
Components of net periodic pension cost:
Service cost$2,580 $2,838 $2,018 $2,033 
Interest cost (1)
6,924 6,663 3,634 3,365 
Expected return on assets (1)
(7,949)(7,655)(4,069)(3,831)
Amortization of prior service cost (credit) (1)
— — (2,880)(3,260)
Amortization of actuarial (gain) loss (1)
(51)256 (2,414)(2,429)
Net periodic pension cost$1,504 $2,102 $(3,711)$(4,122)
Nine Months Ended June 30
Pension BenefitsOther Benefits
2026202520262025
(In thousands)
Components of net periodic pension cost:
Service cost$7,740 $8,512 $6,052 $6,099 
Interest cost (1)
20,774 19,989 10,904 10,096 
Expected return on assets (1)
(23,847)(22,964)(12,209)(11,494)
Amortization of prior service cost (credit) (1)
— — (8,639)(9,780)
Amortization of actuarial (gain) loss (1)
(153)767 (7,244)(7,287)
Net periodic pension cost$4,514 $6,304 $(11,136)$(12,366)
(1)    The components of net periodic cost other than the service cost component are included in the line item other non-operating income in the condensed consolidated statements of comprehensive income or are capitalized on the condensed consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025.
v3.26.1
Commitments and Contingencies
 9 Months Ended
Jun. 30, 2026
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies Commitments and Contingencies
Litigation and Environmental Matters
In the normal course of business, we are subject to various legal and regulatory proceedings. For such matters, we record liabilities when they are considered probable and estimable, based on currently available facts, our historical experience and our estimates of the ultimate outcome or resolution of the liability in the future. While the outcome of these proceedings is uncertain and a loss in excess of the amount we have accrued is possible though not reasonably estimable, it is the opinion of management that any amounts exceeding the accruals will not have a material adverse impact on our financial position, results of operations or cash flows.
The National Transportation Safety Board (NTSB) issued a Preliminary Report on February 14, 2024 relating to its investigation of two incidents that occurred in Jackson, Mississippi on January 24 and 27, 2024 that resulted in one fatality. On March 26, 2026, the NTSB issued its final report and recommendations.
The NTSB issued a Preliminary Report on December 30, 2024 relating to its investigation of an incident that occurred in Avondale, Louisiana on December 2, 2024 that resulted in one fatality. On May 27, 2026, the NTSB issued its final report.
The NTSB issued a Preliminary report on July 1, 2026 relating to its investigation of an incident that occurred in Dallas, Texas on May 28, 2026 that resulted in three fatalities. Atmos Energy is working closely with the NTSB and other state and federal regulators to help determinate causal factors.
We are a party to various litigation and environmental-related matters or claims that have arisen in the ordinary course of our business. While the results of such litigation and response actions to such environmental-related matters or claims cannot be predicted with certainty, we continue to believe the final outcome of such litigation and matters or claims will not have a material adverse effect on our financial condition, results of operations, or cash flows.
Purchase Commitments
Our distribution divisions maintain supply contracts with several vendors that generally cover a period of up to one year. Commitments for estimated base gas volumes are established under these contracts on a monthly basis at contractually negotiated prices. Commitments for incremental daily purchases are made as necessary during the month in accordance with the terms of the individual contract.
Our Mid-Tex Division also maintains a limited number of long-term supply contracts to ensure a reliable source of gas for our customers in its service area, which obligate it to purchase specified volumes at prices under contracts indexed to natural gas hubs or fixed price contracts. These purchase commitment contracts are detailed in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. At June 30, 2026, we were committed to purchase 69.2 Bcf within one year and 52.4 Bcf within two to three years under indexed contracts. At June 30, 2026, we were committed to purchase 7.9 Bcf within one year under our fixed price contracts with a weighted average price of $3.03 per Mcf.
Rate Regulatory Proceedings
As of June 30, 2026, routine rate regulatory proceedings were in progress in several of our service areas, which are discussed in further detail below in Management’s Discussion and Analysis — Recent Ratemaking Developments. Except for these proceedings, there were no material changes to rate regulatory proceedings for the nine months ended June 30, 2026.
v3.26.1
Income Taxes
 9 Months Ended
Jun. 30, 2026
Income Tax Disclosure [Abstract]  
Income Taxes Income Taxes
Income Tax Expense
Our interim effective tax rates reflect the estimated annual effective tax rates for the fiscal years ended September 30, 2026 and 2025, adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended June 30, 2026 and 2025 were 20.0% and 19.2% and for the nine months ended June 30, 2026 and 2025 were 20.3% and 19.1%. These effective tax rates differ from the federal statutory tax rate of 21% primarily due to the amortization of excess deferred federal income tax liabilities, tax credits, state income taxes, and other permanent book-to-tax differences. These adjustments have a relative impact on the effective tax rate proportionally to pretax income or loss.
Regulatory Excess Deferred Taxes
Regulatory excess net deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of the Tax Cuts and Jobs Act of 2017 (the TCJA), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. Currently, the regulatory excess net deferred tax liability of $86.0 million is being returned over various periods. Of this amount, $38.6 million is being returned to customers over 36 - 60 months. An additional $46.4 million is being returned to customers on a provisional basis over 15 - 46 years until our regulators establish the final refund periods. The refund of the remaining $1.0 million will be addressed in future rate proceedings.
As of June 30, 2026 and September 30, 2025, $34.4 million and $72.8 million is recorded in other current liabilities.
v3.26.1
Financial Instruments
 9 Months Ended
Jun. 30, 2026
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Financial Instruments Financial Instruments
We currently use financial instruments to mitigate commodity price risk and interest rate risk. The objectives and strategies for using financial instruments and the related accounting for these financial instruments are fully described in Notes 2 and 16 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. During the nine months ended June 30, 2026, 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 2025-2026 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 23.8 Bcf of the winter flowing gas requirements. We have not designated these financial instruments as hedges for accounting purposes.
Interest Rate Risk Management Activities
We manage interest rate risk by periodically entering into financial instruments to effectively fix the Treasury yield component of the interest cost associated with anticipated financings.
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, 2026, 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, 2026, we had 18,662 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, 2026 and September 30, 2025. The gross amounts of recognized assets and liabilities are netted within our condensed consolidated balance sheets to the extent that we have netting arrangements with our counterparties. However, as of June 30, 2026 and September 30, 2025, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
June 30, 2026
Balance Sheet LocationAssetsLiabilities
 (In thousands)
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		$3,824 $(2,822)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		3,026 — 
Total6,850 (2,822)
Gross / Net Financial Instruments$6,850 $(2,822)
 
September 30, 2025
Balance Sheet LocationAssetsLiabilities
 (In thousands)
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		$5,303 $(6,339)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		4,594 (146)
Total9,897 (6,485)
Gross / Net Financial Instruments$9,897 $(6,485)
Impact of Financial Instruments on the Statement of Comprehensive Income
Cash Flow Hedges
As discussed above, our distribution segment has interest rate agreements, which we designated as cash flow hedges at the time the agreements were executed. The net (gain) loss on settled interest rate agreements reclassified from AOCI into interest charges on our condensed consolidated statements of comprehensive income for the three months ended June 30, 2026 and 2025 was $(6.1) million and $(5.1) million and for the nine months ended June 30, 2026 and 2025 was $(18.4) million and $(15.4) million.
The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and nine months ended June 30, 2026 and 2025.
Three Months Ended June 30Nine Months Ended June 30
2026202520262025
(In thousands)
Increase in fair value:
Interest rate agreements$— $5,359 $— $23,400 
Recognition of gains in earnings due to settlements:
Interest rate agreements(4,780)(3,981)(14,366)(11,121)
Total other comprehensive income (loss) from hedging, net of tax$(4,780)$1,378 $(14,366)$12,279 
Deferred gains (losses) recorded in AOCI associated with our interest rate agreements are recognized in earnings as they are amortized over the terms of the underlying debt instruments. As of June 30, 2026, we had $460.4 million of net realized gains in AOCI associated with our interest rate agreements. The following amounts, net of deferred taxes, represent the expected recognition in earnings of the deferred net gains recorded in AOCI associated with our interest rate agreements, based upon the fair values of these agreements at the date of settlement. The remaining amortization periods for these settled amounts
extend through fiscal 2056. 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$19,118 
Thereafter441,323 
Total$460,441 

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.
v3.26.1
Fair Value Measurements
 9 Months Ended
Jun. 30, 2026
Fair Value Disclosures [Abstract]  
Fair Value Measurements Fair Value Measurements
We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, restricted cash and cash equivalents, accounts receivable, accounts payable, and short-term debt at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. During the nine months ended June 30, 2026, there were no changes in these methods.
Fair value measurements also apply to the valuation of our pension and postretirement plan assets. Current accounting guidance requires employers to annually disclose information about fair value measurements of the assets of a defined benefit pension or other postretirement plan. The fair value of these assets is presented in Note 11 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025.
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, 2026 and September 30, 2025. 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, 2026
(In thousands)
Assets:
Financial instruments$— $6,850 $— $— $6,850 
Debt and equity securities
Registered investment companies25,487 — — — 25,487 
Bond mutual funds43,068 — — — 43,068 
Bonds (2)
— 48,660 — — 48,660 
Money market funds— 3,125 — — 3,125 
Total debt and equity securities68,555 51,785 — — 120,340 
Total assets$68,555 $58,635 $— $— $127,190 
Liabilities:
Financial instruments$— $2,822 $— $— $2,822 

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, 2025
(In thousands)
Assets:
Financial instruments$— $9,897 $— $— $9,897 
Debt and equity securities
Registered investment companies26,463 — — — 26,463 
Bond mutual funds42,106 — — — 42,106 
Bonds (2)
— 42,754 — — 42,754 
Money market funds— 3,615 — — 3,615 
Total debt and equity securities68,569 46,369 — — 114,938 
Total assets$68,569 $56,266 $— $— $124,835 
Liabilities:
Financial instruments$— $6,485 $— $— $6,485 
 
(1)Our Level 2 measurements consist of over-the-counter options and swaps, which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds, which are valued based on the most recent available quoted market prices and money market funds that are valued at cost.
(2)Our investments in bonds are considered available-for-sale debt securities in accordance with current accounting guidance.
Debt and equity securities are comprised of our available-for-sale debt securities and our equity securities. As described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025, we evaluate the performance of our available-for-sale debt securities on an investment by investment basis for impairment, taking into consideration the investment’s purpose, volatility, current returns, and any intent to sell the security. As of June 30, 2026, no allowance for credit losses was recorded for our available-for-sale debt securities. At June 30, 2026 and September 30, 2025, the amortized cost of our available-for-sale debt securities was $48.7 million and $42.5 million. At June 30, 2026, we maintained investments in bonds that have contractual maturity dates ranging from July 2026 through June 2029.
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, 2026 and September 30, 2025:
June 30, 2026September 30, 2025
(In thousands)
Carrying Amount$10,225,000 $8,935,000 
Fair Value$9,379,797 $8,272,978 
v3.26.1
Concentration of Credit Risk
 9 Months Ended
Jun. 30, 2026
Risks and Uncertainties [Abstract]  
Concentration of Credit Risk Concentration of Credit Risk
Information regarding our concentration of credit risk is disclosed in Note 18 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. During the nine months ended June 30, 2026, there were no material changes in our concentration of credit risk.
v3.26.1
Insider Trading Arrangements
 3 Months Ended
Jun. 30, 2026
Trading Arrangements, by Individual  
Rule 10b5-1 Arrangement Adopted false
Non-Rule 10b5-1 Arrangement Adopted false
Rule 10b5-1 Arrangement Terminated false
Non-Rule 10b5-1 Arrangement Terminated false
v3.26.1
Summary of Significant Accounting Policies (Policies)
 9 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]  
Basis of presentation
Basis of presentation
These consolidated interim-period financial statements have been prepared in accordance with accounting principles generally accepted in the United States on the same basis as those used for the Company’s audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. 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, 2025. Because of seasonal and other factors, the results of operations for the nine-month period ended June 30, 2026 are not indicative of our results of operations for the full 2026 fiscal year, which ends September 30, 2026.
Goodwill impairment
During the second quarter of fiscal 2026, we completed our annual goodwill impairment assessment using a qualitative assessment, as permitted under U.S. GAAP. We test for goodwill impairment at the reporting unit level on an annual basis and between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of the reporting unit. Based on the assessment performed, we determined that our goodwill was not impaired.
Recently issued accounting pronouncements
Recently issued accounting pronouncements
In November 2024, the FASB issued guidance that will require more detailed information about the types of expenses in commonly presented expense captions. The amendment is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. This amendment will be effective for our Form 10-K for fiscal 2028 and our Form 10-Q for the first quarter of fiscal 2029. We are currently evaluating the impact this may have on our financial statement disclosures.
In September 2025, the FASB issued guidance which provides qualitative updates to the determination of capitalizing internal-use software costs by expanding the scope to allow for various software development methods. The amendment is effective for fiscal years beginning after December 15, 2027. Early adoption is permitted, and the amendment may be applied prospectively, retrospectively, or with a modified transition approach. This amendment will be effective for our Form 10-K for fiscal 2029 and our Form 10-Q for the first quarter of fiscal 2029. We are currently evaluating the impact this may have on our financial statement disclosures.
Earnings per share We use the two-class method of computing earnings per share because we have participating securities in the form of non-vested restricted stock units with a nonforfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. Basic weighted average shares outstanding is calculated based upon the weighted average number of common shares outstanding during the periods presented. Also, this calculation includes fully vested stock awards that have not yet been issued as common stock.
Fair value measurements
We report certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). We record cash and cash equivalents, restricted cash and cash equivalents, accounts receivable, accounts payable, and short-term debt at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025. During the nine months ended June 30, 2026, there were no changes in these methods.
v3.26.1
Regulation (Tables)
 9 Months Ended
Jun. 30, 2026
Regulated Operations [Abstract]  
Schedule of Regulatory Assets
Regulatory assets and liabilities as of June 30, 2026 and September 30, 2025 included the following:
June 30,
2026		September 30,
2025
(In thousands)
Regulatory assets:
Pension and postretirement benefit costs$3,857 $262 
Infrastructure mechanisms (1)
425,281 314,047 
Winter Storm Uri incremental costs1,141 5,841 
Deferred gas costs156,975 140,626 
Regulatory excess deferred taxes (2)
48,718 49,793 
Recoverable loss on reacquired debt2,777 2,903 
Deferred pipeline record collection costs35,642 39,035 
System Safety and Integrity Riders (3)
48,801 43,625 
Other18,439 12,597 
$741,631 $608,729 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$134,694 $190,274 
Regulatory cost of removal obligation645,942 641,019 
Deferred gas costs6,844 6,879 
APT annual adjustment mechanism182,546 99,393 
Pension and postretirement benefit costs289,505 291,351 
Other34,542 40,732 
$1,294,073 $1,269,648 
(1)Texas, Louisiana, and Tennessee have authorized infrastructure mechanisms that mitigate regulatory lag and allow for the deferral of eligible incurred costs related to qualifying capital expenditures until new rates are implemented. The investment and deferred costs are required to be included in the Company's next rate filing (rate case or annual rate filing) for recovery through base rates.
(2)Regulatory excess deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of the Tax Cuts and Jobs Act of 2017 (the "TCJA"), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. See Note 12 to the condensed consolidated financial statements for further information.
(3)In our APT and West Texas Divisions and portions of our Mid-Tex Division, the RRC has approved the deferral of certain system safety and integrity costs incurred in excess of a specified benchmark. These costs are eligible for recovery in a future filing after such costs are approved by the RRC.
Schedule of Regulatory Liabilities
Regulatory assets and liabilities as of June 30, 2026 and September 30, 2025 included the following:
June 30,
2026		September 30,
2025
(In thousands)
Regulatory assets:
Pension and postretirement benefit costs$3,857 $262 
Infrastructure mechanisms (1)
425,281 314,047 
Winter Storm Uri incremental costs1,141 5,841 
Deferred gas costs156,975 140,626 
Regulatory excess deferred taxes (2)
48,718 49,793 
Recoverable loss on reacquired debt2,777 2,903 
Deferred pipeline record collection costs35,642 39,035 
System Safety and Integrity Riders (3)
48,801 43,625 
Other18,439 12,597 
$741,631 $608,729 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$134,694 $190,274 
Regulatory cost of removal obligation645,942 641,019 
Deferred gas costs6,844 6,879 
APT annual adjustment mechanism182,546 99,393 
Pension and postretirement benefit costs289,505 291,351 
Other34,542 40,732 
$1,294,073 $1,269,648 
(1)Texas, Louisiana, and Tennessee have authorized infrastructure mechanisms that mitigate regulatory lag and allow for the deferral of eligible incurred costs related to qualifying capital expenditures until new rates are implemented. The investment and deferred costs are required to be included in the Company's next rate filing (rate case or annual rate filing) for recovery through base rates.
(2)Regulatory excess deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of the Tax Cuts and Jobs Act of 2017 (the "TCJA"), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. See Note 12 to the condensed consolidated financial statements for further information.
(3)In our APT and West Texas Divisions and portions of our Mid-Tex Division, the RRC has approved the deferral of certain system safety and integrity costs incurred in excess of a specified benchmark. These costs are eligible for recovery in a future filing after such costs are approved by the RRC.
v3.26.1
Segment Information (Tables)
 9 Months Ended
Jun. 30, 2026
Segment Reporting [Abstract]  
Schedule of Segment Reporting
Income statement information and capital expenditures for the three and nine months ended June 30, 2026 and 2025 by segment are presented in the following tables:
Three Months Ended June 30, 2026
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$773,909 $105,150 $879,059 
Intersegment revenues749 227,903 228,652 
Total operating revenues774,658 333,053 1,107,711 
Operation and maintenance expense169,195 55,474 224,669 
Depreciation and amortization expense (2)
148,349 53,172 201,521 
Interest charges (2)
12,870 20,274 33,144 
Income tax expense (2)
15,558 45,036 60,594 
Other segment items (1)
339,301 5,793 345,094 
Net income (2)
$89,385 $153,304 $242,689 
Capital expenditures (2)
$858,790 $180,556 $1,039,346 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$1,107,711 
Elimination of intersegment revenues(228,652)
Consolidated total operating revenues$879,059 

Three Months Ended June 30, 2025
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$766,380 $72,394 $838,774 
Intersegment revenues752 199,994 200,746 
Total operating revenues767,132 272,388 1,039,520 
Operation and maintenance expense165,979 55,497 221,476 
Depreciation and amortization expense (2)
137,106 48,680 185,786 
Interest charges (2)
22,271 19,266 41,537 
Income tax expense (2)
9,731 34,470 44,201 
Other segment items (1)
361,564 (1,473)360,091 
Net income (2)
$70,481 $115,948 $186,429 
Capital expenditures (2)
$669,452 $197,478 $866,930 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$1,039,520 
Elimination of intersegment revenues(200,746)
Consolidated total operating revenues$838,774 
Nine Months Ended June 30, 2026
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$3,908,869 $275,177 $4,184,046 
Intersegment revenues2,295 633,798 636,093 
Total operating revenues3,911,164 908,975 4,820,139 
Operation and maintenance expense490,481 141,120 631,601 
Depreciation and amortization expense (2)
441,088 150,765 591,853 
Interest charges (2)
66,445 48,843 115,288 
Income tax expense (2)
186,414 126,488 312,902 
Other segment items (1)
1,930,813 10,130 1,940,943 
Net income (2)
$795,923 $431,629 $1,227,552 
Capital expenditures (2)
$2,380,444 $695,837 $3,076,281 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,820,139 
Elimination of intersegment revenues(636,093)
Consolidated total operating revenues$4,184,046 

Nine Months Ended June 30, 2025
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Operating revenues from external parties$3,756,691 $208,584 $3,965,275 
Intersegment revenues2,304 578,193 580,497 
Total operating revenues3,758,995 786,777 4,545,772 
Operation and maintenance expense479,972 160,238 640,210 
Depreciation and amortization expense (2)
405,279 143,790 549,069 
Interest charges (2)
86,607 57,869 144,476 
Income tax expense (2)
147,833 93,220 241,053 
Other segment items (1)
1,947,967 (866)1,947,101 
Net income (2)
$691,337 $332,526 $1,023,863 
Capital expenditures (2)
$1,889,954 $707,833 $2,597,787 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,545,772 
Elimination of intersegment revenues(580,497)
Consolidated total operating revenues$3,965,275 
(1)Other segment items consist of purchased gas cost, bad debt expense, taxes other than income taxes, the equity component of AFUDC, community support spending, and other segment income or expense deemed insignificant which are used to reach net income, our measurement of segment profit or loss.
(2)The totals of reportable segments for these items agree to consolidated totals.
Balance sheet information at June 30, 2026 and September 30, 2025 by segment is presented in the following tables:
June 30, 2026
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Net property, plant and equipment (1)
$20,878,848 $7,136,762 $28,015,610 
Total assets$30,490,005 $7,539,119 $38,029,124 
Reconciliation to consolidated assets:
Total assets of reportable segments$38,029,124 
Elimination of intersegment assets(6,443,585)
Consolidated total assets$31,585,539 
September 30, 2025
DistributionPipeline and StorageTotal of Reportable Segments
(In thousands)
Net property, plant and equipment (1)
$18,765,128 $6,527,862 $25,292,990 
Total assets$27,296,805 $6,896,646 $34,193,451 
Reconciliation to consolidated assets:
Total assets of reportable segments$34,193,451 
Elimination of intersegment assets(5,943,929)
Consolidated total assets$28,249,522 
(1)The total of reportable segments for this item reconciles to consolidated total.
v3.26.1
Earnings Per Share (Tables)
 9 Months Ended
Jun. 30, 2026
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, 2026 and 2025 are calculated as follows:
Three Months Ended June 30Nine Months Ended June 30
2026202520262025
(In thousands, except per share amounts)
Basic Earnings Per Share
Net income$242,689 $186,429 $1,227,552 $1,023,863 
Less: Income allocated to participating securities
76 87 370 422 
Income available to common shareholders
$242,613 $186,342 $1,227,182 $1,023,441 
Basic weighted average shares outstanding
168,345 159,285 165,845 158,245 
Net income per share — Basic
$1.44 $1.17 $7.40 $6.47 
Diluted Earnings Per Share
Income available to common shareholders$242,613 $186,342 $1,227,182 $1,023,441 
Effect of dilutive shares
— — — — 
Income available to common shareholders
$242,613 $186,342 $1,227,182 $1,023,441 
Basic weighted average shares outstanding
168,345 159,285 165,845 158,245 
Dilutive shares1,029 1,886 1,507 1,553 
Diluted weighted average shares outstanding
169,374 161,171 167,352 159,798 
Net income per share — Diluted$1.43 $1.16 $7.33 $6.40 
v3.26.1
Revenue and Accounts Receivable (Tables)
 9 Months Ended
Jun. 30, 2026
Revenue from Contract with Customer [Abstract]  
Schedule of Disaggregation of Revenue The following tables disaggregate our revenue from contracts with customers by customer type and segment and provide a reconciliation to total operating revenues, including intersegment revenues, for the three and nine months ended June 30, 2026 and 2025.
Three Months Ended June 30, 2026Three Months Ended June 30, 2025
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$462,720 $— $473,478 $— 
Commercial214,797 — 213,377 — 
Industrial26,464 — 27,369 — 
Public authority and other5,757 — 8,920 — 
Total gas sales revenues709,738 — 723,144 — 
Transportation revenues39,498 395,186 35,908 284,103 
Miscellaneous revenues3,011 11,077 3,326 4,656 
Revenues from contracts with customers752,247 406,263 762,378 288,759 
Alternative revenue program revenues18,588 (73,210)1,438 (16,371)
Other revenues3,823 — 3,316 — 
Total operating revenues$774,658 $333,053 $767,132 $272,388 
Nine Months Ended June 30, 2026Nine Months Ended June 30, 2025
DistributionPipeline and StorageDistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$2,462,924 $— $2,475,219 $— 
Commercial999,363 — 959,539 — 
Industrial103,804 — 92,575 — 
Public authority and other31,292 — 45,722 — 
Total gas sales revenues3,597,383 — 3,573,055 — 
Transportation revenues125,339 1,031,369 115,987 816,646 
Miscellaneous revenues9,310 17,058 10,570 11,579 
Revenues from contracts with customers3,732,032 1,048,427 3,699,612 828,225 
Alternative revenue program revenues167,599 (139,452)48,657 (41,448)
Other revenues11,533 — 10,726 — 
Total operating revenues$3,911,164 $908,975 $3,758,995 $786,777 
Schedule of Allowance for Credit Loss Activity Rollforwards of our allowance for uncollectible accounts for the three and nine months ended June 30, 2026 and 2025 are presented in the table below. The allowance excludes the gas cost portion of customers’ bills for approximately 89 percent of our customers as we have the ability to collect these gas costs through our gas cost recovery mechanisms in most of our jurisdictions.
Three Months Ended June 30, 2026
(In thousands)
Beginning balance, March 31, 2026$55,344 
Current period provisions513 
Write-offs charged against allowance(4,813)
Recoveries of amounts previously written off303 
Ending balance, June 30, 2026
$51,347 
Three Months Ended June 30, 2025
(In thousands)
Beginning balance, March 31, 2025$49,341 
Current period provisions1,771 
Write-offs charged against allowance(5,054)
Recoveries of amounts previously written off302 
Ending balance, June 30, 2025
$46,360 
Nine Months Ended June 30, 2026
(In thousands)
Beginning balance, September 30, 2025
$45,259 
Current period provisions21,998 
Write-offs charged against allowance(17,679)
Recoveries of amounts previously written off1,769 
Ending balance, June 30, 2026
$51,347 
Nine Months Ended June 30, 2025
(In thousands)
Beginning balance, September 30, 2024
$37,056 
Current period provisions24,786 
Write-offs charged against allowance(17,263)
Recoveries of amounts previously written off1,781 
Ending balance, June 30, 2025
$46,360 
v3.26.1
Debt (Tables)
 9 Months Ended
Jun. 30, 2026
Debt Disclosure [Abstract]  
Schedule of Long-term Debt Instruments
Long-term debt at June 30, 2026 and September 30, 2025 consisted of the following:
June 30, 2026September 30, 2025
(In thousands)
Unsecured 3.00% Senior Notes, due June 2027
$500,000 $500,000 
Unsecured 2.625% Senior Notes, due September 2029
500,000 500,000 
Unsecured 1.50% Senior Notes, due January 2031
600,000 600,000 
Unsecured 4.75% Senior Notes, due January 2032
700,000 — 
Unsecured 5.45% Senior Notes, due October 2032
300,000 300,000 
Unsecured 5.90% Senior Notes, due November 2033
725,000 725,000 
Unsecured 5.95% Senior Notes, due October 2034
200,000 200,000 
Unsecured 5.20% Senior Notes, due August 2035
500,000 500,000 
Unsecured 5.50% Senior Notes, due June 2041
400,000 400,000 
Unsecured 4.15% Senior Notes, due January 2043
500,000 500,000 
Unsecured 4.125% Senior Notes, due October 2044
750,000 750,000 
Unsecured 4.30% Senior Notes, due October 2048
600,000 600,000 
Unsecured 4.125% Senior Notes, due March 2049
450,000 450,000 
Unsecured 3.375% Senior Notes, due September 2049
500,000 500,000 
Unsecured 2.85% Senior Notes, due February 2052
600,000 600,000 
Unsecured 5.75% Senior Notes, due October 2052
500,000 500,000 
Unsecured 6.20% Senior Notes, due November 2053
500,000 500,000 
Unsecured 5.00% Senior Notes, due December 2054
650,000 650,000 
Unsecured 5.45% Senior Notes, due January 2056
600,000 — 
Medium-term note Series A, 1995-1, 6.67%, due December 2025
— 10,000 
Unsecured 6.75% Debentures, due July 2028
150,000 150,000 
Finance lease obligations101,185 47,234 
Total long-term debt10,326,185 8,982,234 
Less:
Original issue (premium) discount on unsecured senior notes and debentures3,135 (1,332)
Debt issuance cost71,792 64,622 
Current maturities of long-term debt502,542 11,775 
Total long-term debt, net$9,748,716 $8,907,169 
v3.26.1
Shareholders' Equity (Tables)
 9 Months Ended
Jun. 30, 2026
Equity [Abstract]  
Schedule of Reconciliation of Changes in Stockholders Equity
The following tables present a reconciliation of changes in stockholders' equity for the three and nine months ended June 30, 2026 and 2025.
Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
(In thousands, except share and per share data)
Balance, September 30, 2025
161,568,384 $808 $8,221,455 $475,015 $4,861,612 $13,558,890 
Net income— — — — 402,964 402,964 
Other comprehensive loss— — — (4,805)— (4,805)
Cash dividends ($1.00 per share)
— — — — (160,407)(160,407)
Common stock issued:
Public and other stock offerings3,709,647 18 474,625 — — 474,643 
Stock-based compensation plans156,446 1 11,606 — — 11,607 
Balance, December 31, 2025165,434,477 827 8,707,686 470,210 5,104,169 14,282,892 
Net income— — — — 581,899 581,899 
Other comprehensive loss— — — (4,938)— (4,938)
Cash dividends ($1.00 per share)
— — — — (168,760)(168,760)
Common stock issued:
Public and other stock offerings1,445,607 7 205,376 — — 205,383 
Stock-based compensation plans38,226 1 12,173 — — 12,174 
Balance, March 31, 2026166,918,310 835 8,925,235 465,272 5,517,308 14,908,650 
Net income— — — — 242,689 242,689 
Other comprehensive loss— — — (4,865)— (4,865)
Cash dividends ($1.00 per share)
— — — — (169,142)(169,142)
Common stock issued:
Public and other stock offerings2,001,479 10 274,109 — — 274,119 
Stock-based compensation plans66,460 — 6,607 — — 6,607 
Balance, June 30, 2026168,986,249 $845 $9,205,951 $460,407 $5,590,855 $15,258,058 
Common stockAdditional
Paid-in
Capital		Accumulated
Other
Comprehensive Income
(Loss)		Retained
Earnings		Total
Number of
Shares		Stated
Value
(In thousands, except share and per share data)
Balance, September 30, 2024
155,258,845 $776 $7,474,559 $465,715 $4,216,619 $12,157,669 
Net income— — — — 351,858 351,858 
Other comprehensive income— — — 16,423 — 16,423 
Cash dividends ($0.87 per share)
— — — — (135,453)(135,453)
Common stock issued:
Public and other stock offerings3,329,358 17 383,520 — — 383,537 
Stock-based compensation plans137,862 1 6,446 — — 6,447 
Balance, December 31, 2024158,726,065 794 7,864,525 482,138 4,433,024 12,780,481 
Net income— — — — 485,576 485,576 
Other comprehensive loss— — — (5,587)— (5,587)
Cash dividends ($0.87 per share)
— — — — (138,416)(138,416)
Common stock issued:
Public and other stock offerings26,367 — 3,841 — — 3,841 
Stock-based compensation plans82,691 — 12,070 — — 12,070 
Balance, March 31, 2025158,835,123 794 7,880,436 476,551 4,780,184 13,137,965 
Net income— — — — 186,429 186,429 
Other comprehensive income— — — 1,409 — 1,409 
Cash dividends ($0.87 per share)
— — — — (138,443)(138,443)
Common stock issued:
Public and other stock offerings1,630,943 8 192,749 — — 192,757 
Stock-based compensation plans54,945 1 5,720 — — 5,721 
Balance, June 30, 2025160,521,011 $803 $8,078,905 $477,960 $4,828,170 $13,385,838 
Schedule of Forward Sales Agreements
MaturityShares AvailableNet Proceeds Available
(In thousands)		Forward Price
December 31, 20262,377,352 $334,047 $140.51 
March 31, 20271,873,444 287,072 $153.23 
June 30, 20271,878,143 315,722 $168.10 
Total6,128,939 $936,841 $152.86 
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, 2025$209 $474,806 $475,015 
Other comprehensive income (loss) before reclassifications(242)— (242)
Amounts reclassified from accumulated other comprehensive income— (14,366)(14,366)
Net current-period other comprehensive income (loss)(242)(14,366)(14,608)
June 30, 2026$(33)$460,440 $460,407 
 
Available-
for-Sale
Securities		Interest Rate
Agreement
Cash Flow
Hedges		Total
(In thousands)
September 30, 2024$213 $465,502 $465,715 
Other comprehensive income (loss) before reclassifications(34)23,400 23,366 
Amounts reclassified from accumulated other comprehensive income— (11,121)(11,121)
Net current-period other comprehensive income (loss)(34)12,279 12,245 
June 30, 2025$179 $477,781 $477,960 
v3.26.1
Securitization (Tables)
 9 Months Ended
Jun. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Condensed Consolidated Balance Sheet
The following table summarizes the impact of AEK on our condensed consolidated balance sheets, for the periods indicated:
June 30, 2026September 30, 2025
(In thousands)
Restricted cash and cash equivalents$4,856 $1,116 
Other current assets$9 $1 
Securitized intangible asset, net$68,026 $75,127 
Accrued interest$1,251 $331 
Current maturities of securitized long-term debt$8,858 $8,767 
Securitized long-term debt$63,751 $68,236 
Schedule of Condensed Consolidated Statements of Comprehensive Income
The following table summarizes the impact of AEK on our condensed consolidated statements of comprehensive income, for the periods indicated:
Three Months Ended June 30Nine Months Ended June 30
2026202520262025
(In thousands)
Operating revenues$3,379 $2,855 $10,183 $9,199 
Operation and maintenance expense(52)(189)(238)(466)
Amortization expense(2,407)(1,646)(7,101)(5,599)
Interest expense, net(920)(1,020)(2,844)(3,134)
Income before income taxes$— $— $— $— 
v3.26.1
Interim Pension and Other Postretirement Benefit Plan Information (Tables)
 9 Months Ended
Jun. 30, 2026
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, 2026 and 2025 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 income.
Three Months Ended June 30
Pension BenefitsOther Benefits
2026202520262025
(In thousands)
Components of net periodic pension cost:
Service cost$2,580 $2,838 $2,018 $2,033 
Interest cost (1)
6,924 6,663 3,634 3,365 
Expected return on assets (1)
(7,949)(7,655)(4,069)(3,831)
Amortization of prior service cost (credit) (1)
— — (2,880)(3,260)
Amortization of actuarial (gain) loss (1)
(51)256 (2,414)(2,429)
Net periodic pension cost$1,504 $2,102 $(3,711)$(4,122)
Nine Months Ended June 30
Pension BenefitsOther Benefits
2026202520262025
(In thousands)
Components of net periodic pension cost:
Service cost$7,740 $8,512 $6,052 $6,099 
Interest cost (1)
20,774 19,989 10,904 10,096 
Expected return on assets (1)
(23,847)(22,964)(12,209)(11,494)
Amortization of prior service cost (credit) (1)
— — (8,639)(9,780)
Amortization of actuarial (gain) loss (1)
(153)767 (7,244)(7,287)
Net periodic pension cost$4,514 $6,304 $(11,136)$(12,366)
(1)    The components of net periodic cost other than the service cost component are included in the line item other non-operating income in the condensed consolidated statements of comprehensive income or are capitalized on the condensed consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended September 30, 2025.
v3.26.1
Financial Instruments (Tables)
 9 Months Ended
Jun. 30, 2026
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, 2026 and September 30, 2025. The gross amounts of recognized assets and liabilities are netted within our condensed consolidated balance sheets to the extent that we have netting arrangements with our counterparties. However, as of June 30, 2026 and September 30, 2025, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
June 30, 2026
Balance Sheet LocationAssetsLiabilities
 (In thousands)
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		$3,824 $(2,822)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		3,026 — 
Total6,850 (2,822)
Gross / Net Financial Instruments$6,850 $(2,822)
 
September 30, 2025
Balance Sheet LocationAssetsLiabilities
 (In thousands)
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities		$5,303 $(6,339)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities		4,594 (146)
Total9,897 (6,485)
Gross / Net Financial Instruments$9,897 $(6,485)
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)
The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income (loss), net of taxes, for the three and nine months ended June 30, 2026 and 2025.
Three Months Ended June 30Nine Months Ended June 30
2026202520262025
(In thousands)
Increase in fair value:
Interest rate agreements$— $5,359 $— $23,400 
Recognition of gains in earnings due to settlements:
Interest rate agreements(4,780)(3,981)(14,366)(11,121)
Total other comprehensive income (loss) from hedging, net of tax$(4,780)$1,378 $(14,366)$12,279 
Schedule of Expected Deferred Gains (Losses) Recognition The following amounts, net of deferred taxes, represent the expected recognition in earnings of the deferred net gains recorded in AOCI associated with our interest rate agreements, based upon the fair values of these agreements at the date of settlement. The remaining amortization periods for these settled amounts
extend through fiscal 2056. 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$19,118 
Thereafter441,323 
Total$460,441 
v3.26.1
Fair Value Measurements (Tables)
 9 Months Ended
Jun. 30, 2026
Fair Value Disclosures [Abstract]  
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of June 30, 2026 and September 30, 2025. Assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement.
Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)		Netting and
Cash
Collateral		June 30, 2026
(In thousands)
Assets:
Financial instruments$— $6,850 $— $— $6,850 
Debt and equity securities
Registered investment companies25,487 — — — 25,487 
Bond mutual funds43,068 — — — 43,068 
Bonds (2)
— 48,660 — — 48,660 
Money market funds— 3,125 — — 3,125 
Total debt and equity securities68,555 51,785 — — 120,340 
Total assets$68,555 $58,635 $— $— $127,190 
Liabilities:
Financial instruments$— $2,822 $— $— $2,822 

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, 2025
(In thousands)
Assets:
Financial instruments$— $9,897 $— $— $9,897 
Debt and equity securities
Registered investment companies26,463 — — — 26,463 
Bond mutual funds42,106 — — — 42,106 
Bonds (2)
— 42,754 — — 42,754 
Money market funds— 3,615 — — 3,615 
Total debt and equity securities68,569 46,369 — — 114,938 
Total assets$68,569 $56,266 $— $— $124,835 
Liabilities:
Financial instruments$— $6,485 $— $— $6,485 
 
(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, 2026 and September 30, 2025:
June 30, 2026September 30, 2025
(In thousands)
Carrying Amount$10,225,000 $8,935,000 
Fair Value$9,379,797 $8,272,978 
v3.26.1
Nature of Business (Details)
customer in Millions
Jun. 30, 2026
customer
state
regulated_distribution_division
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Number of customers serviced (over) | customer 3.4
Number of regulated distribution divisions | regulated_distribution_division 6
Number of states with service areas | state 8
v3.26.1
Regulation (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Regulatory Asset [Line Items]    
Regulatory assets $ 741,631 $ 608,729
Regulatory Liabilities [Line Items]    
Regulatory liabilities 1,294,073 1,269,648
Regulatory excess deferred taxes    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 134,694 190,274
Regulatory cost of removal obligation    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 645,942 641,019
Deferred gas costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 6,844 6,879
APT annual adjustment mechanism    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 182,546 99,393
Pension and postretirement benefit costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 289,505 291,351
Other    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 34,542 40,732
Pension and postretirement benefit costs    
Regulatory Asset [Line Items]    
Regulatory assets 3,857 262
Infrastructure mechanisms    
Regulatory Asset [Line Items]    
Regulatory assets 425,281 314,047
Winter Storm Uri incremental costs    
Regulatory Asset [Line Items]    
Regulatory assets 1,141 5,841
Deferred gas costs    
Regulatory Asset [Line Items]    
Regulatory assets 156,975 140,626
Regulatory excess deferred taxes    
Regulatory Asset [Line Items]    
Regulatory assets 48,718 49,793
Recoverable loss on reacquired debt    
Regulatory Asset [Line Items]    
Regulatory assets 2,777 2,903
Deferred pipeline record collection costs    
Regulatory Asset [Line Items]    
Regulatory assets 35,642 39,035
System Safety and Integrity Riders    
Regulatory Asset [Line Items]    
Regulatory assets 48,801 43,625
Other    
Regulatory Asset [Line Items]    
Regulatory assets $ 18,439 $ 12,597
v3.26.1
Segment Information - Narrative (Details)
 9 Months Ended
Jun. 30, 2026
state
segment
Segment Reporting [Abstract]  
Number of reportable segments | segment 2
Number of states with service areas | state 8
v3.26.1
Segment Information - Schedule of Income Statements and Capital Expenditures By Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]                
Operating revenues $ 879,059     $ 838,774     $ 4,184,046 $ 3,965,275
Operation and maintenance expense 224,669     221,476     631,601 640,210
Depreciation and amortization expense 201,521     185,786     591,853 549,069
Interest charges 33,144     41,537     115,288 144,476
Income tax expense 60,594     44,201     312,902 241,053
Other segment items 345,094     360,091     1,940,943 1,947,101
Net income 242,689 $ 581,899 $ 402,964 186,429 $ 485,576 $ 351,858 1,227,552 1,023,863
Capital expenditures 1,039,346     866,930     3,076,281 2,597,787
Distribution                
Segment Reporting [Line Items]                
Operating revenues 773,909     766,380     3,908,869 3,756,691
Operation and maintenance expense 169,195     165,979     490,481 479,972
Depreciation and amortization expense 148,349     137,106     441,088 405,279
Interest charges 12,870     22,271     66,445 86,607
Income tax expense 15,558     9,731     186,414 147,833
Other segment items 339,301     361,564     1,930,813 1,947,967
Net income 89,385     70,481     795,923 691,337
Capital expenditures 858,790     669,452     2,380,444 1,889,954
Pipeline and Storage                
Segment Reporting [Line Items]                
Operating revenues 105,150     72,394     275,177 208,584
Operation and maintenance expense 55,474     55,497     141,120 160,238
Depreciation and amortization expense 53,172     48,680     150,765 143,790
Interest charges 20,274     19,266     48,843 57,869
Income tax expense 45,036     34,470     126,488 93,220
Other segment items 5,793     (1,473)     10,130 (866)
Net income 153,304     115,948     431,629 332,526
Capital expenditures 180,556     197,478     695,837 707,833
Intersegment eliminations                
Segment Reporting [Line Items]                
Operating revenues (228,652)     (200,746)     (636,093) (580,497)
Intersegment eliminations | Distribution                
Segment Reporting [Line Items]                
Operating revenues (749)     (752)     (2,295) (2,304)
Intersegment eliminations | Pipeline and Storage                
Segment Reporting [Line Items]                
Operating revenues (227,903)     (199,994)     (633,798) (578,193)
Operating Segments                
Segment Reporting [Line Items]                
Operating revenues 1,107,711     1,039,520     4,820,139 4,545,772
Operating Segments | Distribution                
Segment Reporting [Line Items]                
Operating revenues 774,658     767,132     3,911,164 3,758,995
Operating Segments | Pipeline and Storage                
Segment Reporting [Line Items]                
Operating revenues $ 333,053     $ 272,388     $ 908,975 $ 786,777
v3.26.1
Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Segment Reporting [Line Items]    
Net property, plant and equipment $ 28,015,610 $ 25,292,990
Total assets 31,585,539 28,249,522
Operating Segments    
Segment Reporting [Line Items]    
Net property, plant and equipment 28,015,610 25,292,990
Total assets 38,029,124 34,193,451
Operating Segments | Distribution    
Segment Reporting [Line Items]    
Net property, plant and equipment 20,878,848 18,765,128
Total assets 30,490,005 27,296,805
Operating Segments | Pipeline and Storage    
Segment Reporting [Line Items]    
Net property, plant and equipment 7,136,762 6,527,862
Total assets 7,539,119 6,896,646
Intersegment eliminations    
Segment Reporting [Line Items]    
Total assets $ (6,443,585) $ (5,943,929)
v3.26.1
Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2026
Jun. 30, 2025
Basic Earnings Per Share                
Net income $ 242,689 $ 581,899 $ 402,964 $ 186,429 $ 485,576 $ 351,858 $ 1,227,552 $ 1,023,863
Less: Income allocated to participating securities 76     87     370 422
Income available to common shareholders $ 242,613     $ 186,342     $ 1,227,182 $ 1,023,441
Basic weighted average shares outstanding (in shares) 168,345     159,285     165,845 158,245
Net income per share - Basic (USD per share) $ 1.44     $ 1.17     $ 7.40 $ 6.47
Diluted Earnings Per Share                
Income available to common shareholders $ 242,613     $ 186,342     $ 1,227,182 $ 1,023,441
Effect of dilutive shares 0     0     0 0
Income available to common shareholders $ 242,613     $ 186,342     $ 1,227,182 $ 1,023,441
Basic weighted average shares outstanding (in shares) 168,345     159,285     165,845 158,245
Dilutive shares (in shares) 1,029     1,886     1,507 1,553
Diluted weighted average shares outstanding (in shares) 169,374     161,171     167,352 159,798
Net income per share - Diluted (USD per share) $ 1.43     $ 1.16     $ 7.33 $ 6.40
v3.26.1
Revenue and Accounts Receivable - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Disaggregation of Revenue [Line Items]        
Total operating revenues $ 879,059 $ 838,774 $ 4,184,046 $ 3,965,275
Distribution        
Disaggregation of Revenue [Line Items]        
Total operating revenues 773,909 766,380 3,908,869 3,756,691
Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Total operating revenues 105,150 72,394 275,177 208,584
Operating Segments        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,107,711 1,039,520 4,820,139 4,545,772
Operating Segments | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 752,247 762,378 3,732,032 3,699,612
Alternative revenue program revenues 18,588 1,438 167,599 48,657
Other revenues 3,823 3,316 11,533 10,726
Total operating revenues 774,658 767,132 3,911,164 3,758,995
Operating Segments | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 406,263 288,759 1,048,427 828,225
Alternative revenue program revenues (73,210) (16,371) (139,452) (41,448)
Other revenues 0 0 0 0
Total operating revenues 333,053 272,388 908,975 786,777
Operating Segments | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 709,738 723,144 3,597,383 3,573,055
Operating Segments | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Transportation revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 39,498 35,908 125,339 115,987
Operating Segments | Transportation revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 395,186 284,103 1,031,369 816,646
Operating Segments | Miscellaneous revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 3,011 3,326 9,310 10,570
Operating Segments | Miscellaneous revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 11,077 4,656 17,058 11,579
Operating Segments | Residential | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 462,720 473,478 2,462,924 2,475,219
Operating Segments | Residential | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Commercial | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 214,797 213,377 999,363 959,539
Operating Segments | Commercial | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Industrial | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 26,464 27,369 103,804 92,575
Operating Segments | Industrial | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 0 0 0 0
Operating Segments | Public authority and other | Gas sales revenues | Distribution        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers 5,757 8,920 31,292 45,722
Operating Segments | Public authority and other | Gas sales revenues | Pipeline and Storage        
Disaggregation of Revenue [Line Items]        
Revenues from contracts with customers $ 0 $ 0 $ 0 $ 0
v3.26.1
Revenue and Accounts Receivable - Narrative (Details)
 9 Months Ended
Jun. 30, 2026
Disaggregation of Revenue [Line Items]  
Percent of customers excluded (in percentage) 89.00%
Pipeline and storage segment  
Disaggregation of Revenue [Line Items]  
Regulatory mechanism threshold (in percentage) 75.00%
v3.26.1
Revenue and Accounts Receivable - Schedule of Rollforward of Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Accounts Receivable, Allowance for Credit Loss [Roll Forward]        
Beginning balance $ 55,344 $ 49,341 $ 45,259 $ 37,056
Current period provisions 513 1,771 21,998 24,786
Write-offs charged against allowance (4,813) (5,054) (17,679) (17,263)
Recoveries of amounts previously written off 303 302 1,769 1,781
Ending balance $ 51,347 $ 46,360 $ 51,347 $ 46,360
v3.26.1
Debt - Schedule of Long-term Debt Instruments (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Debt Instrument [Line Items]    
Long-term debt $ 10,225,000 $ 8,935,000
Finance lease obligations 101,185 47,234
Total long-term debt 10,326,185 8,982,234
Less:    
Original issue (premium) discount on unsecured senior notes and debentures 3,135 (1,332)
Debt issuance cost 71,792 64,622
Current maturities of long-term debt 502,542 11,775
Total long-term debt, net $ 9,748,716 8,907,169
Unsecured 3.00% Senior Notes, due June 2027    
Debt Instrument [Line Items]    
Interest rate 3.00%  
Long-term debt $ 500,000 500,000
Unsecured 2.625% Senior Notes, due September 2029    
Debt Instrument [Line Items]    
Interest rate 2.625%  
Long-term debt $ 500,000 500,000
Unsecured 1.50% Senior Notes, due January 2031    
Debt Instrument [Line Items]    
Interest rate 1.50%  
Long-term debt $ 600,000 600,000
Unsecured 4.75% Senior Notes, due January 2032    
Debt Instrument [Line Items]    
Interest rate 4.75%  
Long-term debt $ 700,000 0
Unsecured 5.45% Senior Notes, due October 2032    
Debt Instrument [Line Items]    
Interest rate 5.45%  
Long-term debt $ 300,000 300,000
Unsecured 5.90% Senior Notes, due November 2033    
Debt Instrument [Line Items]    
Interest rate 5.90%  
Long-term debt $ 725,000 725,000
Unsecured 5.95% Senior Notes, due October 2034    
Debt Instrument [Line Items]    
Interest rate 5.95%  
Long-term debt $ 200,000 200,000
Unsecured 5.20% Senior Notes, due August 2035    
Debt Instrument [Line Items]    
Interest rate 5.20%  
Long-term debt $ 500,000 500,000
Unsecured 5.50% Senior Notes, due June 2041    
Debt Instrument [Line Items]    
Interest rate 5.50%  
Long-term debt $ 400,000 400,000
Unsecured 4.15% Senior Notes, due January 2043    
Debt Instrument [Line Items]    
Interest rate 4.15%  
Long-term debt $ 500,000 500,000
Unsecured 4.125% Senior Notes, due October 2044    
Debt Instrument [Line Items]    
Interest rate 4.125%  
Long-term debt $ 750,000 750,000
Unsecured 4.30% Senior Notes, due October 2048    
Debt Instrument [Line Items]    
Interest rate 4.30%  
Long-term debt $ 600,000 600,000
Unsecured 4.125% Senior Notes, due March 2049    
Debt Instrument [Line Items]    
Interest rate 4.125%  
Long-term debt $ 450,000 450,000
Unsecured 3.375% Senior Notes, due September 2049    
Debt Instrument [Line Items]    
Interest rate 3.375%  
Long-term debt $ 500,000 500,000
Unsecured 2.85% Senior Notes, due February 2052    
Debt Instrument [Line Items]    
Interest rate 2.85%  
Long-term debt $ 600,000 600,000
Unsecured 5.75% Senior Notes, due October 2052    
Debt Instrument [Line Items]    
Interest rate 5.75%  
Long-term debt $ 500,000 500,000
Unsecured 6.20% Senior Notes, due November 2053    
Debt Instrument [Line Items]    
Interest rate 6.20%  
Long-term debt $ 500,000 500,000
Unsecured 5.00% Senior Notes, due December 2054    
Debt Instrument [Line Items]    
Interest rate 5.00%  
Long-term debt $ 650,000 650,000
Unsecured 5.45% Senior Notes, due January 2056    
Debt Instrument [Line Items]    
Interest rate 5.45%  
Long-term debt $ 600,000 0
Medium-term note Series A, 1995-1, 6.67%, due December 2025    
Debt Instrument [Line Items]    
Interest rate 6.67%  
Long-term debt $ 0 10,000
Unsecured 6.75% Debentures, due July 2028    
Debt Instrument [Line Items]    
Interest rate 6.75%  
Long-term debt $ 150,000 $ 150,000
v3.26.1
Debt - Narrative (Details)
 9 Months Ended
Jun. 18, 2026
USD ($)
Apr. 01, 2026
USD ($)
Mar. 31, 2026
USD ($)
Oct. 01, 2025
USD ($)
Jun. 30, 2026
USD ($)
credit_facility
Jun. 30, 2025
USD ($)
Sep. 30, 2025
USD ($)
Line Of Credit Facility [Line Items]              
Proceeds from issuance of long-term debt         $ 1,296,231,000 $ 1,143,447,000  
Maximum debt-to-total-capitalization ratio (in percentage)         70.00%    
Debt-to-total-capitalization ratio (in percentage)         0.41    
Minimum              
Line Of Credit Facility [Line Items]              
Outstanding indebtedness         $ 15,000,000    
Maximum              
Line Of Credit Facility [Line Items]              
Outstanding indebtedness         $ 100,000,000    
Unsecured 5.45% Senior Notes, due January 2056              
Line Of Credit Facility [Line Items]              
Interest rate         5.45%    
Unsecured 5.45% Senior Notes, due January 2056 | Senior Notes              
Line Of Credit Facility [Line Items]              
Debt face amount       $ 600,000,000      
Interest rate       5.45%      
Effective rate       4.85%      
Proceeds from issuance of long-term debt       $ 590,000,000.0      
Unsecured 4.75% Senior Notes, due January 2032              
Line Of Credit Facility [Line Items]              
Interest rate         4.75%    
Unsecured 4.75% Senior Notes, due January 2032 | Senior Notes              
Line Of Credit Facility [Line Items]              
Debt face amount $ 700,000,000            
Interest rate 4.75%            
Effective rate 4.92%            
Proceeds from issuance of long-term debt $ 694,000,000.0            
Five Year Unsecured Revolving Credit Agreement | Commercial Paper              
Line Of Credit Facility [Line Items]              
Maximum borrowing capacity         $ 1,500,000,000    
Debt agreement term (in years)         5 years    
Five Year Unsecured Revolving Credit Agreement, March 28, 2030              
Line Of Credit Facility [Line Items]              
Outstanding commercial paper         $ 0   $ 0
Five Year Unsecured Revolving Credit Agreement, March 28, 2030 | Minimum | Base Rate              
Line Of Credit Facility [Line Items]              
Interest rate spread         0.00%    
Five Year Unsecured Revolving Credit Agreement, March 28, 2030 | Minimum | Term SOFR              
Line Of Credit Facility [Line Items]              
Interest rate spread         0.75%    
Five Year Unsecured Revolving Credit Agreement, March 28, 2030 | Maximum | Base Rate              
Line Of Credit Facility [Line Items]              
Interest rate spread         0.25%    
Five Year Unsecured Revolving Credit Agreement, March 28, 2030 | Maximum | Term SOFR              
Line Of Credit Facility [Line Items]              
Interest rate spread         1.25%    
Five Year Unsecured Revolving Credit Agreement, March 28, 2030 | 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    
Five Year Unsecured Revolving Credit Agreement, March 28, 2030 | Revolving Credit Facility              
Line Of Credit Facility [Line Items]              
Maximum borrowing capacity         $ 3,100,000,000    
Number of credit facilities | credit_facility         4    
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility              
Line Of Credit Facility [Line Items]              
Maximum borrowing capacity         $ 1,500,000,000    
Debt agreement term (in years)         3 years    
Accordion feature         $ 250,000,000    
Maximum borrowing capacity post accordion feature         1,750,000,000    
Outstanding borrowings         $ 0   0
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Base Rate              
Line Of Credit Facility [Line Items]              
Interest rate spread         0.00%    
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Term SOFR              
Line Of Credit Facility [Line Items]              
Interest rate spread         0.75%    
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Base Rate              
Line Of Credit Facility [Line Items]              
Interest rate spread         0.25%    
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Term SOFR              
Line Of Credit Facility [Line Items]              
Interest rate spread         1.25%    
$50 Million Bank Loan Agreement | Line of Credit              
Line Of Credit Facility [Line Items]              
Maximum borrowing capacity   $ 50,000,000          
Debt agreement term (in years)   364 days          
Outstanding borrowings         $ 0   $ 0
$50 Million Revolving Credit Facility              
Line Of Credit Facility [Line Items]              
Outstanding borrowings         0    
$50 Million Revolving Credit Facility | Revolving Credit Facility              
Line Of Credit Facility [Line Items]              
Maximum borrowing capacity     $ 50,000,000        
Debt agreement term (in years)     364 days        
Remaining borrowing capacity         $ 44,400,000    
v3.26.1
Shareholders' Equity - Schedule of Reconciliation of Changes in Stockholders Equity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2026
Jun. 30, 2025
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Common stock outstanding, beginning balance (in shares)     161,568,384       161,568,384  
Shareholders' equity, beginning balance $ 14,908,650 $ 14,282,892 $ 13,558,890 $ 13,137,965 $ 12,780,481 $ 12,157,669 $ 13,558,890 $ 12,157,669
Net income 242,689 581,899 402,964 186,429 485,576 351,858 1,227,552 1,023,863
Other comprehensive (loss) income (4,865) (4,938) (4,805) 1,409 (5,587) 16,423 $ (14,608) 12,245
Cash dividends (169,142) (168,760) (160,407) (138,443) (138,416) (135,453)    
Public and other stock offerings 274,119 205,383 474,643 192,757 3,841 383,537    
Stock-based compensation plans $ 6,607 12,174 11,607 5,721 12,070 6,447    
Common stock outstanding, ending balance (in shares) 168,986,249           168,986,249  
Shareholders' equity, ending balance $ 15,258,058 $ 14,908,650 $ 14,282,892 $ 13,385,838 $ 13,137,965 $ 12,780,481 $ 15,258,058 $ 13,385,838
Cash dividends per share (USD per share) $ 1.00 $ 1.00 $ 1.00 $ 0.87 $ 0.87 $ 0.87 $ 3.00 $ 2.61
Common stock                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Common stock outstanding, beginning balance (in shares) 166,918,310 165,434,477 161,568,384 158,835,123 158,726,065 155,258,845 161,568,384 155,258,845
Shareholders' equity, beginning balance $ 835 $ 827 $ 808 $ 794 $ 794 $ 776 $ 808 $ 776
Public and other stock offerings (in shares) 2,001,479 1,445,607 3,709,647 1,630,943 26,367 3,329,358    
Public and other stock offerings $ 10 $ 7 $ 18 $ 8   $ 17    
Stock-based compensation plans (in shares) 66,460 38,226 156,446 54,945 82,691 137,862    
Stock-based compensation plans $ 0 $ 1 $ 1 $ 1   $ 1    
Common stock outstanding, ending balance (in shares) 168,986,249 166,918,310 165,434,477 160,521,011 158,835,123 158,726,065 168,986,249 160,521,011
Shareholders' equity, ending balance $ 845 $ 835 $ 827 $ 803 $ 794 $ 794 $ 845 $ 803
Additional Paid-in Capital                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Shareholders' equity, beginning balance 8,925,235 8,707,686 8,221,455 7,880,436 7,864,525 7,474,559 8,221,455 7,474,559
Public and other stock offerings 274,109 205,376 474,625 192,749 3,841 383,520    
Stock-based compensation plans 6,607 12,173 11,606 5,720 12,070 6,446    
Shareholders' equity, ending balance 9,205,951 8,925,235 8,707,686 8,078,905 7,880,436 7,864,525 9,205,951 8,078,905
Accumulated Other Comprehensive Income (Loss)                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Shareholders' equity, beginning balance 465,272 470,210 475,015 476,551 482,138 465,715 475,015 465,715
Other comprehensive (loss) income (4,865) (4,938) (4,805) 1,409 (5,587) 16,423    
Shareholders' equity, ending balance 460,407 465,272 470,210 477,960 476,551 482,138 460,407 477,960
Retained Earnings                
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Shareholders' equity, beginning balance 5,517,308 5,104,169 4,861,612 4,780,184 4,433,024 4,216,619 4,861,612 4,216,619
Net income 242,689 581,899 402,964 186,429 485,576 351,858    
Cash dividends (169,142) (168,760) (160,407) (138,443) (138,416) (135,453)    
Shareholders' equity, ending balance $ 5,590,855 $ 5,517,308 $ 5,104,169 $ 4,828,170 $ 4,780,184 $ 4,433,024 $ 5,590,855 $ 4,828,170
v3.26.1
Shareholders' Equity - Narrative (Details) - USD ($)
$ in Thousands
 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Class of Stock [Line Items]    
Net proceeds from equity issuances $ 941,694 $ 568,603
Forward sales equity agreement, settlement in cash 936,841  
Shelf Registration Statement    
Class of Stock [Line Items]    
Debt and equity securities authorized for issuance 8,000,000  
Debt and equity securities authorized for issuance value remaining 4,500,000  
At-The-Market    
Class of Stock [Line Items]    
Value of shares authorized for issuance $ 1,700,000  
Shares issued (in shares) 7,084,863  
Net proceeds from equity issuances $ 941,700  
Equity available for issuance $ 506,500  
v3.26.1
Shareholders' Equity - Schedule of Forward Sales Agreement (Details)
$ / shares in Units, $ in Thousands
 9 Months Ended
Jun. 30, 2026
USD ($)
$ / shares
shares
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 6,128,939
Net proceeds available | $ $ 936,841
Forward price (USD per share) | $ / shares $ 152.86
Forward Sales Equity Agreement Maturing Quarter December 31, 2026  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 2,377,352
Net proceeds available | $ $ 334,047
Forward price (USD per share) | $ / shares $ 140.51
Forward Sales Equity Agreement Maturing Quarter March 31, 2027  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 1,873,444
Net proceeds available | $ $ 287,072
Forward price (USD per share) | $ / shares $ 153.23
Forward Sales Equity Agreement Maturing Quarter June 30, 2027  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares available (in shares) | shares 1,878,143
Net proceeds available | $ $ 315,722
Forward price (USD per share) | $ / shares $ 168.10
v3.26.1
Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2026
Jun. 30, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance $ 14,908,650 $ 14,282,892 $ 13,558,890 $ 13,137,965 $ 12,780,481 $ 12,157,669 $ 13,558,890 $ 12,157,669
Other comprehensive income (loss) before reclassifications             (242) 23,366
Amounts reclassified from accumulated other comprehensive income             (14,366) (11,121)
Total other comprehensive income (loss) (4,865) (4,938) (4,805) 1,409 (5,587) 16,423 (14,608) 12,245
Shareholders' equity, ending balance 15,258,058 14,908,650 14,282,892 13,385,838 13,137,965 12,780,481 15,258,058 13,385,838
Accumulated Other Comprehensive Income (Loss)                
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance 465,272 470,210 475,015 476,551 482,138 465,715 475,015 465,715
Total other comprehensive income (loss) (4,865) (4,938) (4,805) 1,409 (5,587) 16,423    
Shareholders' equity, ending balance 460,407 $ 465,272 470,210 477,960 $ 476,551 482,138 460,407 477,960
Available- for-Sale Securities                
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance     209     213 209 213
Other comprehensive income (loss) before reclassifications             (242) (34)
Amounts reclassified from accumulated other comprehensive income             0 0
Total other comprehensive income (loss)             (242) (34)
Shareholders' equity, ending balance (33)     179     (33) 179
Interest Rate Agreement Cash Flow Hedges                
AOCI Attributable to Parent, Net of Tax [Roll Forward]                
Shareholders' equity, beginning balance     $ 474,806     $ 465,502 474,806 465,502
Other comprehensive income (loss) before reclassifications             0 23,400
Amounts reclassified from accumulated other comprehensive income             (14,366) (11,121)
Total other comprehensive income (loss)             (14,366) 12,279
Shareholders' equity, ending balance $ 460,440     $ 477,781     $ 460,440 $ 477,781
v3.26.1
Securitization - Narrative (Details) - USD ($)
$ in Thousands
 1 Months Ended
Mar. 31, 2023
Jun. 30, 2026
Sep. 30, 2025
Jun. 30, 2023
Variable Interest Entity [Line Items]        
Long-term debt, fair value   $ 9,379,797 $ 8,272,978  
Variable Interest Entity, Primary Beneficiary | Texas | Extraordinary Gas Cost | Winter Storm Uri        
Variable Interest Entity [Line Items]        
Regulatory asset, authorized $ 3,500,000      
Variable Interest Entity, Primary Beneficiary | Texas | Extraordinary Gas Cost | Winter Storm Uri | Minimum        
Variable Interest Entity [Line Items]        
Regulatory asset, maturity period (in years) 12 years      
Variable Interest Entity, Primary Beneficiary | Texas | Extraordinary Gas Cost | Winter Storm Uri | Maximum        
Variable Interest Entity [Line Items]        
Regulatory asset, maturity period (in years) 18 years      
Securitized Utility Tariff Bonds | Senior Notes | Variable Interest Entity, Primary Beneficiary        
Variable Interest Entity [Line Items]        
Debt face amount       $ 95,000
Long-term debt   72,600 77,000  
Long-term debt, fair value   $ 73,200 $ 78,800  
v3.26.1
Securitization - Schedule of Condensed Consolidated Balance Sheet (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents $ 4,856 $ 1,116
Other current assets 351,150 301,627
Securitized intangible asset, net 68,026 75,127
Current maturities of securitized long-term debt 8,858 8,767
Securitized long-term debt 63,751 68,236
Variable Interest Entity, Primary Beneficiary    
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents 4,856 1,116
Other current assets 9 1
Securitized intangible asset, net 68,026 75,127
Accrued interest 1,251 331
Current maturities of securitized long-term debt 8,858 8,767
Securitized long-term debt $ 63,751 $ 68,236
v3.26.1
Securitization - Schedule of Consolidated Statements of Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Variable Interest Entity [Line Items]        
Operating revenues $ 879,059 $ 838,774 $ 4,184,046 $ 3,965,275
Operation and maintenance expense (223,162) (222,100) (648,762) (662,440)
Amortization expense (201,521) (185,786) (591,853) (549,069)
Interest expense, net (33,144) (41,537) (115,288) (144,476)
Income before income taxes 303,283 230,630 1,540,454 1,264,916
Variable Interest Entity, Primary Beneficiary        
Variable Interest Entity [Line Items]        
Operating revenues 3,379 2,855 10,183 9,199
Operation and maintenance expense (52) (189) (238) (466)
Amortization expense (2,407) (1,646) (7,101) (5,599)
Interest expense, net (920) (1,020) (2,844) (3,134)
Income before income taxes $ 0 $ 0 $ 0 $ 0
v3.26.1
Interim Pension and Other Postretirement Benefit Plan Information (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Pension Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 2,580 $ 2,838 $ 7,740 $ 8,512
Interest cost 6,924 6,663 20,774 19,989
Expected return on assets (7,949) (7,655) (23,847) (22,964)
Amortization of prior service cost (credit) 0 0 0 0
Amortization of actuarial (gain) loss (51) 256 (153) 767
Net periodic pension cost 1,504 2,102 4,514 6,304
Other Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 2,018 2,033 6,052 6,099
Interest cost 3,634 3,365 10,904 10,096
Expected return on assets (4,069) (3,831) (12,209) (11,494)
Amortization of prior service cost (credit) (2,880) (3,260) (8,639) (9,780)
Amortization of actuarial (gain) loss (2,414) (2,429) (7,244) (7,287)
Net periodic pension cost $ (3,711) $ (4,122) $ (11,136) $ (12,366)
v3.26.1
Commitments and Contingencies (Details)
 9 Months Ended
Jan. 27, 2024
incident
fatality
Jun. 30, 2026
$ / Mcf
MMcf
May 28, 2026
fatality
Dec. 02, 2024
fatality
Supply Commitment        
Long-term Purchase Commitment [Line Items]        
Contract term (in years)   1 year    
Supply Commitment | Short-term Contract with Customer        
Long-term Purchase Commitment [Line Items]        
Contract term (in years)   1 year    
Purchase commitment volume | MMcf   69,200    
Supply Commitment | Long-term Contract with Customer Within Two To Three Years        
Long-term Purchase Commitment [Line Items]        
Purchase commitment volume | MMcf   52,400    
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Minimum        
Long-term Purchase Commitment [Line Items]        
Contract term (in years)   2 years    
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Maximum        
Long-term Purchase Commitment [Line Items]        
Contract term (in years)   3 years    
Supply Commitment | Fixed-Price Contracts        
Long-term Purchase Commitment [Line Items]        
Contract term (in years)   1 year    
Purchase commitment volume | MMcf   7,900    
Supply Commitment | Fixed-Price Contracts | Weighted Average        
Long-term Purchase Commitment [Line Items]        
Fixed price contracts (USD per Mcf) | $ / Mcf   3.03    
National Transportation Safety Board | Jackson, Mississippi        
Long-term Purchase Commitment [Line Items]        
Number of incidents investigated that occurred during period | incident 2      
Number of fatalities under investigation | fatality 1      
National Transportation Safety Board | Avondale, Louisiana        
Long-term Purchase Commitment [Line Items]        
Number of fatalities under investigation | fatality       1
National Transportation Safety Board | Dallas, Texas        
Long-term Purchase Commitment [Line Items]        
Number of fatalities under investigation | fatality     3  
v3.26.1
Income Taxes (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Sep. 30, 2025
Income Tax Contingency [Line Items]          
Effective income tax rate 20.00% 19.20% 20.30% 19.10%  
Deferred tax liabilities, net $ 86,000   $ 86,000    
Regulatory liabilities 1,294,073   1,294,073   $ 1,269,648
Regulatory excess deferred taxes          
Income Tax Contingency [Line Items]          
Regulatory liabilities 134,694   134,694   190,274
Regulatory excess deferred taxes | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent          
Income Tax Contingency [Line Items]          
Deferred tax liabilities, net 34,400   34,400   $ 72,800
Regulatory excess deferred taxes, to be returned, tranche one          
Income Tax Contingency [Line Items]          
Deferred tax liabilities, net 38,600   $ 38,600    
Regulatory excess deferred taxes, to be returned, tranche one | Minimum          
Income Tax Contingency [Line Items]          
Return basis, term (in years)     36 months    
Regulatory excess deferred taxes, to be returned, tranche one | Maximum          
Income Tax Contingency [Line Items]          
Return basis, term (in years)     60 months    
Regulatory excess deferred taxes, to be returned, tranche two          
Income Tax Contingency [Line Items]          
Regulatory liabilities 46,400   $ 46,400    
Regulatory excess deferred taxes, to be returned, tranche two | Minimum          
Income Tax Contingency [Line Items]          
Return basis, term (in years)     15 years    
Regulatory excess deferred taxes, to be returned, tranche two | Maximum          
Income Tax Contingency [Line Items]          
Return basis, term (in years)     46 years    
Regulatory excess deferred taxes, to be returned, tranche three          
Income Tax Contingency [Line Items]          
Deferred tax liabilities, net $ 1,000   $ 1,000    
v3.26.1
Financial Instruments - Narrative (Details)
 3 Months Ended 9 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
MMcf
Jun. 30, 2025
USD ($)
Sep. 30, 2025
USD ($)
Derivative [Line Items]          
Purchase commitment volume | MMcf     18,662    
Contract netting $ 0   $ 0   $ 0
Cash collateral 0   0   $ 0
Net (gain) loss on settled interest rate agreements (6,100,000) $ (5,100,000) (18,400,000) $ (15,400,000)  
Net realized gains in AOCI $ 460,400,000   $ 460,400,000    
Designated As Hedge | Gas Purchases | Commodity contracts          
Derivative [Line Items]          
Purchase commitment volume | MMcf     23,800    
Designated As Hedge | Gas Purchases | Commodity contracts | Minimum          
Derivative [Line Items]          
Hedging percent 25.00%   25.00%    
Designated As Hedge | Gas Purchases | Commodity contracts | Maximum          
Derivative [Line Items]          
Hedging percent 50.00%   50.00%    
v3.26.1
Financial Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets $ 6,850 $ 9,897
Gross/net financial instruments, liabilities (2,822) (6,485)
Not Designated As Hedges:    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 6,850 9,897
Gross/net financial instruments, liabilities (2,822) (6,485)
Not Designated As Hedges: | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssetsCurrent | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 3,824 5,303
Not Designated As Hedges: | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssetsNoncurrent | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, assets 3,026 4,594
Not Designated As Hedges: | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesCurrent | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities (2,822) (6,339)
Not Designated As Hedges: | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent | Commodity contracts    
Derivatives Fair Value [Line Items]    
Gross/net financial instruments, liabilities $ 0 $ (146)
v3.26.1
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, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Increase in fair value:        
Interest rate agreements $ 0 $ 5,359 $ 0 $ 23,400
Recognition of gains in earnings due to settlements:        
Interest rate agreements (4,780) (3,981) (14,366) (11,121)
Total other comprehensive income (loss) from hedging, net of tax $ (4,780) $ 1,378 $ (14,366) $ 12,279
v3.26.1
Financial Instruments - Schedule Of Expected Deferred Gains (Losses) Recognition (Details)
$ in Thousands
 9 Months Ended
Jun. 30, 2026
USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Next twelve months $ 19,118
Thereafter 441,323
Total $ 460,441
v3.26.1
Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments net assets $ 6,850 $ 9,897
Total debt and equity securities 120,340 114,938
Total assets 127,190 124,835
Financial instruments net liability 2,822 6,485
Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 25,487 26,463
Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 43,068 42,106
Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Bonds 48,660 42,754
Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 3,125 3,615
Quoted Prices in Active Markets (Level 1)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments gross assets 0 0
Total debt and equity securities 68,555 68,569
Total assets 68,555 68,569
Financial instruments gross liability 0 0
Quoted Prices in Active Markets (Level 1) | Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 25,487 26,463
Quoted Prices in Active Markets (Level 1) | Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 43,068 42,106
Quoted Prices in Active Markets (Level 1) | Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Bonds 0 0
Quoted Prices in Active Markets (Level 1) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Observable Inputs (Level 2)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments gross assets 6,850 9,897
Total debt and equity securities 51,785 46,369
Total assets 58,635 56,266
Financial instruments gross liability 2,822 6,485
Significant Other Observable Inputs (Level 2) | Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Observable Inputs (Level 2) | Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Observable Inputs (Level 2) | Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Bonds 48,660 42,754
Significant Other Observable Inputs (Level 2) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 3,125 3,615
Significant Other Unobservable Inputs (Level 3)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments gross assets 0 0
Total debt and equity securities 0 0
Total assets 0 0
Financial instruments gross liability 0 0
Significant Other Unobservable Inputs (Level 3) | Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Unobservable Inputs (Level 3) | Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 0 0
Significant Other Unobservable Inputs (Level 3) | Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Bonds 0 0
Significant Other Unobservable Inputs (Level 3) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities $ 0 $ 0
v3.26.1
Fair Value Measurements - Narrative (Details) - USD ($)
Jun. 30, 2026
Sep. 30, 2025
Fair Value Disclosures [Abstract]    
Allowance for credit losses $ 0  
Cost basis $ 48,700,000 $ 42,500,000
v3.26.1
Fair Value Measurements - Schedule of Carrying Values and Estimated Fair Values of Long-term Debt (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Fair Value Disclosures [Abstract]    
Carrying Amount $ 10,225,000 $ 8,935,000
Fair Value $ 9,379,797 $ 8,272,978