ATMOS ENERGY CORP, 10-K filed on 11/14/2025
Annual Report
v3.25.3
Cover - USD ($)
12 Months Ended
Sep. 30, 2025
Nov. 10, 2025
Mar. 31, 2025
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Sep. 30, 2025    
Current Fiscal Year End Date --09-30    
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 Well Known Seasoned Issuer Yes    
Entity Voluntary Filers No    
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    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction false    
Entity Shell Company false    
Entity Public Float     $ 24,413,133,216
Entity Common Stock Shares Outstanding   161,693,336  
Documents Incorporated by Reference Portions of the registrant’s Definitive Proxy Statement to be filed for the Annual Meeting of Shareholders on February 4, 2026 are incorporated by reference into Part III of this report.    
Entity Central Index Key 0000731802    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Amendment Flag false    
v3.25.3
Audit Information
12 Months Ended
Sep. 30, 2025
Auditor Information [Abstract]  
Auditor Name Ernst & Young LLP
Auditor Firm ID 42
Auditor Location Dallas, Texas
v3.25.3
CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
ASSETS    
Property, plant and equipment $ 28,028,820 $ 24,784,285
Construction in progress 1,235,316 1,063,798
Total property, plant and equipment and construction in progress 29,264,136 25,848,083
Less accumulated depreciation and amortization 3,971,146 3,643,716
Net property, plant and equipment 25,292,990 22,204,367
Current assets    
Cash and cash equivalents 202,687 307,340
Restricted cash and cash equivalents 1,116 1,516
Cash and cash equivalents and restricted cash and cash equivalents 203,803 308,856
Accounts receivable, less allowance for uncollectible accounts of $45,259 in 2025 and $37,056 in 2024 375,509 365,882
Gas stored underground 171,756 169,508
Other current assets 301,627 288,068
Total current assets 1,052,695 1,132,314
Securitized intangible asset, less accumulated amortization of $18,473 in 2025 and $10,756 in 2024 (See Note 10) 75,127 82,844
Goodwill 731,257 731,257
Deferred charges and other assets 1,097,453 1,043,683
Total assets 28,249,522 25,194,465
Shareholders’ equity    
Common stock, no par value (stated at $0.005 per share); 200,000,000 shares authorized; issued and outstanding: 2025 — 161,568,384 shares; 2024 — 155,258,845 shares 808 776
Additional paid-in capital 8,221,455 7,474,559
Accumulated other comprehensive income 475,015 465,715
Retained earnings 4,861,612 4,216,619
Shareholders’ equity 13,558,890 12,157,669
Long-term debt 8,907,169 7,783,646
Securitized long-term debt (See Note 10) 68,236 76,871
Total capitalization 22,534,295 20,018,186
Commitments and contingencies (See Note 14)
Current liabilities    
Accounts payable and accrued liabilities 506,516 445,397
Other current liabilities 835,557 750,620
Current maturities of long-term debt 11,775 1,651
Current maturities of securitized long-term debt (See Note 10) 8,767 8,207
Total current liabilities 1,362,615 1,205,875
Deferred income taxes 2,918,347 2,593,342
Regulatory excess deferred taxes (See Note 15) 117,482 177,315
Regulatory cost of removal obligation 532,461 507,815
Deferred credits and other liabilities 784,322 691,932
Total shareholders' equity and liabilities $ 28,249,522 $ 25,194,465
v3.25.3
CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Statement of Financial Position [Abstract]    
Accounts receivable, allowance for uncollectible accounts $ 45,259 $ 37,056
Securitized intangible asset, accumulated amortization $ 18,473 $ 10,756
Common stock stated value per share (USD per share) $ 0.005 $ 0.005
Common stock shares authorized (in shares) 200,000,000 200,000,000
Common stock shares issued (in shares) 161,568,384 155,258,845
Common stock shares outstanding (in shares) 161,568,384 155,258,845
v3.25.3
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
shares in Thousands, $ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Operating revenues $ 4,702,755 $ 4,165,187 $ 4,275,357
Purchased gas cost 1,066,054 933,693 1,452,173
Operation and maintenance expense 902,942 819,137 764,906
Depreciation and amortization expense 734,745 669,972 604,327
Taxes, other than income 439,043 387,023 386,804
Operating income 1,559,971 1,355,362 1,067,147
Other non-operating income 89,741 71,046 69,775
Interest charges 171,678 190,632 137,281
Income before income taxes 1,478,034 1,235,776 999,641
Income tax expense 279,280 192,881 113,779
Net income $ 1,198,754 $ 1,042,895 $ 885,862
Basic net income per share (USD per share) $ 7.54 $ 6.83 $ 6.10
Diluted net income per share (USD per share) $ 7.46 $ 6.83 $ 6.10
Weighted average shares outstanding:      
Basic (in shares) 158,943 152,508 145,121
Diluted (in shares) 160,573 152,666 145,166
Other comprehensive income (loss), net of tax      
Net unrealized holding gains (losses) on available-for-sale securities, net of tax of $(3), $168 and $37 $ (4) $ 582 $ 126
Cash flow hedges:      
Amortization and unrealized gains (losses) on interest rate agreements, net of tax of $1,103, $(15,432) and $43,148 9,304 (53,395) 149,290
Total other comprehensive income (loss) 9,300 (52,813) 149,416
Total comprehensive income 1,208,054 990,082 1,035,278
Distribution segment      
Operating revenues 4,422,355 3,912,134 4,096,661
Depreciation and amortization expense 543,840 491,982 434,721
Interest charges 99,226 117,086 77,185
Income tax expense 150,961 96,041 60,032
Net income 746,781 671,413 580,397
Pipeline and storage segment      
Operating revenues 280,400 253,053 178,696
Depreciation and amortization expense 190,905 177,990 169,606
Interest charges 72,452 73,546 60,096
Income tax expense 128,319 96,840 53,747
Net income 451,973 371,482 305,465
Operating Segments      
Operating revenues 5,490,697 4,853,170 4,884,864
Operating Segments | Distribution segment      
Operating revenues 4,425,397 3,915,141 4,099,690
Purchased gas cost 1,854,323 1,620,515 2,061,920
Operating Segments | Pipeline and storage segment      
Operating revenues 1,065,300 938,029 785,174
Purchased gas cost (1,346) 146 (1,220)
Intersegment eliminations      
Operating revenues (787,942) (687,983) (609,507)
Purchased gas cost (786,923) (686,968) (608,527)
Intersegment eliminations | Distribution segment      
Operating revenues (3,042) (3,007) (3,029)
Intersegment eliminations | Pipeline and storage segment      
Operating revenues $ (784,900) $ (684,976) $ (606,478)
v3.25.3
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Statement of Comprehensive Income [Abstract]      
Net unrealized holding gains (losses) on available-for-sale securities, tax $ (3) $ 168 $ 37
Amortization and unrealized gains (losses) on interest rate agreements, tax $ 1,103 $ (15,432) $ 43,148
v3.25.3
CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($)
$ in Thousands
Total
Common stock
Additional Paid-in Capital
Accumulated Other Comprehensive Income (Loss)
Retained Earnings
Common stock shares outstanding, balance (in shares) at Sep. 30, 2022   140,896,598      
Shareholders' equity, beginning balance at Sep. 30, 2022 $ 9,419,091 $ 704 $ 5,838,118 $ 369,112 $ 3,211,157
Increase (Decrease) in Stockholders' Equity [Roll Forward]          
Net income 885,862       885,862
Other comprehensive income (loss) 149,416     149,416  
Cash dividends (430,345)       (430,345)
Common stock issued:          
Public offering (in shares)   7,272,261      
Public offering 806,949 $ 36 806,913    
Direct stock purchase plan (in shares)   64,871      
Direct stock purchase plan 7,429   7,429    
Retirement savings plan (in shares)   69,716      
Retirement savings plan 7,966 $ 1 7,965    
1998 Long-term incentive plan (in shares)   189,337      
1998 Long-term incentive plan 2,108 $ 1 2,107    
Employee stock-based compensation 21,588   21,588    
Common stock shares outstanding, ending balance (in shares) at Sep. 30, 2023   148,492,783      
Shareholders' equity, ending balance at Sep. 30, 2023 10,870,064 $ 742 6,684,120 518,528 3,666,674
Increase (Decrease) in Stockholders' Equity [Roll Forward]          
Net income 1,042,895       1,042,895
Other comprehensive income (loss) (52,813)     (52,813)  
Cash dividends (492,950)       (492,950)
Common stock issued:          
Public offering (in shares)   6,401,469      
Public offering 749,987 $ 32 749,955    
Direct stock purchase plan (in shares)   60,756      
Direct stock purchase plan 7,129   7,129    
Retirement savings plan (in shares)   67,134      
Retirement savings plan 7,955 $ 1 7,954    
1998 Long-term incentive plan (in shares)   236,703      
1998 Long-term incentive plan 2,198 $ 1 2,197    
Employee stock-based compensation $ 23,204   23,204    
Common stock shares outstanding, ending balance (in shares) at Sep. 30, 2024 155,258,845 155,258,845      
Shareholders' equity, ending balance at Sep. 30, 2024 $ 12,157,669 $ 776 7,474,559 465,715 4,216,619
Increase (Decrease) in Stockholders' Equity [Roll Forward]          
Net income 1,198,754       1,198,754
Other comprehensive income (loss) 9,300     9,300  
Cash dividends (553,761)       (553,761)
Common stock issued:          
Public offering (in shares)   5,931,289      
Public offering 698,462 $ 30 698,432    
Direct stock purchase plan (in shares)   47,422      
Direct stock purchase plan 7,231   7,231    
Retirement savings plan (in shares)   54,565      
Retirement savings plan 8,046   8,046    
1998 Long-term incentive plan (in shares)   276,263      
1998 Long-term incentive plan 2,685 $ 2 2,683    
Employee stock-based compensation $ 30,504   30,504    
Common stock shares outstanding, ending balance (in shares) at Sep. 30, 2025 161,568,384 161,568,384      
Shareholders' equity, ending balance at Sep. 30, 2025 $ 13,558,890 $ 808 $ 8,221,455 $ 475,015 $ 4,861,612
v3.25.3
CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Statement of Stockholders' Equity [Abstract]      
Cash dividends per share (USD per share) $ 3.48 $ 3.22 $ 2.96
v3.25.3
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
CASH FLOWS FROM OPERATING ACTIVITIES      
Net income $ 1,198,754 $ 1,042,895 $ 885,862
Adjustments to reconcile net income to net cash provided by operating activities:      
Depreciation and amortization 734,745 669,972 604,327
Deferred income taxes 268,606 172,707 108,215
Stock-based compensation 12,731 10,709 10,178
Amortization of debt issuance costs (14,962) (6,882) 3,639
Equity component of AFUDC (75,425) (58,234) (64,019)
Other 11,003 1,546 (591)
Changes in assets and liabilities:      
(Increase) decrease in accounts receivable (1,417) (40,909) 46,859
(Increase) decrease in gas stored underground (2,248) 76,322 112,111
Decrease in Winter Storm Uri current regulatory asset (see Note 10) 0 0 2,021,889
(Increase) decrease in other current assets 19,517 17,138 (36,041)
Increase in deferred charges and other assets (211,286) (195,369) (172,586)
Increase (decrease) in accounts payable and accrued liabilities 31,558 (4,563) (132,575)
Increase (decrease) in other current liabilities 31,406 (10,287) 30,687
Increase in deferred credits and other liabilities 46,474 58,701 41,788
Net cash provided by operating activities 2,049,456 1,733,746 3,459,743
CASH FLOWS USED IN INVESTING ACTIVITIES      
Capital expenditures (3,561,399) (2,937,124) (2,805,973)
Purchases of debt and equity securities (34,323) (19,734) (46,789)
Proceeds from sale of debt and equity securities 7,267 5,977 25,134
Maturities of debt securities 22,801 12,050 13,340
Other, net 4,372 16,062 19,008
Net cash used in investing activities (3,561,282) (2,922,769) (2,795,280)
CASH FLOWS FROM FINANCING ACTIVITIES      
Net increase (decrease) in short-term debt 0 (241,933) 56,966
Proceeds from issuance of long-term debt, net of premium/discount 1,143,447 1,240,204 797,258
Proceeds from issuance of securitized long-term debt by AEK 0 0 95,000
Net proceeds from equity offering 698,462 749,987 806,949
Issuance of common stock through stock purchase and employee retirement plans 15,277 15,084 15,395
Settlement of interest rate swaps 122,874 231,138 171,145
Proceeds from term loan 0 0 2,020,000
Repayment of term loan 0 0 (2,020,000)
Repayment of long-term debt 0 0 (2,200,000)
Repayment of securitized long-term debt by AEK (8,075) (9,922) 0
Cash dividends paid (553,761) (492,950) (430,345)
Debt issuance costs (10,384) (11,844) (7,864)
Securitized debt issuance costs 0 0 (1,273)
Other (1,067) (1,133) 0
Net cash provided by (used in) financing activities 1,406,773 1,478,631 (696,769)
Net increase (decrease) in cash and cash equivalents and restricted cash and cash equivalents (105,053) 289,608 (32,306)
Cash and cash equivalents and restricted cash and cash equivalents at beginning of year 308,856 19,248 51,554
Cash and cash equivalents and restricted cash and cash equivalents at end of year $ 203,803 $ 308,856 $ 19,248
v3.25.3
Nature of Business
12 Months Ended
Sep. 30, 2025
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. Through our distribution business, we deliver 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 in the service areas described below:
Division  Service Area
Atmos Energy Colorado-Kansas Division  Colorado, Kansas
Atmos Energy Kentucky/Mid-States Division  Kentucky, Tennessee, Virginia
Atmos Energy Louisiana Division  Louisiana
Atmos Energy Mid-Tex Division  Texas, including the Dallas/Fort Worth metropolitan area
Atmos Energy Mississippi Division  Mississippi
Atmos Energy West Texas Division  West Texas
 
In addition, we transport natural gas for others through our distribution system. Our distribution business is subject to federal and state regulation and/or regulation by local authorities in each of the states in which our distribution divisions operate. Our corporate headquarters and shared-services function are located in Dallas, Texas, and our customer support centers are located in Amarillo and Waco, Texas.
Our pipeline and storage business, which is also subject to federal and state regulation, consists of the pipeline and storage operations of our Atmos Pipeline–Texas (APT) Division and our natural gas transmission business in Louisiana. The APT division provides transportation and storage services to our Mid-Tex Division, other third-party local distribution companies, industrial, and electric generation customers, as well as marketers and producers. As part of its pipeline operations, APT manages five underground storage facilities in Texas. We also provide ancillary services customary to the pipeline industry including parking arrangements, lending, and sales of inventory on hand. Our natural gas transmission operations in Louisiana are comprised of a 21-mile pipeline located in the New Orleans, Louisiana area that is primarily used to aggregate gas supply for our distribution division in Louisiana under a long-term contract and on a more limited basis, to third parties.
v3.25.3
Summary of Significant Accounting Policies
12 Months Ended
Sep. 30, 2025
Accounting Policies [Abstract]  
Summary of Significant Accounting Policies Summary of Significant Accounting Policies
Principles of consolidation — The accompanying consolidated financial statements include the accounts of Atmos Energy Corporation and its wholly-owned subsidiaries. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process.
Reclassification — Certain reclassifications have been made to prior period amounts to conform to current period presentation.
Use of estimates — The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses. The most significant estimates include the allowance for doubtful accounts, unbilled revenues, contingency accruals, pension and postretirement obligations, deferred income taxes, risk management and trading activities, and fair value measurements. Actual results could differ from those estimates.
Regulation — Our distribution and pipeline and storage operations are subject to regulation with respect to rates, service, maintenance of accounting records, and various other matters by the respective regulatory authorities in the states in which we operate. Our accounting policies recognize the financial effects of the ratemaking and accounting practices and policies of the various regulatory commissions. 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. The amounts to be recovered or recognized are based upon historical experience and our understanding of the regulations. Further, regulation may impact the period in which revenues or expenses are recognized.
Revenue recognition
Distribution Revenues
Distribution revenues represent the delivery of natural gas to residential, commercial, industrial, and public authority customers at prices based on tariff rates established by regulatory authorities in the states in which we operate. Revenue is recognized and our performance obligation is satisfied over time when natural gas is delivered and simultaneously consumed by our customers. We have elected to use the invoice practical expedient and recognize revenue for volumes delivered that we have the right to invoice our customers. We bill our customers on a monthly cycle basis. Accordingly, we estimate volumes from the last meter read to the balance sheet date and accrue revenue for gas delivered but not yet billed.
In our Texas and Mississippi jurisdictions, we pay franchise fees and gross receipt taxes to operate in these service areas. These franchise fees and gross receipts taxes are required to be paid regardless of our ability to collect from our customers. Accordingly, we account for these amounts on a gross basis in revenue and we record the associated tax expense as a component of taxes, other than income.
Pipeline and Storage Revenues
Pipeline and storage revenues primarily represent the transportation and storage of natural gas on our APT system and the transmission of natural gas through our 21-mile pipeline in Louisiana. APT provides transportation and storage services to our Mid-Tex Division, other third party local distribution companies, and certain industrial customers under tariff rates approved by the RRC. APT also provides certain transportation and storage services to industrial and electric generation customers, as well as marketers and producers, under negotiated rates. Our pipeline in Louisiana is primarily used to aggregate gas supply for our Louisiana Division under a long-term contract and on a more limited basis to third parties. The demand fee charged to our Louisiana Division is subject to regulatory approval by the Louisiana Public Service Commission. We also manage two asset management plans with distribution affiliates of the Company at terms that have been approved by the applicable state regulatory commissions. The performance obligations for these transportation customers are satisfied by means of transporting customer-supplied gas to the designated location. Revenue is recognized and our performance obligation is satisfied over time when natural gas is delivered to the customer. Management determined that these arrangements qualify for the invoice practical expedient for recognizing revenue. For demand fee arrangements, revenue is recognized and our performance obligation is satisfied by standing ready to transport natural gas over the period of each individual month.
Alternative Revenue Program Revenues
In our distribution segment, we have weather-normalization adjustment mechanisms that serve to minimize the effects of weather on our residential and commercial revenues. APT has a regulatory mechanism that requires that we share with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a revenue benchmark established by the RRC. With the completion of APT's most recent rate case in December 2023, the revenue benchmark was increased from $69.4 million to $106.9 million. Differences between actual revenues and revenues calculated under these mechanisms adjust the amount billed to customers. These mechanisms are considered to be alternative revenue programs under accounting standards generally accepted in the United States as they are deemed to be contracts between us and our regulator. Accordingly, revenue under these mechanisms are excluded from revenue from contracts with customers.
Purchased gas costs — Rates established by regulatory authorities are adjusted for increases and decreases in our purchased gas costs through purchased gas cost adjustment mechanisms. There is no margin generated through purchased gas cost adjustments, but they provide a dollar-for-dollar offset to increases or decreases in our distribution segment’s gas costs. The effects of these purchased gas cost adjustment mechanisms are recorded as deferred gas costs on our consolidated balance sheets.
Cash and cash equivalents — We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents.
Restricted cash and cash equivalents — Restricted cash and cash equivalents consists of funds that are contractually or legally restricted as to usage or withdrawal and have been presented separately from cash and cash equivalents on our consolidated balance sheets. These funds are used to administer payment of debt service on the Securitized Utility Tariff Bonds as well as certain ongoing costs of Atmos Energy Kansas Securitization I, LLC (AEK).
Accounts receivable and allowance for uncollectible accounts — Accounts receivable arise from natural gas sales to residential, commercial, industrial, public authority, and other customers. Our accounts receivable balance includes unbilled amounts which represent a customer’s consumption of gas from the date of the last cycle billing through the last day of the month. The receivable balances are short term and generally do not extend beyond one month.
Credit losses on our accounts receivable are measured using an expected credit loss model over the entire contractual term from the date of initial recognition. To minimize credit risk, we assess the credit worthiness of new customers, require deposits where necessary, assess late fees, pursue collection activities, and disconnect service for nonpayment. After disconnection, accounts are written off when deemed uncollectible. At each reporting period, we assess the allowance for uncollectible accounts based on historical experience, current conditions, and consideration of expected future conditions. Circumstances which could affect our estimates include, but are not limited to, customer credit issues, the level of natural gas prices, customer deposits, and general economic conditions.
Gas stored underground — Our gas stored underground is comprised of natural gas injected into storage to support the winter season withdrawals for our distribution operations. The average cost method is used for all of our distribution operations. Gas in storage that is retained as cushion gas to maintain reservoir pressure is classified as property, plant and equipment and is valued at cost.
Securitized intangible asset — Our securitized intangible asset is recorded on AEK and represents the Securitized Utility Tariff Property acquired from Atmos Energy in fiscal 2023. See Note 10 to the consolidated financial statements. The securitized intangible asset is stated at cost, net of accumulated amortization, and is amortized over the life of the asset in proportion to the pattern of economic benefit based on expected future undiscounted cash flows. At the end of its life, this securitized intangible asset will have no residual value.
Property, plant and equipment — Regulated property, plant and equipment is stated at original cost, net of contributions in aid of construction. The cost of additions includes direct construction costs, payroll related costs (taxes, the service cost portion of pension expense and other benefits), administrative and general costs, and an allowance for funds used during construction (AFUDC). AFUDC represents the capitalizable total cost of funds used to finance the construction of major projects.
The following table details amounts capitalized for the fiscal year ended September 30.
202520242023
Component of AFUDCStatement of Comprehensive Income Location(In thousands)
DebtInterest charges$21,104 $14,655 $15,808 
EquityOther non-operating income75,425 58,234 64,019 
$96,529 $72,889 $79,827 
Major renewals, including replacement pipe, and betterments that are recoverable through our regulatory rate base are capitalized while the costs of maintenance and repairs that are not capitalizable are charged to expense as incurred. The costs of large projects are accumulated in construction in progress until the project is completed. When the project is completed, tested, and placed in service, the balance is transferred to the regulated plant in service account included in the rate base and depreciation begins.
Regulated property, plant and equipment is depreciated at various rates on a straight-line basis. These rates are approved by our regulatory commissions and are comprised of two components: one based on average service life and one based on cost of removal. Accordingly, we recognize our cost of removal expense as a component of depreciation expense. The related cost of removal accrual is reflected as a regulatory liability on the consolidated balance sheet. At the time property, plant and equipment is retired, removal expenses less salvage, are charged to the regulatory cost of removal accrual. The composite depreciation rate was 2.8 percent for the fiscal year ended September 30, 2025, 2.9 percent for the fiscal year ended September 30, 2024, and 3.0 percent for the fiscal year ended September 30, 2023.
Other property, plant and equipment is stated at cost. Depreciation is generally computed on the straight-line method for financial reporting purposes based upon estimated useful lives.
Impairment of long-lived assets — We evaluate whether events or circumstances have occurred that indicate that other long-lived assets may not be recoverable or that the remaining useful life may warrant revision. When such events or circumstances are present, we assess the recoverability of long-lived assets by determining whether the carrying value will be recovered through the expected future cash flows. In the event the sum of the expected future cash flows resulting from the use of the asset is less than the carrying value of the asset, an impairment loss equal to the excess of the asset’s carrying value over its fair value is recorded. No impairment losses were recorded for our long-lived assets during the fiscal years ended September 30, 2025, 2024, and 2023.
Goodwill — We annually evaluate our goodwill balances for impairment during our second fiscal quarter or more frequently as impairment indicators arise. During the second quarter of fiscal 2025, we completed our annual goodwill
impairment assessment. We test goodwill for 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. Although not applicable for the fiscal 2025 analysis, if a qualitative goodwill assessment resulted in impairment indicators, we would then use a present value technique based on discounted cash flows to estimate the fair value of our reporting units. These calculations are dependent on several subjective factors including the timing of future cash flows, future growth rates, and the discount rate. An impairment charge is recognized if the carrying value of a reporting unit’s goodwill exceeds its fair value.
Lease accounting — We determine if an arrangement is a lease at the inception of the agreement based on the terms and conditions in the contract. A contract contains a lease if there is an identified asset and we have the right to control the asset. We are the lessee for substantially all of our leasing activities, which primarily includes operating leases for office and warehouse space, tower space, vehicles, and heavy equipment used in our operations. We are also a lessee in finance leases for certain service centers.
We record a lease liability and a corresponding right of use (ROU) asset for all of our leases with a term greater than 12 months. For lease contracts containing renewal and termination options, we include the option period in the lease term when it is reasonably certain the option will be exercised. We most frequently assume renewal options at the inception of the arrangement for our tower and fleet leases, based on our anticipated use of the assets. Real estate leases that contain a renewal option are evaluated on a lease-by-lease basis to determine if the option period should be included in the lease term. Currently, we have not included material renewal options for real estate leases in our ROU asset or lease liability.
The lease liability represents the present value of all lease payments over the lease term. We do not include short-term leases in the calculation of our lease liabilities. The discount rate used to determine the present value of the lease liability is the rate implicit in the lease unless that rate cannot be readily determined. We use the implicit rate stated in the agreement to determine the lease liability for our fleet leases. We use our corporate collateralized incremental borrowing rate as the discount rate for all other lease agreements. This rate is appropriate because we believe it represents the rate we would have incurred to borrow funds to acquire the leased asset over a similar term. We calculated this rate using a combination of inputs, including our current credit rating, quoted market prices of interest rates for our publicly traded unsecured debt, observable market yield curve data for peer companies with a credit rating one notch higher than our current credit rating, and the lease term.
The ROU asset represents the right to use the underlying asset for the lease term, and is equal to the lease liability, adjusted for prepaid or accrued lease payments and any lease incentives that have been paid to us or when we are reasonably certain to incur costs equal to or greater than the allowance defined in the contract. We bundle our lease and non-lease components as a single component for all asset classes.
Variable payments included in our leasing arrangements are expensed in the period in which the obligation for these payments is incurred. Variable payments are dependent on usage, output or may vary for other reasons. Most of our variable lease expense is related to tower leases that have escalating payments based on changes to a stated CPI index, and usage of certain office equipment.
We have not provided material residual value guarantees for our leases, nor do our leases contain material restrictions or covenants.
Marketable securities — As of September 30, 2025, we hold marketable securities classified as either equity or debt securities. Changes in fair value of our equity securities are recorded in net income, while debt securities, which are considered available-for-sale securities, are reported at market value with unrealized gains and losses shown as a component of accumulated other comprehensive income (loss).
We regularly evaluate the performance of our available-for-sale debt securities on an investment by investment basis for impairment, taking into consideration the securities’ purpose, volatility, and current returns. If a determination is made that a security will likely be sold before the recovery of its cost, the related investment is written down to its estimated fair value.
Financial instruments and hedging activities — We use financial instruments to mitigate commodity price risk in our distribution and pipeline and storage segments and to mitigate interest rate risk. The objectives and strategies for using financial instruments have been tailored to our business and are discussed in Note 16 to the consolidated financial statements.
We record all of our financial instruments on the balance sheet at fair value, with the exception of normal purchases and normal sales that are expected to result in physical delivery, with changes in fair value ultimately recorded in the statement of comprehensive income. These financial instruments are reported as risk management assets and liabilities and are classified as current or noncurrent other assets or liabilities based upon the anticipated settlement date of the underlying financial instrument. We record the cash flow impact of our financial instruments in operating cash flows based upon their balance sheet classification.
The timing of when changes in fair value of our financial instruments are recorded in the statement of comprehensive income depends on whether the financial instrument has been designated and qualifies as a part of a hedging relationship or if regulatory rulings require a different accounting treatment. Changes in fair value for financial instruments that do not meet one of these criteria are recognized in the statement of comprehensive income as they occur.
Financial Instruments Associated with Commodity Price Risk
In our distribution segment, the costs associated with and the realized gains and losses arising from the use of financial instruments to mitigate commodity price risk are included in our purchased gas cost adjustment mechanisms in accordance with regulatory requirements. Therefore, changes in the fair value of these financial instruments are initially recorded as a component of deferred gas costs and recognized in the consolidated statements of comprehensive income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue in accordance with accounting principles generally accepted in the United States. Accordingly, there is no earnings impact on our distribution segment as a result of the use of these financial instruments.
Financial Instruments Associated with Interest Rate Risk
In connection with the planned issuance of long-term debt, we may use financial instruments to manage interest rate risk. We currently manage this risk through the use of forward starting interest rate swaps to fix the Treasury yield component of the interest cost associated with anticipated financings. We designate these financial instruments as cash flow hedges at the time the agreements are executed. Unrealized gains and losses associated with the instruments are recorded as a component of accumulated other comprehensive income (loss). When the instruments settle, the realized gain or loss is recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest charges over the life of the related financing arrangement. As of September 30, 2025 and 2024, no cash was required to be held in margin accounts.
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 primarily use quoted market prices and other observable market pricing information in valuing our financial assets and liabilities and minimize the use of unobservable pricing inputs in our measurements.
Fair-value estimates also consider our own creditworthiness and the creditworthiness of the counterparties involved. Our counterparties consist primarily of financial institutions and major energy companies. This concentration of counterparties may materially impact our exposure to credit risk resulting from market, economic, or regulatory conditions. We seek to minimize counterparty credit risk through an evaluation of their financial condition and credit ratings and the use of collateral requirements under certain circumstances.
Amounts reported at fair value are subject to potentially significant volatility based upon changes in market prices, including, but not limited to, the valuation of the portfolio of our contracts, maturity, and settlement of these contracts and newly originated transactions and interest rates, each of which directly affect the estimated fair value of our financial instruments. We believe the market prices and models used to value these financial instruments represent the best information available with respect to closing exchange and over-the-counter quotations, time value, and volatility factors underlying the contracts. Values are adjusted to reflect the potential impact of an orderly liquidation of our positions over a reasonable period of time under then current market conditions.
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) and the lowest priority given to unobservable inputs (Level 3). The levels of the hierarchy are described below:
Level 1 — Represents unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is defined as a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Prices actively quoted on national exchanges are used to determine the fair value of most of our assets and liabilities recorded on our balance sheet at fair value.
Our Level 1 measurements consist primarily of our debt and equity securities. The Level 1 measurements for investments in the Atmos Energy Corporation Master Retirement Trust (the Master Trust), Supplemental Executive Benefit Plan, and postretirement benefit plan consist primarily of exchange-traded financial instruments.
Level 2 — Represents pricing inputs other than quoted prices included in Level 1 that are either directly or indirectly observable for the asset or liability as of the reporting date. These inputs are derived principally from, or corroborated by, observable market data. Our Level 2 measurements primarily consist of non-exchange-traded financial instruments, such as over-the-counter options and swaps and municipal and corporate bonds where market data for pricing is observable. The Level
2 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan, and postretirement benefit plan consist primarily of non-exchange traded financial instruments such as corporate bonds and government securities.
Level 3 — Represents generally unobservable pricing inputs which are developed based on the best information available, including our own internal data, in situations where there is little if any market activity for the asset or liability at the measurement date. The pricing inputs utilized reflect what a market participant would use to determine fair value. We currently do not have any Level 3 investments.
Pension and other postretirement plans — Pension and other postretirement plan costs and liabilities are determined on an actuarial basis and are affected by numerous assumptions and estimates including the market value of plan assets, estimates of the expected return on plan assets, assumed discount rates, and current demographic and actuarial mortality data. Our measurement date is September 30. The assumed discount rate and the expected return are the assumptions that generally have the most significant impact on our pension costs and liabilities. The assumed discount rate, the assumed health care cost trend rate, and assumed rates of retirement generally have the most significant impact on our postretirement plan costs and liabilities.
The discount rate is utilized principally in calculating the actuarial present value of our pension and postretirement obligation and net pension and postretirement cost. When establishing our discount rate, we consider high quality corporate bond rates based on bonds available in the marketplace that are suitable for settling the obligations, changes in those rates from the prior year, and the implied discount rate that is derived from matching our projected benefit disbursements with currently available high quality corporate bonds.
The expected long-term rate of return on assets is utilized in calculating the expected return on plan assets component of the annual pension and postretirement plan cost. We estimate the expected return on plan assets by evaluating expected bond returns, equity risk premiums, asset allocations, the effects of active plan management, the impact of periodic plan asset rebalancing, and historical performance. We also consider the guidance from our investment advisors when making a final determination of our expected rate of return on assets. To the extent the actual rate of return on assets realized over the course of a year is greater than or less than the assumed rate, that year’s annual pension or postretirement plan cost is not affected. Rather, this gain or loss is amortized over the expected future working lifetime of the plan participants.
The expected return on plan assets is then calculated by applying the expected long-term rate of return on plan assets to the market-related value of the plan assets. The market-related value of our plan assets represents the fair market value of the plan assets, adjusted to smooth out short-term market fluctuations over a five-year period. The use of this calculation will delay the impact of current market fluctuations on the pension expense for the period.
We use a corridor approach to amortize actuarial gains and losses. Under this approach, net gains or losses in excess of ten percent of the larger of the pension benefit obligation or the market-related value of the assets are amortized on a straight-line basis. The period of amortization is the average remaining service of active participants who are expected to receive benefits under the plan.
We estimate the assumed health care cost trend rate used in determining our annual postretirement net cost based upon our actual health care cost experience, the effects of recently enacted legislation, and general economic conditions. Our assumed rate of retirement is estimated based upon the annual review of our participant census information as of the measurement date.
We present only the current service cost component of the net benefit cost within operations and maintenance expense in the consolidated statements of comprehensive income. The remaining components of net benefit cost are recorded in other non-operating income (expense) in our consolidated statements of comprehensive income. Only the service cost component of net benefit cost is eligible for capitalization and we continue to capitalize these costs into property, plant and equipment. Additionally, we defer into a regulatory asset or liability the portion of non-service components of net periodic benefit cost that are capitalizable for regulatory purposes.
Income taxes — Income taxes are determined based on the liability method, which results in income tax assets and liabilities arising from temporary differences. Temporary differences are differences between the tax bases of assets and liabilities and their reported amounts in the financial statements that will result in taxable or deductible amounts in future years. The liability method requires the effect of tax rate changes on accumulated deferred income taxes to be reflected in the period in which the rate change was enacted. The liability method also requires that deferred tax assets be reduced by a valuation allowance unless it is more likely than not that the assets will be realized.
The Company may recognize the tax benefit from uncertain tax positions only if it is at least more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon settlement with the taxing authorities. We recognize accrued interest
related to unrecognized tax benefits as a component of interest charges. We recognize penalties related to unrecognized tax benefits as a component of miscellaneous income (expense) in accordance with regulatory requirements.
Tax collections — We are allowed to recover from customers revenue-related taxes that are imposed upon us. We record such taxes as operating expenses and record the corresponding customer charges as operating revenues. However, we do collect and remit various other taxes on behalf of various governmental authorities, and we record these amounts in our consolidated balance sheets on a net basis. We do not collect income taxes from our customers on behalf of governmental authorities.
Contingencies — In the normal course of business, we are confronted with issues or events that may result in a contingent liability. These generally relate to lawsuits, claims made by third parties, or the action of various regulatory agencies. For such matters, we record liabilities when they are considered probable and estimable, based on currently available facts and our estimates of the ultimate outcome or resolution of the liability in the future. We maintain liability insurance for various risks associated with the operation of our natural gas pipelines and facilities, including for property damage and bodily injury. These liability insurance policies generally require us to be responsible for the first $1.0 million (self-insured retention) of each incident. To the extent a loss contingency exceeds the self-insurance retention, we record an insurance receivable when recovery is considered probable. Upon reaching a settlement, the loss contingency is deemed resolved and recorded in accounts payable and accrued liabilities until paid. Loss contingencies and any related insurance recovery receivables reflect our best estimate of these amounts as of the date of this report. Actual results may differ from estimates, depending on actual outcomes or changes in the facts or expectations surrounding each potential exposure.
We record a liability at fair value for an asset retirement obligation when the legal obligation to retire the asset has been incurred with an offsetting increase to the carrying value of the related asset. We believe we have a legal obligation to retire our natural gas storage facilities. However, we have not recognized an asset retirement obligation associated with our storage facilities because we are not able to determine the settlement date of this obligation as we do not anticipate taking our storage facilities out of service permanently. Therefore, we cannot reasonably estimate the fair value of this obligation.
Subsequent events — Except as noted in Note 7 and Note 8 to the consolidated financial statements regarding the execution of a new lease and the public offering of senior notes, no events occurred subsequent to the balance sheet date that would require recognition or disclosure in the consolidated financial statements.
Recent accounting pronouncements
Accounting pronouncements adopted in fiscal 2025
In November 2023, the Financial Accounting Standards Board (FASB) issued guidance which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. We adopted this amendment as of September 30, 2025 and applied it retrospectively for all periods presented. See Note 4 for further discussion.
In December 2023, the FASB issued guidance which provides qualitative and quantitative updates to the rate reconciliation and income taxes paid disclosures, among others, in order to enhance the transparency of income tax disclosures, including consistent categories and greater disaggregation of information in the rate reconciliation and disaggregation by jurisdiction of income taxes paid. We early adopted this amendment as of September 30, 2025 and applied it retrospectively for all periods presented. See Note 15 for further discussion.
Accounting pronouncements that will be effective after fiscal 2025
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 reporting periods 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.
v3.25.3
Regulation
12 Months Ended
Sep. 30, 2025
Regulated Operations [Abstract]  
Regulation Regulation
Our distribution and pipeline and storage operations are subject to regulation with respect to rates, service, maintenance of accounting records, and various other matters by the respective regulatory authorities in the states in which we operate, which creates regulatory assets and liabilities that are recovered from or refunded to customers over time 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 and the long-term portion of regulatory excess deferred taxes and regulatory cost of removal obligation are reported separately. Significant regulatory assets and liabilities as of September 30, 2025 and 2024 included the following:
 September 30
 20252024
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$262 $11,243 
Infrastructure mechanisms (1)
314,047 246,734 
Winter Storm Uri incremental costs5,841 10,373 
Deferred gas costs140,626 159,762 
Regulatory excess deferred taxes (2)
49,793 51,380 
Recoverable loss on reacquired debt2,903 3,070 
Deferred pipeline record collection costs39,035 41,742 
System Safety and Integrity Riders (3)
43,625 38,632 
Other12,597 16,454 
$608,729 $579,390 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$190,274 $257,001 
Regulatory cost of removal obligation641,019 607,032 
Deferred gas costs6,879 9,142 
APT annual adjustment mechanism99,393 73,119 
Pension and postretirement benefit costs291,351 247,250 
Other40,732 34,338 
$1,269,648 $1,227,882 

(1)Infrastructure mechanisms in Texas, Louisiana, and Tennessee allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered 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 Notes 13 and 15 to the 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.
v3.25.3
Segment Information
12 Months Ended
Sep. 30, 2025
Segment Reporting [Abstract]  
Segment Information Segment Information
As of September 30, 2025, we manage and review our consolidated operations through the following two 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.
Our determination of reportable segments considers the strategic operating units under which we manage sales of various products and services to customers. Although our distribution segment operations are geographically dispersed, they are aggregated and reported as a single segment as each natural gas distribution division has similar economic characteristics. In
addition, because the pipeline and storage operations of our Atmos Pipeline-Texas division and our natural gas transmission operations in Louisiana have similar economic characteristics, they have been aggregated and reported as a single segment.
The accounting policies of the segments are the same as those described in the summary of significant accounting policies. We evaluate performance based on net income or loss of the respective operating units. We allocate interest and pension expense to the pipeline and storage segment; however, there is no debt or pension liability recorded on the pipeline and storage segment balance sheet. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process. Income taxes are allocated to each segment as if each segment’s income taxes were calculated on a separate return basis.
Our Chief Operating Decision Maker (CODM), the Chief Executive Officer, evaluates performance for each reportable segment based on net income, which is used to help inform the allocation of resources as part of the Company's process for budgeting and monitoring financial performance.
Income statement information and capital expenditures by segment are shown in the following tables.
 Year Ended September 30, 2025
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Operating revenues from external parties$4,422,355 $280,400 $4,702,755 
Intersegment revenues3,042 784,900 787,942 
Total operating revenues4,425,397 1,065,300 5,490,697 
Operation and maintenance expense644,924 229,986 874,910 
Depreciation and amortization expense (2)
543,840 190,905 734,745 
Interest charges (2)
99,226 72,452 171,678 
Income tax expense (2)
150,961 128,319 279,280 
Other segment items (1)
2,239,665 (8,335)2,231,330 
Net income (2)
$746,781 $451,973 $1,198,754 
Capital expenditures (2)
$2,662,703 $898,696 $3,561,399 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$5,490,697 
Elimination of intersegment revenues(787,942)
Consolidated total operating revenues$4,702,755 
 Year Ended September 30, 2024
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Operating revenues from external parties$3,912,134 $253,053 $4,165,187 
Intersegment revenues3,007 684,976 687,983 
Total operating revenues3,915,141 938,029 4,853,170 
Operation and maintenance expense589,864 218,571 808,435 
Depreciation and amortization expense (2)
491,982 177,990 669,972 
Interest charges (2)
117,086 73,546 190,632 
Income tax expense (2)
96,041 96,840 192,881 
Other segment items (1)
1,948,755 (400)1,948,355 
Net income (2)
$671,413 $371,482 $1,042,895 
Capital expenditures (2)
$2,249,280 $687,844 $2,937,124 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,853,170 
Elimination of intersegment revenues(687,983)
Consolidated total operating revenues$4,165,187 

 Year Ended September 30, 2023
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Operating revenues from external parties$4,096,661 $178,696 $4,275,357 
Intersegment revenues3,029 606,478 609,507 
Total operating revenues4,099,690 785,174 4,884,864 
Operation and maintenance expense543,078 200,580 743,658 
Depreciation and amortization expense (2)
434,721 169,606 604,327 
Interest charges (2)
77,185 60,096 137,281 
Income tax expense (2)
60,032 53,747 113,779 
Other segment items (1)
2,404,277 (4,320)2,399,957 
Net income (2)
$580,397 $305,465 $885,862 
Capital expenditures (2)
$1,927,125 $878,848 $2,805,973 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,884,864 
Elimination of intersegment revenues(609,507)
Consolidated total operating revenues$4,275,357 
(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 reconcile to consolidated totals.
The following table summarizes our revenues from external parties, excluding intersegment revenues, by products and services for the fiscal years ended September 30.
202520242023
 (In thousands)
Distribution revenues:
Gas sales revenues:
Residential$2,916,245 $2,583,681 $2,638,689 
Commercial1,154,591 1,016,675 1,112,236 
Industrial122,576 100,596 151,970 
Public authority and other52,606 52,180 62,476 
Total gas sales revenues4,246,018 3,753,132 3,965,371 
Transportation revenues149,853 132,608 119,371 
Other gas revenues26,484 26,394 11,919 
Total distribution revenues4,422,355 3,912,134 4,096,661 
Pipeline and storage revenues280,400 253,053 178,696 
Total operating revenues$4,702,755 $4,165,187 $4,275,357 

Balance sheet information at September 30, 2025 and 2024 by segment is presented in the following tables.
 September 30, 2025
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Property, plant and equipment, net (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 

 September 30, 2024
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Property, plant and equipment, net (1)
$16,372,659 $5,831,708 $22,204,367 
Total assets$24,328,877 $6,181,558 $30,510,435 
Reconciliation to consolidated assets:
Total assets of reportable segments$30,510,435 
Elimination of intersegment assets(5,315,970)
Consolidated total assets$25,194,465 
(1)The total of reportable segments for this item reconciles to consolidated total.
v3.25.3
Earnings Per Share
12 Months Ended
Sep. 30, 2025
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 9 to the consolidated financial statements, when the impact is dilutive.
Basic and diluted earnings per share for the fiscal years ended September 30 are calculated as follows:
202520242023
 (In thousands, except per share data)
Basic Earnings Per Share
Net income$1,198,754 $1,042,895 $885,862 
Less: Income allocated to participating securities487 553 542 
Net income available to common shareholders$1,198,267 $1,042,342 $885,320 
Basic weighted average shares outstanding158,943 152,508 145,121 
Net income per share — Basic$7.54 $6.83 $6.10 
Diluted Earnings Per Share
Net income available to common shareholders$1,198,267 $1,042,342 $885,320 
Effect of dilutive shares— — — 
Net income available to common shareholders$1,198,267 $1,042,342 $885,320 
Basic weighted average shares outstanding158,943 152,508 145,121 
Dilutive shares1,630 158 45 
Diluted weighted average shares outstanding160,573 152,666 145,166 
Net income per share — Diluted$7.46 $6.83 $6.10 
v3.25.3
Revenue and Accounts Receivable
12 Months Ended
Sep. 30, 2025
Revenue from Contract with Customer [Abstract]  
Revenue and Accounts Receivable Revenue and Accounts Receivable
The following tables disaggregates our revenue from contracts with customers by customer type and segment and provides a reconciliation to total operating revenues, including intersegment revenues, for the periods presented.
Year Ended September 30, 2025
DistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$2,877,456 $— 
Commercial1,145,710 — 
Industrial122,284 — 
Public authority and other51,354 — 
Total gas sales revenues4,196,804 — 
Transportation revenues151,876 1,119,015 
Miscellaneous revenues13,123 12,749 
Revenues from contracts with customers4,361,803 1,131,764 
Alternative revenue program revenues49,215 (66,464)
Other revenues14,379 — 
Total operating revenues$4,425,397 $1,065,300 
Year Ended September 30, 2024
DistributionPipeline and Storage
Gas sales revenues:
Residential$2,542,438 $— 
Commercial1,006,593 — 
Industrial100,363 — 
Public authority and other51,337 — 
Total gas sales revenues3,700,731 — 
Transportation revenues134,600 982,795 
Miscellaneous revenues11,836 15,892 
Revenues from contracts with customers3,847,167 998,687 
Alternative revenue program revenues52,401 (60,658)
Other revenues15,573 — 
Total operating revenues$3,915,141 $938,029 
Year Ended September 30, 2023
DistributionPipeline and Storage
Gas sales revenues:
Residential$2,606,658 $— 
Commercial1,100,773 — 
Industrial151,538 — 
Public authority and other61,345 — 
Total gas sales revenues3,920,314 — 
Transportation revenues121,420 811,968 
Miscellaneous revenues10,044 12,180 
Revenues from contracts with customers4,051,778 824,148 
Alternative revenue program revenues43,139 (38,974)
Other revenues4,773 — 
Total operating revenues$4,099,690 $785,174 
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 10 to the consolidated financial statements) and other miscellaneous revenues.
Accounts receivable and allowance for uncollectible accounts
Rollforwards of our allowance for uncollectible accounts for the years ended September 30, 2025, 2024, and 2023 are presented in the table below.
We actively work with our customers experiencing financial hardship to offer flexible payment options and to direct them to aid agencies for financial assistance. Our allowance for uncollectible accounts reflects the expected impact on our customers’ ability to pay. Our allowance for uncollectible accounts also reflects the fact that we have the ability to recover the gas cost portion of uncollectible accounts through our gas cost recovery mechanisms in six states, which covers approximately 89 percent of our residential and commercial customers.
In December 2023, the Mississippi Public Service Commission approved the recovery of uncollectible accounts through our purchased gas cost mechanism over a two-year period rather than through our annual filing mechanism over a one-year period. As a result of this decision, we recorded a $13.9 million reduction to bad debt expense during the first quarter of fiscal
2024. Of this amount, $9.7 million represents future recovery of customer receivables previously written off since April 2022 but not yet recovered through our rates. This amount increased our deferred gas cost regulatory asset. The remaining $4.2 million reduction represents a reversal of our allowance for uncollectible accounts for customer balances that have not yet been written off.
 Allowance for uncollectible accounts
 (In thousands)
Balance, September 30, 2022
$49,993 
Current period provisions22,353 
Write-offs charged against allowance(33,595)
Recoveries of amounts previously written off2,089 
Balance, September 30, 2023
40,840 
Current period provisions24,843 
Write-offs charged against allowance(26,165)
Recoveries of amounts previously written off1,730 
Mississippi recovery of uncollectible accounts(4,192)
Balance, September 30, 2024
37,056 
Current period provisions30,778 
Write-offs charged against allowance(24,631)
Recoveries of amounts previously written off2,056 
Balance, September 30, 2025
$45,259 
v3.25.3
Leases
12 Months Ended
Sep. 30, 2025
Leases [Abstract]  
Leases Leases
We utilize operating leases for office and warehouse space, tower space, vehicles, and heavy equipment used in our operations. We also have finance leases for certain build-to-suit service centers.
The following table presents our weighted average remaining lease term for our leases.
September 30, 2025September 30, 2024
Weighted average remaining lease term (years)
Finance leases15.716.7
Operating leases8.89.9
The following table represents our weighted average discount rate:
September 30, 2025September 30, 2024
Weighted average discount rate
Finance leases4.0 %4.0 %
Operating leases4.5 %4.1 %
Lease costs for the years ended September 30, 2025, 2024, and 2023 are presented in the table below. These costs include both amounts recognized in expense and amounts capitalized. For the years ended September 30, 2025, 2024, and 2023 we did not have material short-term lease costs or variable lease costs.
Year Ended September 30
202520242023
(In thousands)
Finance lease cost$4,467 $4,523 $4,499 
Operating lease cost56,695 48,421 44,090 
Total lease cost$61,162 $52,944 $48,589 
Our ROU assets and lease liabilities are presented as follows on the consolidated balance sheets:
Balance Sheet ClassificationSeptember 30, 2025September 30, 2024
(In thousands)
Assets
Finance leasesNet property, plant and equipment$42,064 $44,748 
Operating leasesDeferred charges and other assets293,934 249,556 
Total right-of-use assets$335,998 $294,304 
Liabilities
Current
Finance leasesCurrent maturities of long-term debt$1,775 $1,651 
Operating leasesOther current liabilities45,010 34,340 
Noncurrent
Finance leasesLong-term debt45,459 47,239 
Operating leasesDeferred credits and other liabilities262,549 224,498 
Total lease liabilities$354,793 $307,728 
Three service center leases are expected to commence in fiscal 2026 that impact our future lease payments. The total future lease payments for these leases is $116.5 million. We also entered into one service center lease during the first quarter of fiscal 2026 that is expected to commence in fiscal 2027. The total future lease payments for this lease is $33.1 million. These amounts are not included in the tables below.
Other pertinent information related to leases was as follows. During the years ended September 30, 2025, 2024, and 2023 amounts paid in cash for our finance leases were not material.
Year Ended September 30
202520242023
(In thousands)
Cash paid amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases$52,528 $47,069 $45,463 
Right-of-use assets obtained in exchange for lease obligations
Finance leases$— $— $— 
Operating leases$89,598 $65,672 $29,976 
Maturities of our lease liabilities as of September 30, 2025 were as follows by fiscal years:
TotalFinance LeasesOperating Leases
(In thousands)
2026$60,048 $3,502 $56,546 
202755,881 3,568 52,313 
202850,775 3,635 47,140 
202944,304 3,703 40,601 
203038,240 3,782 34,458 
Thereafter189,621 44,877 144,744 
Total lease payments438,869 63,067 375,802 
Less: Imputed interest84,076 15,833 68,243 
Total$354,793 $47,234 $307,559 
Reported as of September 30, 2025
Short-term lease liabilities$46,785 $1,775 $45,010 
Long-term lease liabilities308,008 45,459 262,549 
Total lease liabilities$354,793 $47,234 $307,559 
Leases Leases
We utilize operating leases for office and warehouse space, tower space, vehicles, and heavy equipment used in our operations. We also have finance leases for certain build-to-suit service centers.
The following table presents our weighted average remaining lease term for our leases.
September 30, 2025September 30, 2024
Weighted average remaining lease term (years)
Finance leases15.716.7
Operating leases8.89.9
The following table represents our weighted average discount rate:
September 30, 2025September 30, 2024
Weighted average discount rate
Finance leases4.0 %4.0 %
Operating leases4.5 %4.1 %
Lease costs for the years ended September 30, 2025, 2024, and 2023 are presented in the table below. These costs include both amounts recognized in expense and amounts capitalized. For the years ended September 30, 2025, 2024, and 2023 we did not have material short-term lease costs or variable lease costs.
Year Ended September 30
202520242023
(In thousands)
Finance lease cost$4,467 $4,523 $4,499 
Operating lease cost56,695 48,421 44,090 
Total lease cost$61,162 $52,944 $48,589 
Our ROU assets and lease liabilities are presented as follows on the consolidated balance sheets:
Balance Sheet ClassificationSeptember 30, 2025September 30, 2024
(In thousands)
Assets
Finance leasesNet property, plant and equipment$42,064 $44,748 
Operating leasesDeferred charges and other assets293,934 249,556 
Total right-of-use assets$335,998 $294,304 
Liabilities
Current
Finance leasesCurrent maturities of long-term debt$1,775 $1,651 
Operating leasesOther current liabilities45,010 34,340 
Noncurrent
Finance leasesLong-term debt45,459 47,239 
Operating leasesDeferred credits and other liabilities262,549 224,498 
Total lease liabilities$354,793 $307,728 
Three service center leases are expected to commence in fiscal 2026 that impact our future lease payments. The total future lease payments for these leases is $116.5 million. We also entered into one service center lease during the first quarter of fiscal 2026 that is expected to commence in fiscal 2027. The total future lease payments for this lease is $33.1 million. These amounts are not included in the tables below.
Other pertinent information related to leases was as follows. During the years ended September 30, 2025, 2024, and 2023 amounts paid in cash for our finance leases were not material.
Year Ended September 30
202520242023
(In thousands)
Cash paid amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases$52,528 $47,069 $45,463 
Right-of-use assets obtained in exchange for lease obligations
Finance leases$— $— $— 
Operating leases$89,598 $65,672 $29,976 
Maturities of our lease liabilities as of September 30, 2025 were as follows by fiscal years:
TotalFinance LeasesOperating Leases
(In thousands)
2026$60,048 $3,502 $56,546 
202755,881 3,568 52,313 
202850,775 3,635 47,140 
202944,304 3,703 40,601 
203038,240 3,782 34,458 
Thereafter189,621 44,877 144,744 
Total lease payments438,869 63,067 375,802 
Less: Imputed interest84,076 15,833 68,243 
Total$354,793 $47,234 $307,559 
Reported as of September 30, 2025
Short-term lease liabilities$46,785 $1,775 $45,010 
Long-term lease liabilities308,008 45,459 262,549 
Total lease liabilities$354,793 $47,234 $307,559 
v3.25.3
Debt
12 Months Ended
Sep. 30, 2025
Debt Disclosure [Abstract]  
Debt Debt
Long-term debt
Long-term debt at September 30, 2025 and 2024 consisted of the following:
20252024
 (In thousands)
Unsecured 3.00% Senior Notes, due June 2027
$500,000 $500,000 
Unsecured 2.625% Senior Notes, due September 2029
500,000 500,000 
Unsecured 1.50% Senior Notes, due January 2031
600,000 600,000 
Unsecured 5.45% Senior Notes, due October 2032
300,000 300,000 
Unsecured 5.90% Senior Notes, due 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 — 
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 — 
Medium term Series A notes, 1995-1, 6.67%, due December 2025
10,000 10,000 
Unsecured 6.75% Debentures, due July 2028
150,000 150,000 
Finance lease obligations (see Note 7)
47,234 48,890 
Total long-term debt8,982,234 7,833,890 
Less:
Net original issue premium on unsecured senior notes and debentures(1,332)(9,071)
Debt issuance cost64,622 57,664 
Current maturities11,775 1,651 
$8,907,169 $7,783,646 
Maturities of long-term debt, excluding our finance lease obligations, at September 30, 2025 were as follows by fiscal years (in thousands):
2026$10,000 
2027500,000 
2028150,000 
2029500,000 
2030— 
Thereafter7,775,000 
$8,935,000 
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 estimated offering costs and settlement of our interest rate swaps. The net proceeds from the offering, after the underwriting discount and estimated offering expenses, of $589.8 million were used for general corporate purposes. In September 2025, we settled the designated interest rate swaps associated with the offering and received $122.9 million.
On June 26, 2025, we completed a public offering of $500 million of 5.20% senior notes due August 2035, with an effective interest rate of 5.35%, after giving effect to the offering costs. The net proceeds from the offering, after the underwriting discount and offering expenses, of $493.7 million were used for general corporate purposes.
On October 1, 2024, we completed a public offering of $650 million of 5.00% senior notes due December 2054, with an effective interest rate of 3.90%, 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 $639.4 million were used for general corporate purposes. In September 2024, we settled the designated interest rate swaps associated with this offering and received $231.1 million.
On June 21, 2024, we completed a public offering of $325 million of 5.90% senior notes due November 2033, with an effective interest rate of 5.17%, after giving effect to the offering costs. The net proceeds from the offering, after the underwriting discount and offering expenses, of $339.0 million were used for general corporate purposes.
On October 10, 2023, we completed a public offering of $500 million of 6.20% senior notes due November 2053, with an effective interest rate of 5.56%, after giving effect to the offering costs and settlement of our interest rate swaps, and $400 million of 5.90% senior notes due November 2033, with an effective interest rate of 4.35%, after giving effect to the offering costs and settlement of our interest rate swaps. The net proceeds from the offering, after the underwriting discount and offering expenses, of $889.4 million were used for general corporate purposes. In September 2023, we settled the designated interest rate swaps associated with this offering and received $171.1 million.
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 that expires on March 28, 2030. 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 September 30, 2025 and 2024, there were no amounts outstanding under our commercial paper program.
We also have a $1.5 billion three-year senior unsecured credit facility, which expires March 28, 2028, that is used to provide additional working capital funding. 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 September 30, 2025 and 2024, there were no borrowings outstanding under this facility.
Additionally, we have a $50 million 364-day unsecured facility, which was renewed April 1, 2025 and is used to provide working capital funding. There were no borrowings outstanding under this facility as of September 30, 2025 and 2024.
Finally, we have a $50 million 364-day unsecured revolving credit facility, which was renewed March 31, 2025 and is used to issue letters of credit and to provide working capital funding. At September 30, 2025, there were no borrowings outstanding under the new 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 September 30, 2025, our total-debt-to-total-capitalization ratio, as defined, was 41 percent. In addition, both the interest margin and the fee that we pay on unused amounts under each 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 is not paid at maturity. We were in compliance with all of our debt covenants as of September 30, 2025. 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.
v3.25.3
Shareholders' Equity
12 Months Ended
Sep. 30, 2025
Equity [Abstract]  
Shareholders' Equity Shareholders' Equity
Shelf Registration, At-the-Market Equity Sales Program and Equity Issuances
On December 3, 2024, we filed a shelf registration statement 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. This shelf registration statement replaced our previous shelf registration statement which was filed on March 31, 2023. As of the date of this report, $5.2 billion of securities remained available for issuance under the shelf registration statement.
On December 3, 2024, we filed a prospectus supplement under the shelf registration statement relating to an at-the-market (ATM) equity sales program under which we may issue and sell shares of our common stock up to an aggregate offering price of $1.7 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 year ended September 30, 2025, we executed forward sales under our ATM equity sales program with various forward sellers who borrowed and sold 5,967,768 shares of our common stock at an aggregate price of $871.5 million. During the year ended September 30, 2025, we also settled forward sale agreements with respect to 5,931,289 shares that had been borrowed and sold by various forward sellers under the ATM program for net proceeds of $698.5 million. As of September 30, 2025, $828.5 million of equity was available for issuance under our existing ATM program. Additionally, we had $1.6 billion in available proceeds from outstanding forward sale agreements, as detailed below.
MaturityShares AvailableNet Proceeds Available
(In Thousands)
Forward Price
December 31, 20251,160,351$148,610 $128.07 
March 31, 20263,627,033465,210 $128.26 
June 30, 2026669,04389,572 $133.88 
December 31, 20263,392,352475,294 $140.11 
March 31, 20272,477,820379,836 $153.29 
Total11,326,599$1,558,522 $137.60 
Accumulated Other Comprehensive Income (Loss)
We record deferred gains (losses) in accumulated other comprehensive income (AOCI) related to available-for-sale debt securities and interest rate agreement cash flow hedges. Deferred gains (losses) for our available-for-sale debt securities are recognized in earnings upon settlement, while deferred gains (losses) related to our interest rate agreement cash flow hedges are recognized in earnings as a component of interest charges, as they are amortized. The following tables provide the components of our accumulated other comprehensive income (loss) balances, net of the related tax effects allocated to each component of other comprehensive income (loss).
Available-
for-Sale
Securities
Interest Rate
Agreement
Cash Flow
Hedges
Total
 (In thousands)
September 30, 2024$213 $465,502 $465,715 
Other comprehensive income (loss) before reclassifications(4)24,208 24,204 
Amounts reclassified from accumulated other comprehensive income— (14,904)(14,904)
Net current-period other comprehensive income (loss)(4)9,304 9,300 
September 30, 2025$209 $474,806 $475,015 
 
Available-
for-Sale
Securities
Interest Rate
Agreement
Cash Flow
Hedges
Total
 (In thousands)
September 30, 2023$(369)$518,897 $518,528 
Other comprehensive income (loss) before reclassifications582 (43,430)(42,848)
Amounts reclassified from accumulated other comprehensive income
— (9,965)(9,965)
Net current-period other comprehensive income (loss)582 (53,395)(52,813)
September 30, 2024$213 $465,502 $465,715 
v3.25.3
Securitization
12 Months Ended
Sep. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Securitization Securitization
Kansas
In 2021, the Kansas State Legislature enacted securitization legislation, which permitted a natural gas public utility, in its sole discretion, to apply to the Kansas Corporation Commission (KCC) for a financing order for the recovery of qualified extraordinary costs through the issuance of bonds. In September 2021, we filed with the KCC an application to securitize extraordinary gas costs incurred during Winter Storm Uri, which was approved in October 2022.
Atmos Energy Kansas Securitization I, LLC (AEK), a special-purpose entity wholly owned by Atmos Energy, was formed for the purpose of issuing securitized bonds to recover extraordinary costs incurred during Winter Storm Uri. In June 2023, AEK completed a public offering of $95 million of 5.155% Series 2023-A Senior Secured Securitized Utility Tariff Bonds with a term of 10 years and semi-annual payments of principal and interest. The net proceeds from the offering, after the underwriting discount and offering expenses, of $93.7 million were primarily used to purchase the Securitized Utility Tariff Property from Atmos Energy for $92.3 million. The bonds are governed by an indenture between AEK and the indenture trustee. The indenture contains certain covenants that restrict AEK's ability to sell, transfer, convey, exchange or otherwise dispose of its assets. 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.
Because AEK's equity at risk is less than 1% of its total assets, it is considered to be a variable interest entity. Atmos Energy has the power to direct the most significant financial and operating activities of AEK, including billing, collections and remittance of customer cash receipts to enable AEK to service the principal and interest payments due under the Securitized Utility Tariff Bonds. Atmos Energy also has the obligation to absorb losses and rights to receive returns from AEK. Therefore, Atmos Energy is the primary beneficiary of AEK, and as a result, AEK is included in the consolidated financial statements of Atmos Energy. No gain or loss was recognized upon initial consolidation.
The Securitized Utility Tariff Property that was acquired by AEK is classified as a securitized intangible asset on our consolidated balance sheets. This securitized intangible asset will be amortized over 10 years, the estimated period needed to collect the required amounts from Atmos Energy's customers to service the Securitized Utility Tariff Bonds, with a remaining weighted average amortization period of 4.07 years as of September 30, 2025. The amortization expense related to the securitized intangible asset is included in depreciation and amortization expense in our consolidated statements of comprehensive income.
The following table summarizes the impact of AEK on our consolidated balance sheets, for the periods indicated:
September 30, 2025September 30, 2024
 (In thousands)
Restricted cash and cash equivalents$1,116 $1,516 
Other current assets$$
Securitized intangible asset, net$75,127 $82,844 
Accrued interest$331 $365 
Current maturities of securitized long-term debt$8,767 $8,207 
Securitized long-term debt$68,236 $76,871 
The following table summarizes the impact of AEK on our consolidated statements of comprehensive income, for the periods indicated:
Year Ended September 30
202520242023
 (In thousands)
Operating revenues$12,408 $13,660 $2,743 
Operation and maintenance expense(559)(427)— 
Amortization expense(7,717)(8,715)(1,398)
Interest expense, net(4,132)(4,518)(1,345)
Income before income taxes$— $— $— 
The following table summarizes the maturities of the securitized long-term debt and the amortization expense related to the securitized intangible asset expected to be recognized in our consolidated statements of comprehensive income:
Maturities of Securitized Long-Term DebtAmortization Expense of Securitized Intangible Asset
For the fiscal year ending:(In thousands)
2026$8,767 $8,555 
20279,086 9,001 
20289,561 9,471 
202910,060 9,966 
203010,585 10,486 
Thereafter28,944 27,648 
Total$77,003 $75,127 
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 September 30, 2025 is $77.0 million and $78.8 million, and as of September 30, 2024 is $85.1 million and $87.8 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 collected $2.02 billion of this amount and relieved the regulatory asset that we recorded in fiscal 2021 for costs incurred during Winter Storm Uri.
We began collecting the customer rate relief charges on October 1, 2023, and any such property collected is solely owned by the Finance Corporation and not available to pay creditors of Atmos Energy.
v3.25.3
Retirement and Postretirement Employee Benefit Plans
12 Months Ended
Sep. 30, 2025
Retirement Benefits [Abstract]  
Retirement and Postretirement Employee Benefit Plans Retirement and Postretirement Employee Benefit Plans
We have both funded and unfunded noncontributory defined benefit plans that together cover most of our employees. We also maintain a postretirement plan that provides health care benefits to retired employees. Finally, we sponsor a defined contribution plan that covers substantially all employees. These plans are discussed in further detail below.
As a rate regulated entity, most of our net periodic pension and other postretirement benefits costs are recoverable through our rates over a period of up to 15 years. A portion of these costs are capitalized into our rate base or deferred as a regulatory asset or liability. The remaining costs are recorded as a component of operation and maintenance expense or other non-operating expense. Additionally, the amounts that have not yet been recognized in net periodic pension cost that have been recorded as regulatory assets or liabilities are as follows:
Employee Pension PlanSupplemental
Executive
Retirement Plans
Postretirement
Plan
Total
 (In thousands)
September 30, 2025
Unrecognized prior service credit$— $— $(9,984)$(9,984)
Unrecognized actuarial (gain) loss(179,351)17,661 (116,690)(278,380)
$(179,351)$17,661 $(126,674)$(288,364)
September 30, 2024
Unrecognized prior service credit$— $— $(24,897)$(24,897)
Unrecognized actuarial (gain) loss(126,989)16,136 (111,500)(222,353)
$(126,989)$16,136 $(136,397)$(247,250)
Defined Benefit Plans
Employee Pension Plan
As of September 30, 2025, we maintained one cash balance defined benefit plan, the Atmos Energy Corporation Pension Account Plan (the Pension Plan). The Pension Plan was established effective January 1999 and covers most of the employees of Atmos Energy that were hired on or before September 30, 2010. Effective October 1, 2010, the Pension Plan was closed to new participants. The assets of the Pension Plan are held within the Atmos Energy Corporation Master Retirement Trust (the Master Trust).
Opening account balances were established for participants as of January 1999 equal to the present value of their respective accrued benefits under the pension plans which were previously in effect as of December 31, 1998. The Pension Plan credits an allocation to each participant’s account at the end of each year according to a formula based on the participant’s age, service, and total pay (excluding incentive pay). In addition, at the end of each year, a participant’s account is credited with interest on the employee’s prior year account balance. Participants are fully vested in their account balances after three years of service and may choose to receive their account balances as a lump sum or an annuity.
Generally, our funding policy is to contribute annually an amount in accordance with the requirements of the Employee Retirement Income Security Act of 1974 (ERISA), including the funding requirements under the Pension Protection Act of 2006 (PPA). However, additional voluntary contributions are made from time to time as considered necessary. Contributions are intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future.
During fiscal 2025 we made no contributions to the Pension Plan and during fiscal 2024 we contributed $5.0 million in cash to the Pension Plan to achieve a desired level of funding while maximizing the tax deductibility of this payment. Based upon market conditions at September 30, 2025, the current funded position of the Pension Plan, and the funding requirements under the PPA, we do not anticipate a minimum required contribution for fiscal 2026. However, we may consider whether a voluntary contribution is prudent to maintain certain funding levels.
We make investment decisions and evaluate performance of the assets in the Master Trust on a medium-term horizon of at least three to five years. We also consider our current financial status when making recommendations and decisions regarding the Master Trust’s assets. Finally, we strive to ensure the Master Trust’s assets are appropriately invested to maintain an acceptable level of risk and meet the Master Trust’s long-term asset investment policy adopted by the Qualified Retirement Plans and Trusts Committee, comprised of a group of executives appointed by the Board of Directors to oversee the Company's employee pension plan, defined contribution plan and postretirement benefit plan.
To achieve these objectives, we invest the Master Trust’s assets in equity securities, fixed income securities, interests in commingled pension trust funds, other investment assets, and cash and cash equivalents. Investments in equity securities are diversified among the market’s various subsectors in an effort to diversify risk and maximize returns. Fixed income securities are invested in investment grade securities. Cash equivalents are invested in securities that either are short term (less than 180 days) or readily convertible to cash with modest risk.
The following table presents asset allocation information for the Master Trust as of September 30, 2025 and 2024.
 Targeted
Allocation  Range
Actual
Allocation
September 30
Security Class20252024
Domestic equities
35%-55%
43.6%42.8%
International equities
10%-20%
15.5%15.8%
Fixed income
5%-45%
24.3%22.3%
Company stock
0%-15%
14.0%16.7%
Other assets
0%-20%
2.6%2.4%
At September 30, 2025 and 2024, the Pension Plan held 506,700 and 716,700 shares of our common stock which represented 14.0 percent and 16.7 percent of total Pension Plan assets. These shares generated dividend income for the Pension Plan of approximately $1.9 million and $2.3 million during fiscal 2025 and 2024.
Our Pension Plan expenses and liabilities are determined on an actuarial basis and are affected by numerous assumptions and estimates including the market value of plan assets, estimates of the expected return on plan assets, and assumed discount rates and demographic data. We review the estimates and assumptions underlying our Pension Plan annually based upon a September 30 measurement date. The development of our assumptions is fully described in our significant accounting policies in Note 2 to the consolidated financial statements. The actuarial assumptions used to determine the pension asset for the Pension Plan was determined as of September 30, 2025 and 2024 and the actuarial assumptions used to determine the net periodic pension cost for the Pension Plan was determined as of September 30, 2024, 2023, and 2022.
Additional assumptions are presented in the following table:
 Pension
Asset
Pension Cost
 20252024202520242023
Discount rate5.45 %5.02 %5.02 %6.10 %5.66 %
Rate of compensation increase3.50 %3.50 %3.50 %3.50 %3.50 %
Expected return on plan assets6.50 %6.50 %6.50 %6.25 %6.25 %
Interest crediting rate (1)
4.69 %4.69 %4.69 %4.69 %4.69 %
(1)    The interest crediting rate assumption for the development of the fiscal 2025 pension asset is 4.73% for calendar year 2026, then reverting back to 4.69% for all future years.
The following table presents the Pension Plan’s accumulated benefit obligation, projected benefit obligation, and funded status as of September 30, 2025 and 2024:
20252024
 (In thousands)
Accumulated benefit obligation$428,845 $448,353 
Change in projected benefit obligation:
Benefit obligation at beginning of year$470,902 $431,560 
Service cost10,047 9,546 
Interest cost23,164 25,731 
Actuarial (gain) loss(18,133)44,205 
Benefits paid(35,556)(40,140)
Benefit obligation at end of year450,424 470,902 
Change in plan assets:
Fair value of plan assets at beginning of year595,212 502,412 
Actual return on plan assets64,847 127,940 
Employer contributions— 5,000 
Benefits paid(35,556)(40,140)
Fair value of plan assets at end of year624,503 595,212 
Reconciliation:
Funded status174,079 124,310 
Unrecognized prior service cost— — 
Unrecognized net loss— — 
Net amount recognized$174,079 $124,310 

Net periodic pension cost for the Pension Plan for fiscal 2025, 2024, and 2023 is presented in the following table.
 Fiscal Year Ended September 30
 202520242023
 (In thousands)
Components of net periodic pension cost:
Service cost$10,047 $9,546 $10,805 
Interest cost (1)
23,164 25,731 24,924 
Expected return on assets (1)
(30,618)(28,808)(29,113)
Amortization of prior service credit (1)
— — (121)
Recognized actuarial gain (1)
— (67)— 
Net periodic pension cost$2,593 $6,402 $6,495 

(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 consolidated statements of comprehensive income or are capitalized on the consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements.
The following tables set forth by level, within the fair value hierarchy, the Pension Plan's assets at fair value as of September 30, 2025 and 2024. As required by authoritative accounting literature, assets are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The methods used to determine fair value for the assets held by the Pension Plan are fully described in Note 2 to the consolidated financial statements. Investments in our common/collective trusts and limited partnerships that are measured at net asset value per share equivalent are not classified in the fair value hierarchy. The net asset value amounts presented are intended to reconcile the fair value hierarchy to the total investments. In addition to the assets shown below, the Pension Plan had net accounts receivable of $5.1 million and $0.7 million at September 30, 2025 and 2024, which materially approximates fair value due to the short-term nature of these assets.
 Assets at Fair Value as of September 30, 2025
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Common stocks$284,573 $— $— $284,573 
Money market funds— 16,293 — 16,293 
Registered investment companies123,022 — — 123,022 
Government securities:
Mortgage-backed securities— 26,101 — 26,101 
U.S. treasuries15,021 26 — 15,047 
Corporate bonds— 32,517 — 32,517 
Asset-backed securities— 1,475 — 1,475 
Total investments measured at fair value$422,616 $76,412 $— 499,028 
Investments measured at net asset value:
Common/collective trusts (1)
95,558 
Limited partnerships (1)
24,843 
Total investments$619,429 

 Assets at Fair Value as of September 30, 2024
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Common stocks$289,301 $— $— $289,301 
Money market funds— 14,542 — 14,542 
Registered investment companies90,086 — — 90,086 
Government securities:
Mortgage-backed securities— 24,383 — 24,383 
U.S. treasuries9,398 27 — 9,425 
Corporate bonds— 31,986 — 31,986 
Total investments measured at fair value$388,785 $70,938 $— 459,723 
Investments measured at net asset value:
Common/collective trusts (1)
111,103 
Limited partnerships (1)
23,665 
Total investments$594,491 
(1)    The fair value of our common/collective trusts and limited partnerships are measured using the net asset value per share practical expedient. There are no redemption restrictions, redemption notice periods, or unfunded commitments for these investments. The redemption frequency is daily.
Supplemental Executive Retirement Plans
We have three nonqualified supplemental plans (the Supplemental Plans) which provide additional pension, disability, and death benefits to our officers and certain other employees of the Company.
The Supplemental Executive Benefits Plan (SEBP) covers our corporate officers and certain other employees of the Company who were employed on or before August 12, 1998. The SEBP is a defined benefit arrangement which provides a benefit equal to 75 percent of covered compensation under which benefits paid from the underlying qualified defined benefit plan are an offset to the benefits under the SEBP.
In August 1998, we adopted the Supplemental Executive Retirement Plan (SERP) (formerly known as the Performance-Based Supplemental Executive Benefits Plan), which covers all corporate officers selected to participate in the plan between August 12, 1998 and August 5, 2009. The SERP is a defined benefit arrangement which provides a benefit equal to 60 percent of covered compensation under which benefits paid from the underlying qualified defined benefit plan are an offset to the benefits under the SERP.
Effective August 5, 2009, we adopted a new defined benefit Supplemental Executive Retirement Plan (the 2009 SERP), for corporate officers or any other employees selected at the discretion of the Board. Under the 2009 SERP, a nominal account has been established for each participant, to which the Company contributes at the end of each calendar year an amount equal to ten percent (25 percent for members of the Management Committee appointed on or after January 1, 2016) of the total of each participant’s base salary and cash incentive compensation earned during each prior calendar year, beginning December 31, 2009. The benefits vest after three years of service and attainment of age 55 and earn interest credits at the same annual rate as the Company’s Pension Plan.
During fiscal 2024, we recognized settlement charges of $1.5 million and paid $9.6 million in lump sums in relation to the retirement of certain executives. During fiscal 2023, we recognized a settlement charge of $1.0 million and paid a $5.6 million lump sum in relation to the retirements of certain executives.
We review the estimates and assumptions underlying our Supplemental Plans annually based upon a September 30 measurement date using the same techniques as our Pension Plan. The actuarial assumptions used to determine the pension liability for the Supplemental Plans were determined as of September 30, 2025 and 2024 and the actuarial assumptions used to determine the net periodic pension cost for the Supplemental Plans were determined as of September 30, 2024, 2023, and 2022. These assumptions are presented in the following table:
 Pension
Liability
Pension Cost
 20252024202520242023
Discount rate (1)
5.14 %4.92 %4.92 %5.85 %5.50 %
Rate of compensation increase3.50 %3.50 %3.50 %3.50 %3.50 %
Interest crediting rate (2)
4.69 %4.69 %4.69 %4.69 %4.69 %
 (1)    Reflects a weighted average discount rate for pension cost for fiscal 2024 and 2023 due to the settlements during the year.
 (2)    The interest crediting rate assumption for the development of the fiscal 2025 pension liability is 4.73% for calendar year 2026, then reverting back to 4.69% for all future years.
The following table presents the Supplemental Plans’ accumulated benefit obligation, projected benefit obligation, and funded status as of September 30, 2025 and 2024:
20252024
 (In thousands)
Accumulated benefit obligation$73,570 $71,003 
Change in projected benefit obligation:
Benefit obligation at beginning of year$71,944 $75,898 
Service cost1,302 55 
Interest cost3,488 4,024 
Actuarial loss2,547 5,853 
Benefits paid(4,761)(4,285)
Settlements— (9,601)
Benefit obligation at end of year74,520 71,944 
Change in plan assets:
Fair value of plan assets at beginning of year— — 
Employer contribution— — 
Benefits paid— — 
Settlements— — 
Fair value of plan assets at end of year— — 
Reconciliation:
Funded status(74,520)(71,944)
Unrecognized prior service cost— — 
Unrecognized net loss— — 
Accrued pension cost$(74,520)$(71,944)
Assets for the Supplemental Plans are held in separate rabbi trusts. At September 30, 2025 and 2024, assets held in the rabbi trusts consisted of equity securities of $30.1 million and $31.1 million, which are included in our fair value disclosures in Note 17 to the consolidated financial statements.
Net periodic pension cost for the Supplemental Plans for fiscal 2025, 2024, and 2023 is presented in the following table.
 Fiscal Year Ended September 30
 202520242023
 (In thousands)
Components of net periodic pension cost:
Service cost$1,302 $55 $845 
Interest cost (1)
3,488 4,024 4,227 
Recognized actuarial loss (1)
1,022 501 691 
Settlements (1)
— 1,529 1,030 
Net periodic pension cost$5,812 $6,109 $6,793 

(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 consolidated statements of comprehensive income or are capitalized on the consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements.
Estimated Future Benefit Payments
The following benefit payments for our defined benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years:
Pension
Plan
Supplemental
Plans
 (In thousands)
2026$40,122 $6,277 
202739,190 9,627 
202838,729 28,392 
202938,798 3,783 
203038,777 3,615 
2031-2035178,831 31,031 
Postretirement Benefits Plan
We sponsor the Retiree Medical Plan for Retirees and Disabled Employees of Atmos Energy Corporation (the Retiree Medical Plan). This plan provides medical and prescription drug protection to all qualified participants based on their date of retirement. The Retiree Medical Plan provides different levels of benefits depending on the level of coverage chosen by the participants and the terms of predecessor plans. Effective January 1, 2022, the Retiree Medical Plan was amended to change the post-65 retiree coverage to Via Benefits with an Atmos Energy funded Health Reimbursement Account. Eligible post-65 retirees and post-65 spouses will be able to elect coverage through Via Benefits, including those that previously deferred or declined retiree coverage.
Generally, our funding policy is to contribute annually an amount in accordance with the requirements of ERISA. However, additional voluntary contributions are made annually as considered necessary. Contributions are intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. We expect to contribute between $13 million and $18 million to our Retiree Medical Plan during fiscal 2026.
We maintain a formal investment policy with respect to the assets in our Retiree Medical Plan to ensure the assets funding the Retiree Medical Plan are appropriately invested to maintain an acceptable level of risk. We also consider our current financial status when making recommendations and decisions regarding the Retiree Medical Plan.
We currently invest the assets funding our Retiree Medical Plan in diversified investment funds which consist of common stocks, preferred stocks, and fixed income securities. The diversified investment funds may invest up to 75 percent of assets in common stocks and convertible securities. The following table presents asset allocation information for the Retiree Medical Plan assets as of September 30, 2025 and 2024.
 Actual
Allocation
September 30
Security Class20252024
Diversified investment funds98.6%97.8%
Cash and cash equivalents1.4%2.2%
We review the estimates and assumptions underlying our Retiree Medical Plan annually based upon a September 30 measurement date using the same techniques as our Pension Plan and Supplemental Plans. The actuarial assumptions used to determine the postretirement asset for our Retiree Medical Plan were determined as of September 30, 2025 and 2024 and the actuarial assumptions used to determine the net periodic postretirement cost for the Retiree Medical Plan were determined as of September 30, 2024, 2023, and 2022.
The assumptions are presented in the following table:
 Postretirement
Asset
Postretirement Cost
 20252024202520242023
Discount rate5.47 %5.01 %5.01 %6.06 %5.61 %
Expected return on plan assets5.14 %5.14 %5.14 %4.94 %4.94 %
Initial trend rate7.00 %6.75 %6.75 %6.50 %6.25 %
Ultimate trend rate5.00 %5.00 %5.00 %5.00 %4.75 %
Ultimate trend reached in20342032203220302029

The following table presents the Retiree Medical Plan’s benefit obligation and funded status as of September 30, 2025 and 2024:
20252024
 (In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year$269,391 $234,004 
Service cost8,132 6,028 
Interest cost13,463 14,034 
Plan participants’ contributions1,993 2,102 
Actuarial (gain) loss(8,733)31,135 
Benefits paid(19,065)(17,912)
Plan amendments1,873 — 
Benefit obligation at end of year267,054 269,391 
Change in plan assets:
Fair value of plan assets at beginning of year300,692 255,800 
Actual return on plan assets21,500 47,857 
Employer contributions— — 
Benefits paid(2,808)(2,965)
Fair value of plan assets at end of year319,384 300,692 
Reconciliation:
Funded status52,330 31,301 
Unrecognized transition obligation— — 
Unrecognized prior service cost— — 
Unrecognized net loss— — 
Accrued postretirement cost$52,330 $31,301 
Net periodic postretirement cost for the Retiree Medical Plan for fiscal 2025, 2024, and 2023 is presented in the following table.
 Fiscal Year Ended September 30
 202520242023
 (In thousands)
Components of net periodic postretirement cost:
Service cost$8,132 $6,028 $6,183 
Interest cost (1)
13,463 14,034 13,911 
Expected return on assets (1)
(15,325)(12,511)(11,215)
Amortization of prior service credit (1)
(13,040)(13,040)(13,142)
Recognized actuarial gain (1)
(9,716)(10,872)(7,452)
Net periodic postretirement cost$(16,486)$(16,361)$(11,715)

(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 consolidated statements of comprehensive income or are capitalized on the consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements.
We are currently recovering other postretirement benefits costs through our regulated rates in substantially all of our service areas under accrual accounting as prescribed by accounting principles generally accepted in the United States. Other postretirement benefits costs have been specifically addressed in rate orders in each jurisdiction served by our Kentucky/Mid-States, West Texas, Mid-Tex, and Mississippi Divisions as well as our Kansas jurisdiction and APT or have been included in a rate case and not disallowed. Management believes that this accounting method is appropriate and will continue to seek rate recovery of accrual-based expenses in its ratemaking jurisdictions that have not yet approved the recovery of these expenses.
The following tables set forth by level, within the fair value hierarchy, the Retiree Medical Plan’s assets at fair value as of September 30, 2025 and 2024. The methods used to determine fair value for the assets held by the Retiree Medical Plan are fully described in Note 2 to the consolidated financial statements.
 Assets at Fair Value as of September 30, 2025
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Money market funds$— $4,428 $— $4,428 
Registered investment companies314,956 — — 314,956 
Total investments measured at fair value$314,956 $4,428 $— $319,384 
 
 Assets at Fair Value as of September 30, 2024
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Money market funds$— $6,633 $— $6,633 
Registered investment companies294,059 — — 294,059 
Total investments measured at fair value$294,059 $6,633 $— $300,692 
Estimated Future Benefit Payments
The following benefit payments paid by the Company, retirees, and prescription drug subsidies for our Retiree Medical Plan, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years.
Company
Payments
Retiree
Payments
Subsidy
Payments
Total
Postretirement
Benefits
 (In thousands)
2026$18,898 $2,425 $— $21,323 
202718,859 2,320 — 21,179 
202818,783 2,186 — 20,969 
202919,011 2,112 — 21,123 
203019,364 2,083 — 21,447 
2031-2035104,216 10,770 — 114,986 
Defined Contribution Plan
The Atmos Energy Corporation Retirement Savings Plan and Trust (the Retirement Savings Plan) covers substantially all employees and is subject to the provisions of Section 401(k) of the Internal Revenue Code. Newly hired employees automatically become participants of the Retirement Savings Plan on the date of employment at a contribution rate of five percent. They are eligible to receive matching contributions immediately upon enrollment, which vest after completing one year of service. Participants may elect a salary reduction up to a maximum of 65 percent of eligible compensation, as defined by the Retirement Savings Plan, not to exceed the maximum allowed by the Internal Revenue Service. Participants who contribute less than 10 percent will have their contribution percent increased by one percent annually until a 10 percent salary deferral rate is achieved, unless the participant opts out of this election. We match 100 percent of a participant’s contributions, limited to five percent of the participant’s salary. Effective January 1, 2026, the matching contribution will be increased to a limit of six percent of the participant's salary. Additionally, employees hired on or after October 1, 2010 receive a fixed annual contribution of four percent of eligible earnings. The Retirement Savings Plan also contains an elective Roth deferral feature. Finally, participants are permitted to take out a loan against their accounts subject to certain restrictions.
Matching and fixed annual contributions to the Retirement Savings Plan are expensed as incurred and amounted to $34.3 million, $26.8 million and $23.9 million for fiscal years 2025, 2024, and 2023. At September 30, 2025 and 2024, the Retirement Savings Plan held 1.1 percent and 1.2 percent of our outstanding common stock.
v3.25.3
Stock and Other Compensation Plans
12 Months Ended
Sep. 30, 2025
Share-Based Payment Arrangement [Abstract]  
Stock and Other Compensation Plans Stock and Other Compensation Plans
Stock-Based Compensation Plans
Total stock-based compensation cost was $33.2 million, $25.4 million, and $23.7 million for the fiscal years ended September 30, 2025, 2024, and 2023. Of this amount, $20.5 million, $14.7 million, and $13.5 million was capitalized.
1998 Long-Term Incentive Plan
We have the 1998 Long-Term Incentive Plan (LTIP), which provides a comprehensive, long-term incentive compensation plan providing for discretionary awards of incentive stock options, non-qualified stock options, stock appreciation rights, bonus stock, time-lapse restricted stock, time-lapse restricted stock units, performance-based restricted stock units, and stock units to certain employees and non-employee directors of the Company and our subsidiaries. The objectives of this plan include attracting and retaining the best available personnel and providing for additional performance incentives by providing employees with the opportunity to acquire common stock.
We are authorized to grant awards up to a maximum cumulative amount of 13.2 million shares of common stock under this plan subject to certain adjustment provisions. As of September 30, 2025, non-qualified stock options, bonus stock, time-lapse restricted stock, time-lapse restricted stock units, performance-based restricted stock units, and stock units had been issued under this plan, and 2.2 million shares are available for future issuance.
Restricted Stock Units Award Grants
As noted above, the LTIP provides for discretionary awards of restricted stock units to help attract, retain, and reward certain employees of Atmos Energy and its subsidiaries. Certain of these awards vest based upon the passage of time and other awards vest based upon the passage of time and the achievement of specified performance targets. The fair value of the awards
granted is based on the market price of our stock at the date of grant. We estimate forfeitures using our historical forfeiture rate. The associated expense is recognized ratably over the vesting period. We use authorized and unissued shares to meet share requirements for the vesting of restricted stock units.
Employees who are granted time-lapse restricted stock units under our LTIP have a nonforfeitable right to dividend equivalents that are paid at the same rate and at the same time at which they are paid on shares of stock without restrictions. Time-lapse restricted stock units contain only a service condition that the employee recipients render continuous services to the Company for a period of three years from the date of grant, except for accelerated vesting in the event of death, disability, change of control of the Company or termination without cause (with certain exceptions). There are no performance conditions required to be met for employees to be vested in time-lapse restricted stock units.
Employees who are granted performance-based restricted stock units under our LTIP have a forfeitable right to dividend equivalents that accrue at the same rate at which they are paid on shares of stock without restrictions. Dividend equivalents on the performance-based restricted stock units are paid either in cash or in the form of shares upon the vesting of the award. Performance-based restricted stock units contain a service condition that the employee recipients render continuous services to the Company for a period of three years from the beginning of the applicable three-year performance period, except for accelerated vesting in the event of death, disability, change of control of the Company or termination without cause (with certain exceptions) and a performance condition based on a cumulative earnings per share target amount.
The following summarizes information regarding the restricted stock units granted under the plan during the fiscal years ended September 30, 2025, 2024, and 2023:
 202520242023
 Number of
Restricted
Units
Weighted
Average
Grant-Date
Fair
Value
Number of
Restricted
Units
Weighted
Average
Grant-Date
Fair
Value
Number of
Restricted
Units
Weighted
Average
Grant-Date
Fair
Value
Nonvested at beginning of year397,929 $113.78 389,957 $109.10 381,295 $105.69 
Granted229,828 135.68 212,207 117.11 241,436 109.78 
Vested(215,806)111.75 (201,834)108.56 (220,929)104.05 
Forfeited(3,815)127.58 (2,401)115.44 (11,845)107.47 
Nonvested at end of year408,136 $127.74 397,929 $113.78 389,957 $109.10 
As of September 30, 2025, there was $21.6 million of total unrecognized compensation cost related to nonvested restricted stock units granted under the LTIP. That cost is expected to be recognized over a weighted average period of 1.3 years. The fair value of restricted stock vested during the fiscal years ended September 30, 2025, 2024, and 2023 was $24.0 million, $21.6 million, and $22.8 million.
Other Plans
Direct Stock Purchase Plan
We maintain a Direct Stock Purchase Plan, open to all investors, which allows participants to have all or part of their cash dividends paid quarterly in additional shares of our common stock. The minimum initial investment required to join the plan is $1,250. Direct Stock Purchase Plan participants may purchase additional shares of our common stock as often as weekly with voluntary cash payments of at least $25, up to an annual maximum of $100,000.
Equity Incentive and Deferred Compensation Plan for Non-Employee Directors
We have an Equity Incentive and Deferred Compensation Plan for Non–Employee Directors, which provides non-employee directors of Atmos Energy with the opportunity to defer receipt, until retirement, of compensation for services rendered to the Company and invest deferred compensation into either a cash account or a stock account.
Other Discretionary Compensation Plans
We have an annual incentive program covering substantially all employees to give each employee an opportunity to share in our financial success based on the achievement of key performance measures considered critical to achieving business objectives for a given year with minimum and maximum thresholds. The Company must meet the minimum threshold for the plan to be funded and distributed to employees. These performance measures may include earnings growth objectives, improved cash flow objectives, or crucial customer satisfaction and safety results. We monitor progress towards the achievement of the performance measures throughout the year and record accruals based upon the expected payout using the
best estimates available at the time the accrual is recorded. During the last several fiscal years, we have used earnings per share as our sole performance measure.
v3.25.3
Details of Selected Financial Statement Captions
12 Months Ended
Sep. 30, 2025
Balance Sheet Related Disclosures [Abstract]  
Details of Selected Financial Statement Captions Details of Selected Financial Statement Captions
The following tables provide additional information regarding the composition of certain financial statement captions.

Balance Sheet
Accounts receivable
Accounts receivable was comprised of the following at September 30, 2025 and 2024:
 September 30
 20252024
 (In thousands)
Billed accounts receivable$213,651 $220,869 
Unbilled revenue140,651 123,550 
Insurance receivable22,940 51,715 
Other accounts receivable43,526 6,804 
Total accounts receivable420,768 402,938 
Less: allowance for uncollectible accounts(45,259)(37,056)
Net accounts receivable$375,509 $365,882 
Other current assets
Other current assets as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
 (In thousands)
Deferred gas costs$140,626 $159,762 
Winter Storm Uri incremental costs5,841 3,949 
Prepaid expenses80,495 74,780 
Taxes receivable8,948 14,332 
Materials and supplies20,076 16,961 
Assets from risk management activities5,303 2,091 
Regulatory assets (See Note 3)
33,311 12,297 
Other7,027 3,896 
Total$301,627 $288,068 
Property, plant and equipment
Property, plant and equipment was comprised of the following as of September 30, 2025 and 2024:
 September 30
 20252024
 (In thousands)
Storage plant$790,621 $708,617 
Transmission plant6,308,557 5,713,831 
Distribution plant19,788,099 17,304,207 
General plant1,102,931 1,019,018 
Intangible plant38,612 38,612 
28,028,820 24,784,285 
Construction in progress1,235,316 1,063,798 
29,264,136 25,848,083 
Less: accumulated depreciation and amortization(3,971,146)(3,643,716)
Net property, plant and equipment (1)
$25,292,990 $22,204,367 
    
(1)     Net property, plant and equipment includes plant acquisition adjustments of $(21.1) million and $(22.9) million at September 30, 2025 and 2024.

Deferred charges and other assets
Deferred charges and other assets as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
 (In thousands)
Marketable securities$114,938 $110,594 
Regulatory assets (See Note 3)
428,951 396,958 
Operating lease right of use assets (See Note 7)
293,934 249,556 
Winter Storm Uri incremental costs— 6,424 
Assets from risk management activities4,594 94,197 
Pension and postretirement assets226,409 155,611 
Other28,627 30,343 
Total$1,097,453 $1,043,683 
Accounts payable and accrued liabilities
Accounts payable and accrued liabilities as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
(In thousands)
Trade accounts payable$380,999 $341,948 
Accrued gas payable37,073 19,125 
Accrued liabilities88,444 84,324 
Total$506,516 $445,397 
Other current liabilities
Other current liabilities as of September 30, 2025 and 2024 were comprised of the following accounts.
 
 September 30
 20252024
 (In thousands)
Customer credit balances and deposits$56,185 $62,085 
Accrued employee costs69,062 64,141 
Deferred gas costs6,879 9,142 
Operating lease liabilities (See Note 7)
45,010 34,340 
Accrued interest122,459 106,116 
Liabilities from risk management activities6,339 7,324 
Taxes payable237,965 215,857 
Pension and postretirement liabilities6,122 4,622 
Regulatory cost of removal obligation108,558 99,217 
APT annual adjustment mechanism68,094 35,924 
Regulatory excess deferred taxes (See Note 15)
72,792 79,686 
Other36,092 32,166 
Total$835,557 $750,620 
Deferred credits and other liabilities
Deferred credits and other liabilities as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
 (In thousands)
Pension and postretirement liabilities$68,398 $67,322 
Operating lease liabilities (See Note 7)
262,549 224,498 
Customer advances for construction9,573 7,973 
Other regulatory liabilities (See Note 3)
332,017 279,979 
Asset retirement obligation7,428 7,942 
Liabilities from risk management activities146 313 
APT annual adjustment mechanism31,299 37,195 
Unrecognized tax benefits (See Note 15)
50,210 46,174 
Other22,702 20,536 
Total$784,322 $691,932 
Statement of Comprehensive Income
Other non-operating income
Other non-operating income for the fiscal years ended September 30, 2025, 2024, and 2023 were comprised of the following accounts.
Year Ended September 30
202520242023
(In thousands)
Equity component of AFUDC$75,425 $58,234 $64,019 
Performance-based rate program8,485 8,389 7,093 
Pension and other postretirement non-service credit14,372 10,820 8,955 
Interest income29,944 22,887 7,207 
Community support spending(21,114)(20,016)(12,027)
Unrealized gains on equity securities174 3,562 1,406 
Miscellaneous(17,545)(12,830)(6,878)
Total$89,741 $71,046 $69,775 
Statement of Cash Flows
Supplemental disclosures of cash flow information for the fiscal years ended September 30, 2025, 2024, and 2023 were as follows:
 Year Ended September 30
 202520242023
 (In thousands)
Cash Paid (Received) During The Period For:
Interest (1)
$349,222 $308,872 $249,066 
Income taxes:
Federal$(5,000)$8,200 $(4,500)
State of Texas7,095 5,372 17,200 
State of Louisiana2,357 1,739 2,232 
Other states— 38 36 
$4,452 $15,349 $14,968 
Non-Cash Transactions:
Capital expenditures included in current liabilities$327,814 $299,908 $186,912 
(1)    Cash paid during the period for interest, net of amounts capitalized was $155.3 million, $163.5 million, and $117.9 million for the fiscal years ended September 30, 2025, 2024, and 2023.
v3.25.3
Commitments and Contingencies
12 Months Ended
Sep. 30, 2025
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. Atmos Energy is working closely with the NTSB and other state and federal regulators to help determine causal factors.
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. Atmos Energy is working closely with the NTSB and other state and federal regulators to help determine causal factors.
We are a party to various other litigation and environmental-related matters or claims that have arisen in the ordinary course of our business. While the results of such litigation and response actions to such environmental-related matters or claims cannot be predicted with certainty, we continue to believe the final outcome of such litigation and matters or claims will not have a material adverse effect on our financial condition, results of operations, or cash flows.
Purchase Commitments
Our distribution divisions maintain supply contracts with several vendors that generally cover a period of up to one year. Commitments for estimated base gas volumes are established under these contracts on a monthly basis at contractually negotiated prices. Commitments for incremental daily purchases are made as necessary during the month in accordance with the terms of the individual contract.
Our Mid-Tex Division also maintains 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 trading hubs or fixed price contracts. At September 30, 2025, we were committed to purchase 73.4 Bcf within one year and 114.9 Bcf within two to three years under indexed contracts. At September 30, 2025, we were committed to purchase 21.0 Bcf within one year under fixed price contracts with a weighted average price of $2.70 per Mcf. Purchases under these contracts totaled $153.4 million, $105.7 million, and $182.0 million for 2025, 2024, and 2023.
Rate Regulatory Proceedings
As of September 30, 2025, routine rate regulatory proceedings were in progress in some of our service areas, which are discussed in further detail above in the Business — Ratemaking Activity section.
v3.25.3
Income Taxes
12 Months Ended
Sep. 30, 2025
Income Tax Disclosure [Abstract]  
Income Taxes Income Taxes
Income Tax Expense
Reconciliations of the provision for income taxes computed at the statutory rate of 21 percent to the reported provisions for income taxes from continuing operations for 2025, 2024, and 2023 are set forth below:
202520242023
 (In thousands)%(In thousands)%(In thousands)%
U.S federal statutory tax rate$310,387 21.0 %$259,513 21.0 %$209,925 21.0 %
State and local income taxes, net of federal income tax effect (1)
24,254 1.6 %27,367 2.2 %19,853 2.0 %
Changes in valuation allowances— — %1,106 0.1 %— — %
Changes in unrecognized tax benefits2,004 0.1 %926 0.1 %5,302 0.5 %
Nontaxable or nondeductible items741 0.1 %2,464 0.2 %1,000 0.1 %
Amortization of excess deferred taxes(60,727)(4.1)%(100,270)(8.1)%(123,953)(12.4)%
Other, net2,621 0.2 %1,775 0.1 %1,652 0.2 %
Income tax expense$279,280 18.9 %$192,881 15.6 %$113,779 11.4 %
(1)    The states that contribute to the majority (greater than 50%) of the tax effect in this category include Texas and Louisiana.
Deferred income taxes reflect the tax effect of differences between the basis of assets and liabilities for book and tax purposes. The tax effect of temporary differences that gave rise to significant components of the deferred tax liabilities and deferred tax assets at September 30, 2025 and 2024 are presented below:
20252024
 (In thousands)
Deferred tax assets:
Employee benefit plans$34,202 $41,184 
Net operating loss carryforwards473,642 484,816 
Charitable and other credit carryforwards14,200 12,301 
Regulatory excess deferred tax31,387 46,330 
Lease asset72,973 63,747 
Other31,145 34,934 
Total deferred tax assets657,549 683,312 
Valuation allowance(1,365)(1,457)
Net deferred tax assets656,184 681,855 
Deferred tax liabilities:
Difference in net book value and net tax value of assets(3,200,535)(2,914,854)
Gas cost adjustments(43,819)(49,443)
Winter Storm Uri regulatory asset(17,993)(20,846)
Lease liability(66,831)(57,177)
Rate deferral adjustment(64,640)(50,571)
Interest rate agreements(135,640)(134,536)
Other(45,073)(47,770)
Total deferred tax liabilities(3,574,531)(3,275,197)
Net deferred tax liabilities$(2,918,347)$(2,593,342)
At September 30, 2025, we had $435.3 million (tax effected) of federal net operating loss carryforwards. The federal net operating loss carryforwards are available to offset future taxable income and have no expiration date. The Company has $11.8 million (tax effected) charitable contribution carryforwards to offset future taxable income as of September 30, 2025.
The Company also has $38.3 million (tax effected) of state net operating loss carryforwards (net of $10.1 million of federal effects) and $2.4 million of state tax credits carryforwards (net of $0.6 million of federal effects). Depending on the jurisdiction in which the state net operating loss was generated, the carryforwards expiration period begins in fiscal 2026.
At September 30, 2025 and 2024, we had recorded liabilities associated with unrecognized tax benefits totaling $60.3 million and $57.8 million, which includes $10.1 million and $11.6 million in deferred tax liabilities. The following table reconciles the beginning and ending balance of our unrecognized tax benefits:
202520242023
(In thousands)
Unrecognized tax benefits - beginning balance$57,797 $58,638 $52,683 
Decrease resulting from prior period tax positions(1,759)(2,867)(631)
Decrease resulting from a lapse in statute of limitations(5,699)(6,188)— 
Increase resulting from current period tax positions9,993 8,214 6,586 
Unrecognized tax benefits - ending balance60,332 57,797 58,638 
Less: deferred federal and state income tax benefits(12,670)(12,137)(12,314)
Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year (1)
$47,662 $45,660 $46,324 
(1)    As of September 30, 2025, there is an anticipated $43.3 million regulatory offset and associated impact to tax expense to be recorded upon recognition of unrecognized tax benefits.
The Company recognizes interest accrued related to unrecognized tax benefits in interest expense and penalties included within interest charges in our consolidated statements of comprehensive income. During the years ended September 30, 2025, 2024, and 2023, the Company recognized approximately $0.1 million, $0.1 million, and $3.4 million in interest and penalties.
The Company had approximately $15.1 million for the payment of interest and penalties accrued at September 30, 2025, 2024, and 2023.
We file income tax returns in the U.S. federal jurisdiction as well as in various states where we have operations. We have concluded substantially all U.S. federal income tax matters through fiscal year 2009 and concluded substantially all Texas income tax matters through fiscal year 2010.
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. As of September 30, 2025 and 2024, $72.8 million and $79.7 million is recorded in other current liabilities.
Currently, the regulatory excess net deferred tax liability of $140.5 million is being returned over various periods. Of this amount, $91.8 million is being returned to customers over 36 - 60 months. An additional $47.7 million is being returned to customers on a provisional basis over 15 - 69 years until our regulators establish the final refund periods. The refund of the remaining $1.0 million will be addressed in future rate proceedings.
v3.25.3
Financial Instruments
12 Months Ended
Sep. 30, 2025
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. Our financial instruments do not contain any credit-risk-related or other contingent features that could cause accelerated payments when our financial instruments are in net liability positions.
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.
In jurisdictions where we are permitted to mitigate commodity price risk through financial instruments, the relevant regulatory authorities may establish the level of heating season gas purchases that can be hedged. Our distribution gas supply department is responsible for executing this segment’s commodity risk management activities in conformity with regulatory requirements. Historically, if the regulatory authority does not establish this level, we seek to hedge between 25 and 50 percent of anticipated heating season gas purchases using financial instruments. For the 2024-2025 heating season (generally October through March), in the jurisdictions where we are permitted to utilize financial instruments, we hedged approximately 24.0 Bcf of the winter flowing gas requirements at a weighted average cost of approximately $3.83 per Mcf. 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 consolidated balance sheet and statements of comprehensive income.
As of September 30, 2025, 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 September 30, 2025, we had 32,566 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 September 30, 2025 and 2024. As discussed in Note 2 to the consolidated financial statements, we report our financial instruments as risk management assets and liabilities, each of which is classified as current or noncurrent based upon the anticipated settlement date of the underlying financial instrument. The gross amounts of recognized assets and liabilities are netted within our consolidated balance sheets to the extent that we have netting arrangements with the counterparties. However, as of September 30, 2025 and 2024, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
Balance Sheet LocationAssetsLiabilities
   (In thousands)
September 30, 2025
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)
 
Balance Sheet LocationAssetsLiabilities
   (In thousands)
September 30, 2024
Designated As Hedges:
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities
$91,981 $— 
Total91,981 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities
2,091 (7,324)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities
2,216 (313)
Total4,307 (7,637)
Gross / Net Financial Instruments$96,288 $(7,637)
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 designate 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 consolidated statements of comprehensive income for the years ended September 30, 2025, 2024, and 2023 was $(20.5) million, $(12.8) million, and $(2.7) million.
The following table summarizes the gains and losses arising from hedging transactions that were recognized as a component of other comprehensive income, net of taxes, for the years ended September 30, 2025 and 2024.
 Fiscal Year Ended
September 30
 20252024
 (In thousands)
Increase (decrease) in fair value:
Interest rate agreements$24,208 $(43,430)
Recognition of gains in earnings due to settlements:
Interest rate agreements(14,904)(9,965)
Total other comprehensive income (loss) from hedging, net of tax$9,304 $(53,395)
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 September 30, 2025, we had $474.8 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.
Interest Rate
Agreements
 (In thousands)
2026$19,093 
202719,093 
202819,093 
202919,093 
203019,093 
Thereafter379,341 
Total$474,806 
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 statements 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.
v3.25.3
Fair Value Measurements
12 Months Ended
Sep. 30, 2025
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 and restricted cash and cash equivalents, accounts receivable, and accounts payable at carrying value, which substantially approximates fair value due to the short-term nature of these assets and liabilities. For other financial assets and liabilities, we primarily use quoted market prices and other observable market pricing information to minimize the use of unobservable pricing inputs in our measurements when determining fair value. The methods used to determine fair value for our assets and liabilities are fully described in Note 2 to the consolidated financial statements.
Fair value measurements also apply to the valuation of our pension and postretirement plan assets. The fair value of these assets is presented in Note 11 to the consolidated financial statements.
Quantitative Disclosures
Financial Instruments
The classification of our fair value measurements requires judgment regarding the degree to which market data are observable or corroborated by observable market data. 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 September 30, 2025 and 2024. As required under authoritative accounting literature, 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
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 $— $— $6,485 
Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)
Netting and
Cash
Collateral
September 30, 2024
 (In thousands)
Assets:
Financial instruments$— $96,288 $— $— $96,288 
Debt and equity securities
Registered investment companies28,311 — — — 28,311 
Bond mutual funds40,341 — — — 40,341 
Bonds (2)
— 39,142 — — 39,142 
Money market funds— 2,800 — — 2,800 
Total debt and equity securities68,652 41,942 — — 110,594 
Total assets$68,652 $138,230 $— $— $206,882 
Liabilities:
Financial instruments$— $7,637 $— $— $7,637 
 
(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 which are valued at cost.
(2)Our investments in bonds are considered available-for-sale debt securities in accordance with current accounting guidance.
Debt and equity securities are comprised of our available-for-sale debt securities and our equity securities. We 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 September 30, 2025, no allowance for credit losses was recorded for our available-for-sale debt securities. At September 30, 2025 and 2024, the amortized cost of our available-for-sale debt securities was $42.5 million and $38.9 million. At September 30, 2025 we maintained investments in bonds that have contractual maturity dates ranging from October 2025 through January 2028.
Other Fair Value Measures
In addition to the financial instruments above, we have several financial and nonfinancial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents and restricted cash and cash equivalents, accounts receivable, accounts payable, finance leases, and debt, which are recorded at carrying value. The nonfinancial assets and liabilities include asset retirement obligations and pension and postretirement plan assets. For cash and cash equivalents and restricted cash and cash equivalents, accounts receivable, accounts payable, and finance leases we consider carrying value to materially approximate fair value due to the short-term nature of these assets and liabilities.
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 following table presents the carrying value and fair value of our long-term debt, excluding finances leases, debt issuance costs and original issue premium or discount, as of September 30, 2025:
 September 30, 2025
 (In thousands)
Carrying Amount$8,935,000 
Fair Value$8,272,978 
v3.25.3
Concentration of Credit Risk
12 Months Ended
Sep. 30, 2025
Risks and Uncertainties [Abstract]  
Concentration of Credit Risk Concentration of Credit Risk
Credit risk is the risk of financial loss to us if a customer fails to perform its contractual obligations. We engage in transactions for the purchase and sale of products and services with major companies in the energy industry and with industrial, commercial, residential, and municipal energy consumers. These transactions principally occur in the southern and midwestern regions of the United States. We believe that this geographic concentration does not contribute significantly to our overall exposure to credit risk. Credit risk associated with trade accounts receivable for the distribution segment is mitigated by the large number of individual customers and the diversity in our customer base. The credit risk for our pipeline and storage segment is not significant.
v3.25.3
Insider Trading Arrangements
3 Months Ended
Sep. 30, 2025
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
v3.25.3
Insider Trading Policies and Procedures
12 Months Ended
Sep. 30, 2025
Insider Trading Policies and Procedures [Line Items]  
Insider Trading Policies and Procedures Adopted true
v3.25.3
Cybersecurity Risk Management and Strategy Disclosure
12 Months Ended
Sep. 30, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]  
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]
We continuously assess our risk of cyber threats to adapt quickly to the ever-changing challenges and risks surrounding cybersecurity. Atmos Energy has implemented policies, procedures, and controls to identify, protect, detect, and respond to
cyberattacks or acts of online terrorism. Atmos Energy is also subject to the U.S. Department of Homeland Security Transportation Security Administration (TSA) security directive for our natural gas pipeline monitoring and control systems.
The potential impact of cybersecurity risks on our business operations, results of operations, or financial condition is discussed in the “Technology and Cybersecurity Risks” section of Item 1A “Risk Factors.” We have not had any material cybersecurity breaches or incidents and have not incurred any material expenses, penalties, or settlement costs related to any cybersecurity breaches or incidents. However, measures that we take to identify, protect, detect, and respond from cybersecurity breaches or incidents may be insufficient or become ineffective, and there are no assurances that cybersecurity breaches or incidents will not impact our business operations and strategy, results of operations, and financial condition in the future.
The following describes our risk management and strategy and corporate governance as it pertains to cybersecurity.
Risk Management and Strategy
Atmos Energy’s cybersecurity program leverages the National Institute of Standards and Technology (NIST) Cybersecurity Framework (CSF) in its design of controls intended to reduce the risk and potential impact of cybersecurity incidents. This comprehensive approach encompasses continuous monitoring, risk assessments, a cybersecurity incident response plan, and regular evaluations to align our practices with industry standards. Additionally, we actively engage in cybersecurity risk management practices and continually improve procedures and practices to support the continued safe and reliable delivery of natural gas to our customers.
The identification and management of cybersecurity risk is a component of our Integrated Risk Management process, which applies adaptive process improvement to help us respond to the changing cybersecurity landscape. Additionally, we use third parties to enhance our collective capability to monitor, detect, and respond to cybersecurity incidents. Further, we maintain collaborative relationships with government officials, law enforcement, and industry peers to keep informed of trends and potential cyber tactics. Finally, we maintain cybersecurity insurance coverage that we believe is appropriate for the size and complexity of our business.
We have an information technology cybersecurity incident response plan to manage cybersecurity incidents. The plan provides guidelines for actions in response to cyber security incidents that may occur at or otherwise affect Atmos Energy. These guidelines include notification to a cross-functional management team to assess incident materiality and an escalation process to members of our senior management team and our Board of Directors. This plan, which is periodically reviewed and tested, is supported by third parties to provide guidance and support to our cybersecurity management team.
We also address cybersecurity risks associated with third-party service providers, including those in our supply chain or who have access to our data or our information technology systems. Atmos Energy currently conducts cyber assessments on potential vendors that will have access to information technology systems, data or facilities that house such systems or data. Following approval, those vendors are contractually required to manage their cybersecurity risks and provide notification in the event of a cybersecurity incident.
Cybersecurity Risk Management Processes Integrated [Flag] true
Cybersecurity Risk Management Processes Integrated [Text Block]
Atmos Energy’s cybersecurity program leverages the National Institute of Standards and Technology (NIST) Cybersecurity Framework (CSF) in its design of controls intended to reduce the risk and potential impact of cybersecurity incidents. This comprehensive approach encompasses continuous monitoring, risk assessments, a cybersecurity incident response plan, and regular evaluations to align our practices with industry standards. Additionally, we actively engage in cybersecurity risk management practices and continually improve procedures and practices to support the continued safe and reliable delivery of natural gas to our customers.
The identification and management of cybersecurity risk is a component of our Integrated Risk Management process, which applies adaptive process improvement to help us respond to the changing cybersecurity landscape. Additionally, we use third parties to enhance our collective capability to monitor, detect, and respond to cybersecurity incidents. Further, we maintain collaborative relationships with government officials, law enforcement, and industry peers to keep informed of trends and potential cyber tactics. Finally, we maintain cybersecurity insurance coverage that we believe is appropriate for the size and complexity of our business.
Cybersecurity Risk Management Third Party Engaged [Flag] true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag] true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag] false
Cybersecurity Risk Board of Directors Oversight [Text Block]
Our Vice President and Chief Information Officer (CIO), who has over two decades of experience in information technology, is responsible for overseeing our cybersecurity program. The CIO oversees an IT Information security team responsible for our overall cybersecurity program. This team is comprised of several IT professionals with varying degrees of cybersecurity experience and is led by our Director – Cybersecurity who has over 30 years of experience in information technology and cybersecurity. The Director – Cybersecurity reports to the CIO, who reports to the Senior Vice President and Chief Financial Officer.
The CIO is a member of the Company’s Risk Management and Compliance Committee (RMCC). The RMCC is comprised of members from the senior leadership team and is responsible for overseeing enterprise-wide risk management across all categories, including cybersecurity. The RMCC is overseen by the Company’s Management Committee, which is comprised of the President and Chief Executive Officer, Senior Vice President and Chief Financial Officer, Senior Vice President, Utility Operations, Senior Vice President, General Counsel & Corporate Secretary, Senior Vice President, Human Resources, and Senior Advisor. The CIO provides regular cybersecurity updates to the Audit Committee of the Board of Directors and the Management Committee. These updates address prevention, detection, mitigation, and remediation of cybersecurity incidents, as well as risks, threats, and the threat landscape.
The Audit Committee of the Board of Directors oversees the company's cybersecurity risks. Additionally, our Board of Directors periodically engages with third-party advisors to provide further education about cybersecurity risks.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block] Our Vice President and Chief Information Officer (CIO), who has over two decades of experience in information technology, is responsible for overseeing our cybersecurity program.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block] The CIO provides regular cybersecurity updates to the Audit Committee of the Board of Directors and the Management Committee.
Cybersecurity Risk Role of Management [Text Block]
Our Vice President and Chief Information Officer (CIO), who has over two decades of experience in information technology, is responsible for overseeing our cybersecurity program. The CIO oversees an IT Information security team responsible for our overall cybersecurity program. This team is comprised of several IT professionals with varying degrees of cybersecurity experience and is led by our Director – Cybersecurity who has over 30 years of experience in information technology and cybersecurity. The Director – Cybersecurity reports to the CIO, who reports to the Senior Vice President and Chief Financial Officer.
The CIO is a member of the Company’s Risk Management and Compliance Committee (RMCC). The RMCC is comprised of members from the senior leadership team and is responsible for overseeing enterprise-wide risk management across all categories, including cybersecurity. The RMCC is overseen by the Company’s Management Committee, which is comprised of the President and Chief Executive Officer, Senior Vice President and Chief Financial Officer, Senior Vice President, Utility Operations, Senior Vice President, General Counsel & Corporate Secretary, Senior Vice President, Human Resources, and Senior Advisor. The CIO provides regular cybersecurity updates to the Audit Committee of the Board of Directors and the Management Committee. These updates address prevention, detection, mitigation, and remediation of cybersecurity incidents, as well as risks, threats, and the threat landscape.
Cybersecurity Risk Management Positions or Committees Responsible [Flag] true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]
Our Vice President and Chief Information Officer (CIO), who has over two decades of experience in information technology, is responsible for overseeing our cybersecurity program. The CIO oversees an IT Information security team responsible for our overall cybersecurity program. This team is comprised of several IT professionals with varying degrees of cybersecurity experience and is led by our Director – Cybersecurity who has over 30 years of experience in information technology and cybersecurity. The Director – Cybersecurity reports to the CIO, who reports to the Senior Vice President and Chief Financial Officer.
The CIO is a member of the Company’s Risk Management and Compliance Committee (RMCC). The RMCC is comprised of members from the senior leadership team and is responsible for overseeing enterprise-wide risk management across all categories, including cybersecurity. The RMCC is overseen by the Company’s Management Committee, which is comprised of the President and Chief Executive Officer, Senior Vice President and Chief Financial Officer, Senior Vice President, Utility Operations, Senior Vice President, General Counsel & Corporate Secretary, Senior Vice President, Human Resources, and Senior Advisor. The CIO provides regular cybersecurity updates to the Audit Committee of the Board of Directors and the Management Committee. These updates address prevention, detection, mitigation, and remediation of cybersecurity incidents, as well as risks, threats, and the threat landscape.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]
Our Vice President and Chief Information Officer (CIO), who has over two decades of experience in information technology, is responsible for overseeing our cybersecurity program. The CIO oversees an IT Information security team responsible for our overall cybersecurity program. This team is comprised of several IT professionals with varying degrees of cybersecurity experience and is led by our Director – Cybersecurity who has over 30 years of experience in information technology and cybersecurity. The Director – Cybersecurity reports to the CIO, who reports to the Senior Vice President and Chief Financial Officer.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block] The CIO provides regular cybersecurity updates to the Audit Committee of the Board of Directors and the Management Committee. These updates address prevention, detection, mitigation, and remediation of cybersecurity incidents, as well as risks, threats, and the threat landscape.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag] true
v3.25.3
Summary of Significant Accounting Policies (Policies)
12 Months Ended
Sep. 30, 2025
Accounting Policies [Abstract]  
Principles of consolidation The accompanying consolidated financial statements include the accounts of Atmos Energy Corporation and its wholly-owned subsidiaries. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process.
Reclassification Certain reclassifications have been made to prior period amounts to conform to current period presentation.
Use of estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses. The most significant estimates include the allowance for doubtful accounts, unbilled revenues, contingency accruals, pension and postretirement obligations, deferred income taxes, risk management and trading activities, and fair value measurements. Actual results could differ from those estimates.
Regulation Our distribution and pipeline and storage operations are subject to regulation with respect to rates, service, maintenance of accounting records, and various other matters by the respective regulatory authorities in the states in which we operate. Our accounting policies recognize the financial effects of the ratemaking and accounting practices and policies of the various regulatory commissions. 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. The amounts to be recovered or recognized are based upon historical experience and our understanding of the regulations. Further, regulation may impact the period in which revenues or expenses are recognized.
Revenue recognition
Distribution Revenues
Distribution revenues represent the delivery of natural gas to residential, commercial, industrial, and public authority customers at prices based on tariff rates established by regulatory authorities in the states in which we operate. Revenue is recognized and our performance obligation is satisfied over time when natural gas is delivered and simultaneously consumed by our customers. We have elected to use the invoice practical expedient and recognize revenue for volumes delivered that we have the right to invoice our customers. We bill our customers on a monthly cycle basis. Accordingly, we estimate volumes from the last meter read to the balance sheet date and accrue revenue for gas delivered but not yet billed.
In our Texas and Mississippi jurisdictions, we pay franchise fees and gross receipt taxes to operate in these service areas. These franchise fees and gross receipts taxes are required to be paid regardless of our ability to collect from our customers. Accordingly, we account for these amounts on a gross basis in revenue and we record the associated tax expense as a component of taxes, other than income.
Pipeline and Storage Revenues
Pipeline and storage revenues primarily represent the transportation and storage of natural gas on our APT system and the transmission of natural gas through our 21-mile pipeline in Louisiana. APT provides transportation and storage services to our Mid-Tex Division, other third party local distribution companies, and certain industrial customers under tariff rates approved by the RRC. APT also provides certain transportation and storage services to industrial and electric generation customers, as well as marketers and producers, under negotiated rates. Our pipeline in Louisiana is primarily used to aggregate gas supply for our Louisiana Division under a long-term contract and on a more limited basis to third parties. The demand fee charged to our Louisiana Division is subject to regulatory approval by the Louisiana Public Service Commission. We also manage two asset management plans with distribution affiliates of the Company at terms that have been approved by the applicable state regulatory commissions. The performance obligations for these transportation customers are satisfied by means of transporting customer-supplied gas to the designated location. Revenue is recognized and our performance obligation is satisfied over time when natural gas is delivered to the customer. Management determined that these arrangements qualify for the invoice practical expedient for recognizing revenue. For demand fee arrangements, revenue is recognized and our performance obligation is satisfied by standing ready to transport natural gas over the period of each individual month.
Alternative Revenue Program Revenues
In our distribution segment, we have weather-normalization adjustment mechanisms that serve to minimize the effects of weather on our residential and commercial revenues. APT has a regulatory mechanism that requires that we share with its tariffed customers 75% of the difference between the total non-tariffed revenues earned during a test period and a revenue benchmark established by the RRC. With the completion of APT's most recent rate case in December 2023, the revenue benchmark was increased from $69.4 million to $106.9 million. Differences between actual revenues and revenues calculated under these mechanisms adjust the amount billed to customers. These mechanisms are considered to be alternative revenue programs under accounting standards generally accepted in the United States as they are deemed to be contracts between us and our regulator. Accordingly, revenue under these mechanisms are excluded from revenue from contracts with customers.
Purchased gas costs Rates established by regulatory authorities are adjusted for increases and decreases in our purchased gas costs through purchased gas cost adjustment mechanisms. There is no margin generated through purchased gas cost adjustments, but they provide a dollar-for-dollar offset to increases or decreases in our distribution segment’s gas costs. The effects of these purchased gas cost adjustment mechanisms are recorded as deferred gas costs on our consolidated balance sheets.
Cash and cash equivalents We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents.
Restricted cash and cash equivalents Restricted cash and cash equivalents consists of funds that are contractually or legally restricted as to usage or withdrawal and have been presented separately from cash and cash equivalents on our consolidated balance sheets. These funds are used to administer payment of debt service on the Securitized Utility Tariff Bonds as well as certain ongoing costs of Atmos Energy Kansas Securitization I, LLC (AEK).
Accounts receivable and allowance for uncollectible accounts Accounts receivable arise from natural gas sales to residential, commercial, industrial, public authority, and other customers. Our accounts receivable balance includes unbilled amounts which represent a customer’s consumption of gas from the date of the last cycle billing through the last day of the month. The receivable balances are short term and generally do not extend beyond one month.
Credit losses on our accounts receivable are measured using an expected credit loss model over the entire contractual term from the date of initial recognition. To minimize credit risk, we assess the credit worthiness of new customers, require deposits where necessary, assess late fees, pursue collection activities, and disconnect service for nonpayment. After disconnection, accounts are written off when deemed uncollectible. At each reporting period, we assess the allowance for uncollectible accounts based on historical experience, current conditions, and consideration of expected future conditions. Circumstances which could affect our estimates include, but are not limited to, customer credit issues, the level of natural gas prices, customer deposits, and general economic conditions.
Gas stored underground Our gas stored underground is comprised of natural gas injected into storage to support the winter season withdrawals for our distribution operations. The average cost method is used for all of our distribution operations. Gas in storage that is retained as cushion gas to maintain reservoir pressure is classified as property, plant and equipment and is valued at cost.
Securitized intangible asset Our securitized intangible asset is recorded on AEK and represents the Securitized Utility Tariff Property acquired from Atmos Energy in fiscal 2023. See Note 10 to the consolidated financial statements. The securitized intangible asset is stated at cost, net of accumulated amortization, and is amortized over the life of the asset in proportion to the pattern of economic benefit based on expected future undiscounted cash flows. At the end of its life, this securitized intangible asset will have no residual value.
Property, plant and equipment Regulated property, plant and equipment is stated at original cost, net of contributions in aid of construction. The cost of additions includes direct construction costs, payroll related costs (taxes, the service cost portion of pension expense and other benefits), administrative and general costs, and an allowance for funds used during construction (AFUDC). AFUDC represents the capitalizable total cost of funds used to finance the construction of major projects.
Major renewals, including replacement pipe, and betterments that are recoverable through our regulatory rate base are capitalized while the costs of maintenance and repairs that are not capitalizable are charged to expense as incurred. The costs of large projects are accumulated in construction in progress until the project is completed. When the project is completed, tested, and placed in service, the balance is transferred to the regulated plant in service account included in the rate base and depreciation begins.
Regulated property, plant and equipment is depreciated at various rates on a straight-line basis. These rates are approved by our regulatory commissions and are comprised of two components: one based on average service life and one based on cost of removal. Accordingly, we recognize our cost of removal expense as a component of depreciation expense. The related cost of removal accrual is reflected as a regulatory liability on the consolidated balance sheet. At the time property, plant and equipment is retired, removal expenses less salvage, are charged to the regulatory cost of removal accrual. The composite depreciation rate was 2.8 percent for the fiscal year ended September 30, 2025, 2.9 percent for the fiscal year ended September 30, 2024, and 3.0 percent for the fiscal year ended September 30, 2023.
Other property, plant and equipment is stated at cost. Depreciation is generally computed on the straight-line method for financial reporting purposes based upon estimated useful lives.
Impairment of long-lived assets We evaluate whether events or circumstances have occurred that indicate that other long-lived assets may not be recoverable or that the remaining useful life may warrant revision. When such events or circumstances are present, we assess the recoverability of long-lived assets by determining whether the carrying value will be recovered through the expected future cash flows. In the event the sum of the expected future cash flows resulting from the use of the asset is less than the carrying value of the asset, an impairment loss equal to the excess of the asset’s carrying value over its fair value is recorded. No impairment losses were recorded for our long-lived assets during the fiscal years ended September 30, 2025, 2024, and 2023.
Goodwill We annually evaluate our goodwill balances for impairment during our second fiscal quarter or more frequently as impairment indicators arise. During the second quarter of fiscal 2025, we completed our annual goodwill impairment assessment. We test goodwill for 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. Although not applicable for the fiscal 2025 analysis, if a qualitative goodwill assessment resulted in impairment indicators, we would then use a present value technique based on discounted cash flows to estimate the fair value of our reporting units. These calculations are dependent on several subjective factors including the timing of future cash flows, future growth rates, and the discount rate. An impairment charge is recognized if the carrying value of a reporting unit’s goodwill exceeds its fair value.
Lease accounting We determine if an arrangement is a lease at the inception of the agreement based on the terms and conditions in the contract. A contract contains a lease if there is an identified asset and we have the right to control the asset. We are the lessee for substantially all of our leasing activities, which primarily includes operating leases for office and warehouse space, tower space, vehicles, and heavy equipment used in our operations. We are also a lessee in finance leases for certain service centers.
We record a lease liability and a corresponding right of use (ROU) asset for all of our leases with a term greater than 12 months. For lease contracts containing renewal and termination options, we include the option period in the lease term when it is reasonably certain the option will be exercised. We most frequently assume renewal options at the inception of the arrangement for our tower and fleet leases, based on our anticipated use of the assets. Real estate leases that contain a renewal option are evaluated on a lease-by-lease basis to determine if the option period should be included in the lease term. Currently, we have not included material renewal options for real estate leases in our ROU asset or lease liability.
The lease liability represents the present value of all lease payments over the lease term. We do not include short-term leases in the calculation of our lease liabilities. The discount rate used to determine the present value of the lease liability is the rate implicit in the lease unless that rate cannot be readily determined. We use the implicit rate stated in the agreement to determine the lease liability for our fleet leases. We use our corporate collateralized incremental borrowing rate as the discount rate for all other lease agreements. This rate is appropriate because we believe it represents the rate we would have incurred to borrow funds to acquire the leased asset over a similar term. We calculated this rate using a combination of inputs, including our current credit rating, quoted market prices of interest rates for our publicly traded unsecured debt, observable market yield curve data for peer companies with a credit rating one notch higher than our current credit rating, and the lease term.
The ROU asset represents the right to use the underlying asset for the lease term, and is equal to the lease liability, adjusted for prepaid or accrued lease payments and any lease incentives that have been paid to us or when we are reasonably certain to incur costs equal to or greater than the allowance defined in the contract. We bundle our lease and non-lease components as a single component for all asset classes.
Variable payments included in our leasing arrangements are expensed in the period in which the obligation for these payments is incurred. Variable payments are dependent on usage, output or may vary for other reasons. Most of our variable lease expense is related to tower leases that have escalating payments based on changes to a stated CPI index, and usage of certain office equipment.
We have not provided material residual value guarantees for our leases, nor do our leases contain material restrictions or covenants.
We utilize operating leases for office and warehouse space, tower space, vehicles, and heavy equipment used in our operations. We also have finance leases for certain build-to-suit service centers.
Marketable securities As of September 30, 2025, we hold marketable securities classified as either equity or debt securities. Changes in fair value of our equity securities are recorded in net income, while debt securities, which are considered available-for-sale securities, are reported at market value with unrealized gains and losses shown as a component of accumulated other comprehensive income (loss).
We regularly evaluate the performance of our available-for-sale debt securities on an investment by investment basis for impairment, taking into consideration the securities’ purpose, volatility, and current returns. If a determination is made that a security will likely be sold before the recovery of its cost, the related investment is written down to its estimated fair value.
Financial instruments and hedging activities We use financial instruments to mitigate commodity price risk in our distribution and pipeline and storage segments and to mitigate interest rate risk. The objectives and strategies for using financial instruments have been tailored to our business and are discussed in Note 16 to the consolidated financial statements.
We record all of our financial instruments on the balance sheet at fair value, with the exception of normal purchases and normal sales that are expected to result in physical delivery, with changes in fair value ultimately recorded in the statement of comprehensive income. These financial instruments are reported as risk management assets and liabilities and are classified as current or noncurrent other assets or liabilities based upon the anticipated settlement date of the underlying financial instrument. We record the cash flow impact of our financial instruments in operating cash flows based upon their balance sheet classification.
The timing of when changes in fair value of our financial instruments are recorded in the statement of comprehensive income depends on whether the financial instrument has been designated and qualifies as a part of a hedging relationship or if regulatory rulings require a different accounting treatment. Changes in fair value for financial instruments that do not meet one of these criteria are recognized in the statement of comprehensive income as they occur.
Financial Instruments Associated with Commodity Price Risk
In our distribution segment, the costs associated with and the realized gains and losses arising from the use of financial instruments to mitigate commodity price risk are included in our purchased gas cost adjustment mechanisms in accordance with regulatory requirements. Therefore, changes in the fair value of these financial instruments are initially recorded as a component of deferred gas costs and recognized in the consolidated statements of comprehensive income as a component of purchased gas cost when the related costs are recovered through our rates and recognized in revenue in accordance with accounting principles generally accepted in the United States. Accordingly, there is no earnings impact on our distribution segment as a result of the use of these financial instruments.
Financial Instruments Associated with Interest Rate Risk
In connection with the planned issuance of long-term debt, we may use financial instruments to manage interest rate risk. We currently manage this risk through the use of forward starting interest rate swaps to fix the Treasury yield component of the interest cost associated with anticipated financings. We designate these financial instruments as cash flow hedges at the time the agreements are executed. Unrealized gains and losses associated with the instruments are recorded as a component of accumulated other comprehensive income (loss). When the instruments settle, the realized gain or loss is recorded as a component of accumulated other comprehensive income (loss) and recognized as a component of interest charges over the life of the related financing arrangement.
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 primarily use quoted market prices and other observable market pricing information in valuing our financial assets and liabilities and minimize the use of unobservable pricing inputs in our measurements.
Fair-value estimates also consider our own creditworthiness and the creditworthiness of the counterparties involved. Our counterparties consist primarily of financial institutions and major energy companies. This concentration of counterparties may materially impact our exposure to credit risk resulting from market, economic, or regulatory conditions. We seek to minimize counterparty credit risk through an evaluation of their financial condition and credit ratings and the use of collateral requirements under certain circumstances.
Amounts reported at fair value are subject to potentially significant volatility based upon changes in market prices, including, but not limited to, the valuation of the portfolio of our contracts, maturity, and settlement of these contracts and newly originated transactions and interest rates, each of which directly affect the estimated fair value of our financial instruments. We believe the market prices and models used to value these financial instruments represent the best information available with respect to closing exchange and over-the-counter quotations, time value, and volatility factors underlying the contracts. Values are adjusted to reflect the potential impact of an orderly liquidation of our positions over a reasonable period of time under then current market conditions.
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) and the lowest priority given to unobservable inputs (Level 3). The levels of the hierarchy are described below:
Level 1 — Represents unadjusted quoted prices in active markets for identical assets or liabilities. An active market for the asset or liability is defined as a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Prices actively quoted on national exchanges are used to determine the fair value of most of our assets and liabilities recorded on our balance sheet at fair value.
Our Level 1 measurements consist primarily of our debt and equity securities. The Level 1 measurements for investments in the Atmos Energy Corporation Master Retirement Trust (the Master Trust), Supplemental Executive Benefit Plan, and postretirement benefit plan consist primarily of exchange-traded financial instruments.
Level 2 — Represents pricing inputs other than quoted prices included in Level 1 that are either directly or indirectly observable for the asset or liability as of the reporting date. These inputs are derived principally from, or corroborated by, observable market data. Our Level 2 measurements primarily consist of non-exchange-traded financial instruments, such as over-the-counter options and swaps and municipal and corporate bonds where market data for pricing is observable. The Level
2 measurements for investments in our Master Trust, Supplemental Executive Benefit Plan, and postretirement benefit plan consist primarily of non-exchange traded financial instruments such as corporate bonds and government securities.
Level 3 — Represents generally unobservable pricing inputs which are developed based on the best information available, including our own internal data, in situations where there is little if any market activity for the asset or liability at the measurement date. The pricing inputs utilized reflect what a market participant would use to determine fair value. We currently do not have any Level 3 investments.
Pension and other postretirement plans Pension and other postretirement plan costs and liabilities are determined on an actuarial basis and are affected by numerous assumptions and estimates including the market value of plan assets, estimates of the expected return on plan assets, assumed discount rates, and current demographic and actuarial mortality data. Our measurement date is September 30. The assumed discount rate and the expected return are the assumptions that generally have the most significant impact on our pension costs and liabilities. The assumed discount rate, the assumed health care cost trend rate, and assumed rates of retirement generally have the most significant impact on our postretirement plan costs and liabilities.
The discount rate is utilized principally in calculating the actuarial present value of our pension and postretirement obligation and net pension and postretirement cost. When establishing our discount rate, we consider high quality corporate bond rates based on bonds available in the marketplace that are suitable for settling the obligations, changes in those rates from the prior year, and the implied discount rate that is derived from matching our projected benefit disbursements with currently available high quality corporate bonds.
The expected long-term rate of return on assets is utilized in calculating the expected return on plan assets component of the annual pension and postretirement plan cost. We estimate the expected return on plan assets by evaluating expected bond returns, equity risk premiums, asset allocations, the effects of active plan management, the impact of periodic plan asset rebalancing, and historical performance. We also consider the guidance from our investment advisors when making a final determination of our expected rate of return on assets. To the extent the actual rate of return on assets realized over the course of a year is greater than or less than the assumed rate, that year’s annual pension or postretirement plan cost is not affected. Rather, this gain or loss is amortized over the expected future working lifetime of the plan participants.
The expected return on plan assets is then calculated by applying the expected long-term rate of return on plan assets to the market-related value of the plan assets. The market-related value of our plan assets represents the fair market value of the plan assets, adjusted to smooth out short-term market fluctuations over a five-year period. The use of this calculation will delay the impact of current market fluctuations on the pension expense for the period.
We use a corridor approach to amortize actuarial gains and losses. Under this approach, net gains or losses in excess of ten percent of the larger of the pension benefit obligation or the market-related value of the assets are amortized on a straight-line basis. The period of amortization is the average remaining service of active participants who are expected to receive benefits under the plan.
We estimate the assumed health care cost trend rate used in determining our annual postretirement net cost based upon our actual health care cost experience, the effects of recently enacted legislation, and general economic conditions. Our assumed rate of retirement is estimated based upon the annual review of our participant census information as of the measurement date.
We present only the current service cost component of the net benefit cost within operations and maintenance expense in the consolidated statements of comprehensive income. The remaining components of net benefit cost are recorded in other non-operating income (expense) in our consolidated statements of comprehensive income. Only the service cost component of net benefit cost is eligible for capitalization and we continue to capitalize these costs into property, plant and equipment. Additionally, we defer into a regulatory asset or liability the portion of non-service components of net periodic benefit cost that are capitalizable for regulatory purposes.
Income taxes Income taxes are determined based on the liability method, which results in income tax assets and liabilities arising from temporary differences. Temporary differences are differences between the tax bases of assets and liabilities and their reported amounts in the financial statements that will result in taxable or deductible amounts in future years. The liability method requires the effect of tax rate changes on accumulated deferred income taxes to be reflected in the period in which the rate change was enacted. The liability method also requires that deferred tax assets be reduced by a valuation allowance unless it is more likely than not that the assets will be realized.
The Company may recognize the tax benefit from uncertain tax positions only if it is at least more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon settlement with the taxing authorities. We recognize accrued interest
related to unrecognized tax benefits as a component of interest charges. We recognize penalties related to unrecognized tax benefits as a component of miscellaneous income (expense) in accordance with regulatory requirements.
Tax collections We are allowed to recover from customers revenue-related taxes that are imposed upon us. We record such taxes as operating expenses and record the corresponding customer charges as operating revenues. However, we do collect and remit various other taxes on behalf of various governmental authorities, and we record these amounts in our consolidated balance sheets on a net basis. We do not collect income taxes from our customers on behalf of governmental authorities.
Contingencies In the normal course of business, we are confronted with issues or events that may result in a contingent liability. These generally relate to lawsuits, claims made by third parties, or the action of various regulatory agencies. For such matters, we record liabilities when they are considered probable and estimable, based on currently available facts and our estimates of the ultimate outcome or resolution of the liability in the future. We maintain liability insurance for various risks associated with the operation of our natural gas pipelines and facilities, including for property damage and bodily injury. These liability insurance policies generally require us to be responsible for the first $1.0 million (self-insured retention) of each incident. To the extent a loss contingency exceeds the self-insurance retention, we record an insurance receivable when recovery is considered probable. Upon reaching a settlement, the loss contingency is deemed resolved and recorded in accounts payable and accrued liabilities until paid. Loss contingencies and any related insurance recovery receivables reflect our best estimate of these amounts as of the date of this report. Actual results may differ from estimates, depending on actual outcomes or changes in the facts or expectations surrounding each potential exposure.
Asset retirement obligations
We record a liability at fair value for an asset retirement obligation when the legal obligation to retire the asset has been incurred with an offsetting increase to the carrying value of the related asset. We believe we have a legal obligation to retire our natural gas storage facilities. However, we have not recognized an asset retirement obligation associated with our storage facilities because we are not able to determine the settlement date of this obligation as we do not anticipate taking our storage facilities out of service permanently. Therefore, we cannot reasonably estimate the fair value of this obligation.
Subsequent events Except as noted in Note 7 and Note 8 to the consolidated financial statements regarding the execution of a new lease and the public offering of senior notes, no events occurred subsequent to the balance sheet date that would require recognition or disclosure in the consolidated financial statements.
Recent accounting pronouncements
In November 2023, the Financial Accounting Standards Board (FASB) issued guidance which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. We adopted this amendment as of September 30, 2025 and applied it retrospectively for all periods presented. See Note 4 for further discussion.
In December 2023, the FASB issued guidance which provides qualitative and quantitative updates to the rate reconciliation and income taxes paid disclosures, among others, in order to enhance the transparency of income tax disclosures, including consistent categories and greater disaggregation of information in the rate reconciliation and disaggregation by jurisdiction of income taxes paid. We early adopted this amendment as of September 30, 2025 and applied it retrospectively for all periods presented. See Note 15 for further discussion.
Accounting pronouncements that will be effective after fiscal 2025
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 reporting periods 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.
Segment Information
As of September 30, 2025, we manage and review our consolidated operations through the following two 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.
Our determination of reportable segments considers the strategic operating units under which we manage sales of various products and services to customers. Although our distribution segment operations are geographically dispersed, they are aggregated and reported as a single segment as each natural gas distribution division has similar economic characteristics. In
addition, because the pipeline and storage operations of our Atmos Pipeline-Texas division and our natural gas transmission operations in Louisiana have similar economic characteristics, they have been aggregated and reported as a single segment.
The accounting policies of the segments are the same as those described in the summary of significant accounting policies. We evaluate performance based on net income or loss of the respective operating units. We allocate interest and pension expense to the pipeline and storage segment; however, there is no debt or pension liability recorded on the pipeline and storage segment balance sheet. All material intercompany transactions have been eliminated; however, we have not eliminated intercompany profits when such amounts are probable of recovery under the affiliates’ rate regulation process. Income taxes are allocated to each segment as if each segment’s income taxes were calculated on a separate return basis.
Our Chief Operating Decision Maker (CODM), the Chief Executive Officer, evaluates performance for each reportable segment based on net income, which is used to help inform the allocation of resources as part of the Company's process for budgeting and monitoring financial performance.
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.
v3.25.3
Nature of Business (Tables)
12 Months Ended
Sep. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Divisions and Service Areas Through our distribution business, we deliver 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 in the service areas described below:
Division  Service Area
Atmos Energy Colorado-Kansas Division  Colorado, Kansas
Atmos Energy Kentucky/Mid-States Division  Kentucky, Tennessee, Virginia
Atmos Energy Louisiana Division  Louisiana
Atmos Energy Mid-Tex Division  Texas, including the Dallas/Fort Worth metropolitan area
Atmos Energy Mississippi Division  Mississippi
Atmos Energy West Texas Division  West Texas
v3.25.3
Summary of Significant Accounting Policies (Tables)
12 Months Ended
Sep. 30, 2025
Accounting Policies [Abstract]  
Schedule of Capitalization
The following table details amounts capitalized for the fiscal year ended September 30.
202520242023
Component of AFUDCStatement of Comprehensive Income Location(In thousands)
DebtInterest charges$21,104 $14,655 $15,808 
EquityOther non-operating income75,425 58,234 64,019 
$96,529 $72,889 $79,827 
v3.25.3
Regulation (Tables)
12 Months Ended
Sep. 30, 2025
Regulated Operations [Abstract]  
Schedule of Regulatory Assets Significant regulatory assets and liabilities as of September 30, 2025 and 2024 included the following:
 September 30
 20252024
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$262 $11,243 
Infrastructure mechanisms (1)
314,047 246,734 
Winter Storm Uri incremental costs5,841 10,373 
Deferred gas costs140,626 159,762 
Regulatory excess deferred taxes (2)
49,793 51,380 
Recoverable loss on reacquired debt2,903 3,070 
Deferred pipeline record collection costs39,035 41,742 
System Safety and Integrity Riders (3)
43,625 38,632 
Other12,597 16,454 
$608,729 $579,390 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$190,274 $257,001 
Regulatory cost of removal obligation641,019 607,032 
Deferred gas costs6,879 9,142 
APT annual adjustment mechanism99,393 73,119 
Pension and postretirement benefit costs291,351 247,250 
Other40,732 34,338 
$1,269,648 $1,227,882 

(1)Infrastructure mechanisms in Texas, Louisiana, and Tennessee allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered 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 Notes 13 and 15 to the 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 Significant regulatory assets and liabilities as of September 30, 2025 and 2024 included the following:
 September 30
 20252024
 (In thousands)
Regulatory assets:
Pension and postretirement benefit costs$262 $11,243 
Infrastructure mechanisms (1)
314,047 246,734 
Winter Storm Uri incremental costs5,841 10,373 
Deferred gas costs140,626 159,762 
Regulatory excess deferred taxes (2)
49,793 51,380 
Recoverable loss on reacquired debt2,903 3,070 
Deferred pipeline record collection costs39,035 41,742 
System Safety and Integrity Riders (3)
43,625 38,632 
Other12,597 16,454 
$608,729 $579,390 
Regulatory liabilities:
Regulatory excess deferred taxes (2)
$190,274 $257,001 
Regulatory cost of removal obligation641,019 607,032 
Deferred gas costs6,879 9,142 
APT annual adjustment mechanism99,393 73,119 
Pension and postretirement benefit costs291,351 247,250 
Other40,732 34,338 
$1,269,648 $1,227,882 

(1)Infrastructure mechanisms in Texas, Louisiana, and Tennessee allow for the deferral of all eligible expenses associated with capital expenditures incurred pursuant to these rules, including the recording of interest on the deferred expenses until the next rate proceeding (rate case or annual rate filing), at which time investment and costs would be recovered 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 Notes 13 and 15 to the 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.
v3.25.3
Segment Information (Tables)
12 Months Ended
Sep. 30, 2025
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment
Income statement information and capital expenditures by segment are shown in the following tables.
 Year Ended September 30, 2025
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Operating revenues from external parties$4,422,355 $280,400 $4,702,755 
Intersegment revenues3,042 784,900 787,942 
Total operating revenues4,425,397 1,065,300 5,490,697 
Operation and maintenance expense644,924 229,986 874,910 
Depreciation and amortization expense (2)
543,840 190,905 734,745 
Interest charges (2)
99,226 72,452 171,678 
Income tax expense (2)
150,961 128,319 279,280 
Other segment items (1)
2,239,665 (8,335)2,231,330 
Net income (2)
$746,781 $451,973 $1,198,754 
Capital expenditures (2)
$2,662,703 $898,696 $3,561,399 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$5,490,697 
Elimination of intersegment revenues(787,942)
Consolidated total operating revenues$4,702,755 
 Year Ended September 30, 2024
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Operating revenues from external parties$3,912,134 $253,053 $4,165,187 
Intersegment revenues3,007 684,976 687,983 
Total operating revenues3,915,141 938,029 4,853,170 
Operation and maintenance expense589,864 218,571 808,435 
Depreciation and amortization expense (2)
491,982 177,990 669,972 
Interest charges (2)
117,086 73,546 190,632 
Income tax expense (2)
96,041 96,840 192,881 
Other segment items (1)
1,948,755 (400)1,948,355 
Net income (2)
$671,413 $371,482 $1,042,895 
Capital expenditures (2)
$2,249,280 $687,844 $2,937,124 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,853,170 
Elimination of intersegment revenues(687,983)
Consolidated total operating revenues$4,165,187 

 Year Ended September 30, 2023
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Operating revenues from external parties$4,096,661 $178,696 $4,275,357 
Intersegment revenues3,029 606,478 609,507 
Total operating revenues4,099,690 785,174 4,884,864 
Operation and maintenance expense543,078 200,580 743,658 
Depreciation and amortization expense (2)
434,721 169,606 604,327 
Interest charges (2)
77,185 60,096 137,281 
Income tax expense (2)
60,032 53,747 113,779 
Other segment items (1)
2,404,277 (4,320)2,399,957 
Net income (2)
$580,397 $305,465 $885,862 
Capital expenditures (2)
$1,927,125 $878,848 $2,805,973 
Reconciliation to consolidated total operating revenues:
Total operating revenues of reportable segments$4,884,864 
Elimination of intersegment revenues(609,507)
Consolidated total operating revenues$4,275,357 
(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 reconcile to consolidated totals.
Balance sheet information at September 30, 2025 and 2024 by segment is presented in the following tables.
 September 30, 2025
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Property, plant and equipment, net (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 

 September 30, 2024
 DistributionPipeline and StorageTotal of Reportable Segments
 (In thousands)
Property, plant and equipment, net (1)
$16,372,659 $5,831,708 $22,204,367 
Total assets$24,328,877 $6,181,558 $30,510,435 
Reconciliation to consolidated assets:
Total assets of reportable segments$30,510,435 
Elimination of intersegment assets(5,315,970)
Consolidated total assets$25,194,465 
(1)The total of reportable segments for this item reconciles to consolidated total.
Schedule of Revenue from External Customers by Products and Services
The following table summarizes our revenues from external parties, excluding intersegment revenues, by products and services for the fiscal years ended September 30.
202520242023
 (In thousands)
Distribution revenues:
Gas sales revenues:
Residential$2,916,245 $2,583,681 $2,638,689 
Commercial1,154,591 1,016,675 1,112,236 
Industrial122,576 100,596 151,970 
Public authority and other52,606 52,180 62,476 
Total gas sales revenues4,246,018 3,753,132 3,965,371 
Transportation revenues149,853 132,608 119,371 
Other gas revenues26,484 26,394 11,919 
Total distribution revenues4,422,355 3,912,134 4,096,661 
Pipeline and storage revenues280,400 253,053 178,696 
Total operating revenues$4,702,755 $4,165,187 $4,275,357 
v3.25.3
Earnings Per Share (Tables)
12 Months Ended
Sep. 30, 2025
Earnings Per Share [Abstract]  
Schedule of Earnings Per Share, Basic and Diluted
Basic and diluted earnings per share for the fiscal years ended September 30 are calculated as follows:
202520242023
 (In thousands, except per share data)
Basic Earnings Per Share
Net income$1,198,754 $1,042,895 $885,862 
Less: Income allocated to participating securities487 553 542 
Net income available to common shareholders$1,198,267 $1,042,342 $885,320 
Basic weighted average shares outstanding158,943 152,508 145,121 
Net income per share — Basic$7.54 $6.83 $6.10 
Diluted Earnings Per Share
Net income available to common shareholders$1,198,267 $1,042,342 $885,320 
Effect of dilutive shares— — — 
Net income available to common shareholders$1,198,267 $1,042,342 $885,320 
Basic weighted average shares outstanding158,943 152,508 145,121 
Dilutive shares1,630 158 45 
Diluted weighted average shares outstanding160,573 152,666 145,166 
Net income per share — Diluted$7.46 $6.83 $6.10 
v3.25.3
Revenue and Accounts Receivable (Tables)
12 Months Ended
Sep. 30, 2025
Revenue from Contract with Customer [Abstract]  
Schedule of Disaggregation of Revenue
The following tables disaggregates our revenue from contracts with customers by customer type and segment and provides a reconciliation to total operating revenues, including intersegment revenues, for the periods presented.
Year Ended September 30, 2025
DistributionPipeline and Storage
(In thousands)
Gas sales revenues:
Residential$2,877,456 $— 
Commercial1,145,710 — 
Industrial122,284 — 
Public authority and other51,354 — 
Total gas sales revenues4,196,804 — 
Transportation revenues151,876 1,119,015 
Miscellaneous revenues13,123 12,749 
Revenues from contracts with customers4,361,803 1,131,764 
Alternative revenue program revenues49,215 (66,464)
Other revenues14,379 — 
Total operating revenues$4,425,397 $1,065,300 
Year Ended September 30, 2024
DistributionPipeline and Storage
Gas sales revenues:
Residential$2,542,438 $— 
Commercial1,006,593 — 
Industrial100,363 — 
Public authority and other51,337 — 
Total gas sales revenues3,700,731 — 
Transportation revenues134,600 982,795 
Miscellaneous revenues11,836 15,892 
Revenues from contracts with customers3,847,167 998,687 
Alternative revenue program revenues52,401 (60,658)
Other revenues15,573 — 
Total operating revenues$3,915,141 $938,029 
Year Ended September 30, 2023
DistributionPipeline and Storage
Gas sales revenues:
Residential$2,606,658 $— 
Commercial1,100,773 — 
Industrial151,538 — 
Public authority and other61,345 — 
Total gas sales revenues3,920,314 — 
Transportation revenues121,420 811,968 
Miscellaneous revenues10,044 12,180 
Revenues from contracts with customers4,051,778 824,148 
Alternative revenue program revenues43,139 (38,974)
Other revenues4,773 — 
Total operating revenues$4,099,690 $785,174 
Schedule of Allowance for Credit Loss Activity
Rollforwards of our allowance for uncollectible accounts for the years ended September 30, 2025, 2024, and 2023 are presented in the table below.
We actively work with our customers experiencing financial hardship to offer flexible payment options and to direct them to aid agencies for financial assistance. Our allowance for uncollectible accounts reflects the expected impact on our customers’ ability to pay. Our allowance for uncollectible accounts also reflects the fact that we have the ability to recover the gas cost portion of uncollectible accounts through our gas cost recovery mechanisms in six states, which covers approximately 89 percent of our residential and commercial customers.
In December 2023, the Mississippi Public Service Commission approved the recovery of uncollectible accounts through our purchased gas cost mechanism over a two-year period rather than through our annual filing mechanism over a one-year period. As a result of this decision, we recorded a $13.9 million reduction to bad debt expense during the first quarter of fiscal
2024. Of this amount, $9.7 million represents future recovery of customer receivables previously written off since April 2022 but not yet recovered through our rates. This amount increased our deferred gas cost regulatory asset. The remaining $4.2 million reduction represents a reversal of our allowance for uncollectible accounts for customer balances that have not yet been written off.
 Allowance for uncollectible accounts
 (In thousands)
Balance, September 30, 2022
$49,993 
Current period provisions22,353 
Write-offs charged against allowance(33,595)
Recoveries of amounts previously written off2,089 
Balance, September 30, 2023
40,840 
Current period provisions24,843 
Write-offs charged against allowance(26,165)
Recoveries of amounts previously written off1,730 
Mississippi recovery of uncollectible accounts(4,192)
Balance, September 30, 2024
37,056 
Current period provisions30,778 
Write-offs charged against allowance(24,631)
Recoveries of amounts previously written off2,056 
Balance, September 30, 2025
$45,259 
v3.25.3
Leases (Tables)
12 Months Ended
Sep. 30, 2025
Leases [Abstract]  
Schedule of Other Pertinent Information Related to Leases
The following table presents our weighted average remaining lease term for our leases.
September 30, 2025September 30, 2024
Weighted average remaining lease term (years)
Finance leases15.716.7
Operating leases8.89.9
The following table represents our weighted average discount rate:
September 30, 2025September 30, 2024
Weighted average discount rate
Finance leases4.0 %4.0 %
Operating leases4.5 %4.1 %
Lease costs for the years ended September 30, 2025, 2024, and 2023 are presented in the table below. These costs include both amounts recognized in expense and amounts capitalized. For the years ended September 30, 2025, 2024, and 2023 we did not have material short-term lease costs or variable lease costs.
Year Ended September 30
202520242023
(In thousands)
Finance lease cost$4,467 $4,523 $4,499 
Operating lease cost56,695 48,421 44,090 
Total lease cost$61,162 $52,944 $48,589 
Our ROU assets and lease liabilities are presented as follows on the consolidated balance sheets:
Balance Sheet ClassificationSeptember 30, 2025September 30, 2024
(In thousands)
Assets
Finance leasesNet property, plant and equipment$42,064 $44,748 
Operating leasesDeferred charges and other assets293,934 249,556 
Total right-of-use assets$335,998 $294,304 
Liabilities
Current
Finance leasesCurrent maturities of long-term debt$1,775 $1,651 
Operating leasesOther current liabilities45,010 34,340 
Noncurrent
Finance leasesLong-term debt45,459 47,239 
Operating leasesDeferred credits and other liabilities262,549 224,498 
Total lease liabilities$354,793 $307,728 
Other pertinent information related to leases was as follows. During the years ended September 30, 2025, 2024, and 2023 amounts paid in cash for our finance leases were not material.
Year Ended September 30
202520242023
(In thousands)
Cash paid amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases$52,528 $47,069 $45,463 
Right-of-use assets obtained in exchange for lease obligations
Finance leases$— $— $— 
Operating leases$89,598 $65,672 $29,976 
Schedule of Finance Lease Liability Maturities
Maturities of our lease liabilities as of September 30, 2025 were as follows by fiscal years:
TotalFinance LeasesOperating Leases
(In thousands)
2026$60,048 $3,502 $56,546 
202755,881 3,568 52,313 
202850,775 3,635 47,140 
202944,304 3,703 40,601 
203038,240 3,782 34,458 
Thereafter189,621 44,877 144,744 
Total lease payments438,869 63,067 375,802 
Less: Imputed interest84,076 15,833 68,243 
Total$354,793 $47,234 $307,559 
Reported as of September 30, 2025
Short-term lease liabilities$46,785 $1,775 $45,010 
Long-term lease liabilities308,008 45,459 262,549 
Total lease liabilities$354,793 $47,234 $307,559 
Schedule of Operating Lease Liability Maturities
Maturities of our lease liabilities as of September 30, 2025 were as follows by fiscal years:
TotalFinance LeasesOperating Leases
(In thousands)
2026$60,048 $3,502 $56,546 
202755,881 3,568 52,313 
202850,775 3,635 47,140 
202944,304 3,703 40,601 
203038,240 3,782 34,458 
Thereafter189,621 44,877 144,744 
Total lease payments438,869 63,067 375,802 
Less: Imputed interest84,076 15,833 68,243 
Total$354,793 $47,234 $307,559 
Reported as of September 30, 2025
Short-term lease liabilities$46,785 $1,775 $45,010 
Long-term lease liabilities308,008 45,459 262,549 
Total lease liabilities$354,793 $47,234 $307,559 
v3.25.3
Debt (Tables)
12 Months Ended
Sep. 30, 2025
Debt Disclosure [Abstract]  
Schedule of Long-term Debt Instruments
Long-term debt at September 30, 2025 and 2024 consisted of the following:
20252024
 (In thousands)
Unsecured 3.00% Senior Notes, due June 2027
$500,000 $500,000 
Unsecured 2.625% Senior Notes, due September 2029
500,000 500,000 
Unsecured 1.50% Senior Notes, due January 2031
600,000 600,000 
Unsecured 5.45% Senior Notes, due October 2032
300,000 300,000 
Unsecured 5.90% Senior Notes, due 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 — 
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 — 
Medium term Series A notes, 1995-1, 6.67%, due December 2025
10,000 10,000 
Unsecured 6.75% Debentures, due July 2028
150,000 150,000 
Finance lease obligations (see Note 7)
47,234 48,890 
Total long-term debt8,982,234 7,833,890 
Less:
Net original issue premium on unsecured senior notes and debentures(1,332)(9,071)
Debt issuance cost64,622 57,664 
Current maturities11,775 1,651 
$8,907,169 $7,783,646 
Schedule of Maturities of Long-term Debt
Maturities of long-term debt, excluding our finance lease obligations, at September 30, 2025 were as follows by fiscal years (in thousands):
2026$10,000 
2027500,000 
2028150,000 
2029500,000 
2030— 
Thereafter7,775,000 
$8,935,000 
The following table summarizes the maturities of the securitized long-term debt and the amortization expense related to the securitized intangible asset expected to be recognized in our consolidated statements of comprehensive income:
Maturities of Securitized Long-Term DebtAmortization Expense of Securitized Intangible Asset
For the fiscal year ending:(In thousands)
2026$8,767 $8,555 
20279,086 9,001 
20289,561 9,471 
202910,060 9,966 
203010,585 10,486 
Thereafter28,944 27,648 
Total$77,003 $75,127 
v3.25.3
Shareholders' Equity (Tables)
12 Months Ended
Sep. 30, 2025
Equity [Abstract]  
Schedule of Forward Sales Agreements Additionally, we had $1.6 billion in available proceeds from outstanding forward sale agreements, as detailed below.
MaturityShares AvailableNet Proceeds Available
(In Thousands)
Forward Price
December 31, 20251,160,351$148,610 $128.07 
March 31, 20263,627,033465,210 $128.26 
June 30, 2026669,04389,572 $133.88 
December 31, 20263,392,352475,294 $140.11 
March 31, 20272,477,820379,836 $153.29 
Total11,326,599$1,558,522 $137.60 
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, 2024$213 $465,502 $465,715 
Other comprehensive income (loss) before reclassifications(4)24,208 24,204 
Amounts reclassified from accumulated other comprehensive income— (14,904)(14,904)
Net current-period other comprehensive income (loss)(4)9,304 9,300 
September 30, 2025$209 $474,806 $475,015 
 
Available-
for-Sale
Securities
Interest Rate
Agreement
Cash Flow
Hedges
Total
 (In thousands)
September 30, 2023$(369)$518,897 $518,528 
Other comprehensive income (loss) before reclassifications582 (43,430)(42,848)
Amounts reclassified from accumulated other comprehensive income
— (9,965)(9,965)
Net current-period other comprehensive income (loss)582 (53,395)(52,813)
September 30, 2024$213 $465,502 $465,715 
v3.25.3
Securitization (Tables)
12 Months Ended
Sep. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Condensed Consolidated Balance Sheet
The following table summarizes the impact of AEK on our consolidated balance sheets, for the periods indicated:
September 30, 2025September 30, 2024
 (In thousands)
Restricted cash and cash equivalents$1,116 $1,516 
Other current assets$$
Securitized intangible asset, net$75,127 $82,844 
Accrued interest$331 $365 
Current maturities of securitized long-term debt$8,767 $8,207 
Securitized long-term debt$68,236 $76,871 
Schedule of Condensed Statement of Comprehensive Income
The following table summarizes the impact of AEK on our consolidated statements of comprehensive income, for the periods indicated:
Year Ended September 30
202520242023
 (In thousands)
Operating revenues$12,408 $13,660 $2,743 
Operation and maintenance expense(559)(427)— 
Amortization expense(7,717)(8,715)(1,398)
Interest expense, net(4,132)(4,518)(1,345)
Income before income taxes$— $— $— 
Schedule of Maturities of Long-term Debt
Maturities of long-term debt, excluding our finance lease obligations, at September 30, 2025 were as follows by fiscal years (in thousands):
2026$10,000 
2027500,000 
2028150,000 
2029500,000 
2030— 
Thereafter7,775,000 
$8,935,000 
The following table summarizes the maturities of the securitized long-term debt and the amortization expense related to the securitized intangible asset expected to be recognized in our consolidated statements of comprehensive income:
Maturities of Securitized Long-Term DebtAmortization Expense of Securitized Intangible Asset
For the fiscal year ending:(In thousands)
2026$8,767 $8,555 
20279,086 9,001 
20289,561 9,471 
202910,060 9,966 
203010,585 10,486 
Thereafter28,944 27,648 
Total$77,003 $75,127 
Schedule of Amortization Expense of Securitized Intangible Asset
The following table summarizes the maturities of the securitized long-term debt and the amortization expense related to the securitized intangible asset expected to be recognized in our consolidated statements of comprehensive income:
Maturities of Securitized Long-Term DebtAmortization Expense of Securitized Intangible Asset
For the fiscal year ending:(In thousands)
2026$8,767 $8,555 
20279,086 9,001 
20289,561 9,471 
202910,060 9,966 
203010,585 10,486 
Thereafter28,944 27,648 
Total$77,003 $75,127 
v3.25.3
Retirement and Postretirement Employee Benefit Plans (Tables)
12 Months Ended
Sep. 30, 2025
Retirement Benefits [Abstract]  
Schedule of Net Periodic Benefit Cost Not yet Recognized Additionally, the amounts that have not yet been recognized in net periodic pension cost that have been recorded as regulatory assets or liabilities are as follows:
Employee Pension PlanSupplemental
Executive
Retirement Plans
Postretirement
Plan
Total
 (In thousands)
September 30, 2025
Unrecognized prior service credit$— $— $(9,984)$(9,984)
Unrecognized actuarial (gain) loss(179,351)17,661 (116,690)(278,380)
$(179,351)$17,661 $(126,674)$(288,364)
September 30, 2024
Unrecognized prior service credit$— $— $(24,897)$(24,897)
Unrecognized actuarial (gain) loss(126,989)16,136 (111,500)(222,353)
$(126,989)$16,136 $(136,397)$(247,250)
Schedule of Allocation of Plan Assets
The following table presents asset allocation information for the Master Trust as of September 30, 2025 and 2024.
 Targeted
Allocation  Range
Actual
Allocation
September 30
Security Class20252024
Domestic equities
35%-55%
43.6%42.8%
International equities
10%-20%
15.5%15.8%
Fixed income
5%-45%
24.3%22.3%
Company stock
0%-15%
14.0%16.7%
Other assets
0%-20%
2.6%2.4%
The following table presents asset allocation information for the Retiree Medical Plan assets as of September 30, 2025 and 2024.
 Actual
Allocation
September 30
Security Class20252024
Diversified investment funds98.6%97.8%
Cash and cash equivalents1.4%2.2%
Schedule of Assumptions Used
Additional assumptions are presented in the following table:
 Pension
Asset
Pension Cost
 20252024202520242023
Discount rate5.45 %5.02 %5.02 %6.10 %5.66 %
Rate of compensation increase3.50 %3.50 %3.50 %3.50 %3.50 %
Expected return on plan assets6.50 %6.50 %6.50 %6.25 %6.25 %
Interest crediting rate (1)
4.69 %4.69 %4.69 %4.69 %4.69 %
(1)    The interest crediting rate assumption for the development of the fiscal 2025 pension asset is 4.73% for calendar year 2026, then reverting back to 4.69% for all future years.
These assumptions are presented in the following table:
 Pension
Liability
Pension Cost
 20252024202520242023
Discount rate (1)
5.14 %4.92 %4.92 %5.85 %5.50 %
Rate of compensation increase3.50 %3.50 %3.50 %3.50 %3.50 %
Interest crediting rate (2)
4.69 %4.69 %4.69 %4.69 %4.69 %
 (1)    Reflects a weighted average discount rate for pension cost for fiscal 2024 and 2023 due to the settlements during the year.
 (2)    The interest crediting rate assumption for the development of the fiscal 2025 pension liability is 4.73% for calendar year 2026, then reverting back to 4.69% for all future years.
The assumptions are presented in the following table:
 Postretirement
Asset
Postretirement Cost
 20252024202520242023
Discount rate5.47 %5.01 %5.01 %6.06 %5.61 %
Expected return on plan assets5.14 %5.14 %5.14 %4.94 %4.94 %
Initial trend rate7.00 %6.75 %6.75 %6.50 %6.25 %
Ultimate trend rate5.00 %5.00 %5.00 %5.00 %4.75 %
Ultimate trend reached in20342032203220302029
Schedule of Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan
The following table presents the Pension Plan’s accumulated benefit obligation, projected benefit obligation, and funded status as of September 30, 2025 and 2024:
20252024
 (In thousands)
Accumulated benefit obligation$428,845 $448,353 
Change in projected benefit obligation:
Benefit obligation at beginning of year$470,902 $431,560 
Service cost10,047 9,546 
Interest cost23,164 25,731 
Actuarial (gain) loss(18,133)44,205 
Benefits paid(35,556)(40,140)
Benefit obligation at end of year450,424 470,902 
Change in plan assets:
Fair value of plan assets at beginning of year595,212 502,412 
Actual return on plan assets64,847 127,940 
Employer contributions— 5,000 
Benefits paid(35,556)(40,140)
Fair value of plan assets at end of year624,503 595,212 
Reconciliation:
Funded status174,079 124,310 
Unrecognized prior service cost— — 
Unrecognized net loss— — 
Net amount recognized$174,079 $124,310 
The following table presents the Supplemental Plans’ accumulated benefit obligation, projected benefit obligation, and funded status as of September 30, 2025 and 2024:
20252024
 (In thousands)
Accumulated benefit obligation$73,570 $71,003 
Change in projected benefit obligation:
Benefit obligation at beginning of year$71,944 $75,898 
Service cost1,302 55 
Interest cost3,488 4,024 
Actuarial loss2,547 5,853 
Benefits paid(4,761)(4,285)
Settlements— (9,601)
Benefit obligation at end of year74,520 71,944 
Change in plan assets:
Fair value of plan assets at beginning of year— — 
Employer contribution— — 
Benefits paid— — 
Settlements— — 
Fair value of plan assets at end of year— — 
Reconciliation:
Funded status(74,520)(71,944)
Unrecognized prior service cost— — 
Unrecognized net loss— — 
Accrued pension cost$(74,520)$(71,944)
The following table presents the Retiree Medical Plan’s benefit obligation and funded status as of September 30, 2025 and 2024:
20252024
 (In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year$269,391 $234,004 
Service cost8,132 6,028 
Interest cost13,463 14,034 
Plan participants’ contributions1,993 2,102 
Actuarial (gain) loss(8,733)31,135 
Benefits paid(19,065)(17,912)
Plan amendments1,873 — 
Benefit obligation at end of year267,054 269,391 
Change in plan assets:
Fair value of plan assets at beginning of year300,692 255,800 
Actual return on plan assets21,500 47,857 
Employer contributions— — 
Benefits paid(2,808)(2,965)
Fair value of plan assets at end of year319,384 300,692 
Reconciliation:
Funded status52,330 31,301 
Unrecognized transition obligation— — 
Unrecognized prior service cost— — 
Unrecognized net loss— — 
Accrued postretirement cost$52,330 $31,301 
Schedule of Net Benefit Costs
Net periodic pension cost for the Pension Plan for fiscal 2025, 2024, and 2023 is presented in the following table.
 Fiscal Year Ended September 30
 202520242023
 (In thousands)
Components of net periodic pension cost:
Service cost$10,047 $9,546 $10,805 
Interest cost (1)
23,164 25,731 24,924 
Expected return on assets (1)
(30,618)(28,808)(29,113)
Amortization of prior service credit (1)
— — (121)
Recognized actuarial gain (1)
— (67)— 
Net periodic pension cost$2,593 $6,402 $6,495 

(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 consolidated statements of comprehensive income or are capitalized on the consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements.
Net periodic pension cost for the Supplemental Plans for fiscal 2025, 2024, and 2023 is presented in the following table.
 Fiscal Year Ended September 30
 202520242023
 (In thousands)
Components of net periodic pension cost:
Service cost$1,302 $55 $845 
Interest cost (1)
3,488 4,024 4,227 
Recognized actuarial loss (1)
1,022 501 691 
Settlements (1)
— 1,529 1,030 
Net periodic pension cost$5,812 $6,109 $6,793 

(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 consolidated statements of comprehensive income or are capitalized on the consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements.
Net periodic postretirement cost for the Retiree Medical Plan for fiscal 2025, 2024, and 2023 is presented in the following table.
 Fiscal Year Ended September 30
 202520242023
 (In thousands)
Components of net periodic postretirement cost:
Service cost$8,132 $6,028 $6,183 
Interest cost (1)
13,463 14,034 13,911 
Expected return on assets (1)
(15,325)(12,511)(11,215)
Amortization of prior service credit (1)
(13,040)(13,040)(13,142)
Recognized actuarial gain (1)
(9,716)(10,872)(7,452)
Net periodic postretirement cost$(16,486)$(16,361)$(11,715)

(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 consolidated statements of comprehensive income or are capitalized on the consolidated balance sheets as a regulatory asset or liability, as described in Note 2 to the consolidated financial statements.
Schedule of Employee Pension Plans Investments at Fair Value In addition to the assets shown below, the Pension Plan had net accounts receivable of $5.1 million and $0.7 million at September 30, 2025 and 2024, which materially approximates fair value due to the short-term nature of these assets.
 Assets at Fair Value as of September 30, 2025
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Common stocks$284,573 $— $— $284,573 
Money market funds— 16,293 — 16,293 
Registered investment companies123,022 — — 123,022 
Government securities:
Mortgage-backed securities— 26,101 — 26,101 
U.S. treasuries15,021 26 — 15,047 
Corporate bonds— 32,517 — 32,517 
Asset-backed securities— 1,475 — 1,475 
Total investments measured at fair value$422,616 $76,412 $— 499,028 
Investments measured at net asset value:
Common/collective trusts (1)
95,558 
Limited partnerships (1)
24,843 
Total investments$619,429 

 Assets at Fair Value as of September 30, 2024
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Common stocks$289,301 $— $— $289,301 
Money market funds— 14,542 — 14,542 
Registered investment companies90,086 — — 90,086 
Government securities:
Mortgage-backed securities— 24,383 — 24,383 
U.S. treasuries9,398 27 — 9,425 
Corporate bonds— 31,986 — 31,986 
Total investments measured at fair value$388,785 $70,938 $— 459,723 
Investments measured at net asset value:
Common/collective trusts (1)
111,103 
Limited partnerships (1)
23,665 
Total investments$594,491 
(1)    The fair value of our common/collective trusts and limited partnerships are measured using the net asset value per share practical expedient. There are no redemption restrictions, redemption notice periods, or unfunded commitments for these investments. The redemption frequency is daily.
Schedule of Expected Benefit Payments
The following benefit payments for our defined benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years:
Pension
Plan
Supplemental
Plans
 (In thousands)
2026$40,122 $6,277 
202739,190 9,627 
202838,729 28,392 
202938,798 3,783 
203038,777 3,615 
2031-2035178,831 31,031 
The following benefit payments paid by the Company, retirees, and prescription drug subsidies for our Retiree Medical Plan, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years.
Company
Payments
Retiree
Payments
Subsidy
Payments
Total
Postretirement
Benefits
 (In thousands)
2026$18,898 $2,425 $— $21,323 
202718,859 2,320 — 21,179 
202818,783 2,186 — 20,969 
202919,011 2,112 — 21,123 
203019,364 2,083 — 21,447 
2031-2035104,216 10,770 — 114,986 
Schedule of Postretirement Benefit Plans Investments at Fair Value
The following tables set forth by level, within the fair value hierarchy, the Retiree Medical Plan’s assets at fair value as of September 30, 2025 and 2024. The methods used to determine fair value for the assets held by the Retiree Medical Plan are fully described in Note 2 to the consolidated financial statements.
 Assets at Fair Value as of September 30, 2025
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Money market funds$— $4,428 $— $4,428 
Registered investment companies314,956 — — 314,956 
Total investments measured at fair value$314,956 $4,428 $— $319,384 
 
 Assets at Fair Value as of September 30, 2024
 Level 1Level 2Level 3Total
 (In thousands)
Investments:
Money market funds$— $6,633 $— $6,633 
Registered investment companies294,059 — — 294,059 
Total investments measured at fair value$294,059 $6,633 $— $300,692 
v3.25.3
Stock and Other Compensation Plans (Tables)
12 Months Ended
Sep. 30, 2025
Share-Based Payment Arrangement [Abstract]  
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity
The following summarizes information regarding the restricted stock units granted under the plan during the fiscal years ended September 30, 2025, 2024, and 2023:
 202520242023
 Number of
Restricted
Units
Weighted
Average
Grant-Date
Fair
Value
Number of
Restricted
Units
Weighted
Average
Grant-Date
Fair
Value
Number of
Restricted
Units
Weighted
Average
Grant-Date
Fair
Value
Nonvested at beginning of year397,929 $113.78 389,957 $109.10 381,295 $105.69 
Granted229,828 135.68 212,207 117.11 241,436 109.78 
Vested(215,806)111.75 (201,834)108.56 (220,929)104.05 
Forfeited(3,815)127.58 (2,401)115.44 (11,845)107.47 
Nonvested at end of year408,136 $127.74 397,929 $113.78 389,957 $109.10 
v3.25.3
Details of Selected Financial Statement Captions (Tables)
12 Months Ended
Sep. 30, 2025
Balance Sheet Related Disclosures [Abstract]  
Schedule of Accounts Receivables
Accounts receivable was comprised of the following at September 30, 2025 and 2024:
 September 30
 20252024
 (In thousands)
Billed accounts receivable$213,651 $220,869 
Unbilled revenue140,651 123,550 
Insurance receivable22,940 51,715 
Other accounts receivable43,526 6,804 
Total accounts receivable420,768 402,938 
Less: allowance for uncollectible accounts(45,259)(37,056)
Net accounts receivable$375,509 $365,882 
Schedule of Other Current Assets
Other current assets as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
 (In thousands)
Deferred gas costs$140,626 $159,762 
Winter Storm Uri incremental costs5,841 3,949 
Prepaid expenses80,495 74,780 
Taxes receivable8,948 14,332 
Materials and supplies20,076 16,961 
Assets from risk management activities5,303 2,091 
Regulatory assets (See Note 3)
33,311 12,297 
Other7,027 3,896 
Total$301,627 $288,068 
Schedule of Property, Plant and Equipment
Property, plant and equipment was comprised of the following as of September 30, 2025 and 2024:
 September 30
 20252024
 (In thousands)
Storage plant$790,621 $708,617 
Transmission plant6,308,557 5,713,831 
Distribution plant19,788,099 17,304,207 
General plant1,102,931 1,019,018 
Intangible plant38,612 38,612 
28,028,820 24,784,285 
Construction in progress1,235,316 1,063,798 
29,264,136 25,848,083 
Less: accumulated depreciation and amortization(3,971,146)(3,643,716)
Net property, plant and equipment (1)
$25,292,990 $22,204,367 
    
(1)     Net property, plant and equipment includes plant acquisition adjustments of $(21.1) million and $(22.9) million at September 30, 2025 and 2024.
Schedule of Deferred Charges and Other Assets
Deferred charges and other assets as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
 (In thousands)
Marketable securities$114,938 $110,594 
Regulatory assets (See Note 3)
428,951 396,958 
Operating lease right of use assets (See Note 7)
293,934 249,556 
Winter Storm Uri incremental costs— 6,424 
Assets from risk management activities4,594 94,197 
Pension and postretirement assets226,409 155,611 
Other28,627 30,343 
Total$1,097,453 $1,043,683 
Schedule of Accounts Payable and Accrued Liabilities
Accounts payable and accrued liabilities as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
(In thousands)
Trade accounts payable$380,999 $341,948 
Accrued gas payable37,073 19,125 
Accrued liabilities88,444 84,324 
Total$506,516 $445,397 
Schedule of Other Current Liabilities
Other current liabilities as of September 30, 2025 and 2024 were comprised of the following accounts.
 
 September 30
 20252024
 (In thousands)
Customer credit balances and deposits$56,185 $62,085 
Accrued employee costs69,062 64,141 
Deferred gas costs6,879 9,142 
Operating lease liabilities (See Note 7)
45,010 34,340 
Accrued interest122,459 106,116 
Liabilities from risk management activities6,339 7,324 
Taxes payable237,965 215,857 
Pension and postretirement liabilities6,122 4,622 
Regulatory cost of removal obligation108,558 99,217 
APT annual adjustment mechanism68,094 35,924 
Regulatory excess deferred taxes (See Note 15)
72,792 79,686 
Other36,092 32,166 
Total$835,557 $750,620 
Schedule of Deferred Credits and Other Liabilities
Deferred credits and other liabilities as of September 30, 2025 and 2024 were comprised of the following accounts.
 September 30
 20252024
 (In thousands)
Pension and postretirement liabilities$68,398 $67,322 
Operating lease liabilities (See Note 7)
262,549 224,498 
Customer advances for construction9,573 7,973 
Other regulatory liabilities (See Note 3)
332,017 279,979 
Asset retirement obligation7,428 7,942 
Liabilities from risk management activities146 313 
APT annual adjustment mechanism31,299 37,195 
Unrecognized tax benefits (See Note 15)
50,210 46,174 
Other22,702 20,536 
Total$784,322 $691,932 
Schedule of Other Non-Operating Income
Other non-operating income for the fiscal years ended September 30, 2025, 2024, and 2023 were comprised of the following accounts.
Year Ended September 30
202520242023
(In thousands)
Equity component of AFUDC$75,425 $58,234 $64,019 
Performance-based rate program8,485 8,389 7,093 
Pension and other postretirement non-service credit14,372 10,820 8,955 
Interest income29,944 22,887 7,207 
Community support spending(21,114)(20,016)(12,027)
Unrealized gains on equity securities174 3,562 1,406 
Miscellaneous(17,545)(12,830)(6,878)
Total$89,741 $71,046 $69,775 
Schedule of Supplemental Cash Flow Disclosures
Supplemental disclosures of cash flow information for the fiscal years ended September 30, 2025, 2024, and 2023 were as follows:
 Year Ended September 30
 202520242023
 (In thousands)
Cash Paid (Received) During The Period For:
Interest (1)
$349,222 $308,872 $249,066 
Income taxes:
Federal$(5,000)$8,200 $(4,500)
State of Texas7,095 5,372 17,200 
State of Louisiana2,357 1,739 2,232 
Other states— 38 36 
$4,452 $15,349 $14,968 
Non-Cash Transactions:
Capital expenditures included in current liabilities$327,814 $299,908 $186,912 
(1)    Cash paid during the period for interest, net of amounts capitalized was $155.3 million, $163.5 million, and $117.9 million for the fiscal years ended September 30, 2025, 2024, and 2023.
v3.25.3
Income Taxes (Tables)
12 Months Ended
Sep. 30, 2025
Income Tax Disclosure [Abstract]  
Schedule of Effective Income Tax Rate Reconciliation
Reconciliations of the provision for income taxes computed at the statutory rate of 21 percent to the reported provisions for income taxes from continuing operations for 2025, 2024, and 2023 are set forth below:
202520242023
 (In thousands)%(In thousands)%(In thousands)%
U.S federal statutory tax rate$310,387 21.0 %$259,513 21.0 %$209,925 21.0 %
State and local income taxes, net of federal income tax effect (1)
24,254 1.6 %27,367 2.2 %19,853 2.0 %
Changes in valuation allowances— — %1,106 0.1 %— — %
Changes in unrecognized tax benefits2,004 0.1 %926 0.1 %5,302 0.5 %
Nontaxable or nondeductible items741 0.1 %2,464 0.2 %1,000 0.1 %
Amortization of excess deferred taxes(60,727)(4.1)%(100,270)(8.1)%(123,953)(12.4)%
Other, net2,621 0.2 %1,775 0.1 %1,652 0.2 %
Income tax expense$279,280 18.9 %$192,881 15.6 %$113,779 11.4 %
(1)    The states that contribute to the majority (greater than 50%) of the tax effect in this category include Texas and Louisiana.
Schedule of Deferred Tax Assets and Liabilities The tax effect of temporary differences that gave rise to significant components of the deferred tax liabilities and deferred tax assets at September 30, 2025 and 2024 are presented below:
20252024
 (In thousands)
Deferred tax assets:
Employee benefit plans$34,202 $41,184 
Net operating loss carryforwards473,642 484,816 
Charitable and other credit carryforwards14,200 12,301 
Regulatory excess deferred tax31,387 46,330 
Lease asset72,973 63,747 
Other31,145 34,934 
Total deferred tax assets657,549 683,312 
Valuation allowance(1,365)(1,457)
Net deferred tax assets656,184 681,855 
Deferred tax liabilities:
Difference in net book value and net tax value of assets(3,200,535)(2,914,854)
Gas cost adjustments(43,819)(49,443)
Winter Storm Uri regulatory asset(17,993)(20,846)
Lease liability(66,831)(57,177)
Rate deferral adjustment(64,640)(50,571)
Interest rate agreements(135,640)(134,536)
Other(45,073)(47,770)
Total deferred tax liabilities(3,574,531)(3,275,197)
Net deferred tax liabilities$(2,918,347)$(2,593,342)
Schedule of Unrecognized Tax Benefits The following table reconciles the beginning and ending balance of our unrecognized tax benefits:
202520242023
(In thousands)
Unrecognized tax benefits - beginning balance$57,797 $58,638 $52,683 
Decrease resulting from prior period tax positions(1,759)(2,867)(631)
Decrease resulting from a lapse in statute of limitations(5,699)(6,188)— 
Increase resulting from current period tax positions9,993 8,214 6,586 
Unrecognized tax benefits - ending balance60,332 57,797 58,638 
Less: deferred federal and state income tax benefits(12,670)(12,137)(12,314)
Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year (1)
$47,662 $45,660 $46,324 
(1)    As of September 30, 2025, there is an anticipated $43.3 million regulatory offset and associated impact to tax expense to be recorded upon recognition of unrecognized tax benefits.
v3.25.3
Financial Instruments (Tables)
12 Months Ended
Sep. 30, 2025
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Schedule of Financial Instruments on the Balance Sheet
The following tables present the fair value and balance sheet classification of our financial instruments as of September 30, 2025 and 2024. As discussed in Note 2 to the consolidated financial statements, we report our financial instruments as risk management assets and liabilities, each of which is classified as current or noncurrent based upon the anticipated settlement date of the underlying financial instrument. The gross amounts of recognized assets and liabilities are netted within our consolidated balance sheets to the extent that we have netting arrangements with the counterparties. However, as of September 30, 2025 and 2024, no gross amounts and no cash collateral were netted within our consolidated balance sheet.
Balance Sheet LocationAssetsLiabilities
   (In thousands)
September 30, 2025
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)
 
Balance Sheet LocationAssetsLiabilities
   (In thousands)
September 30, 2024
Designated As Hedges:
Interest rate contractsDeferred charges and other assets /
Deferred credits and other liabilities
$91,981 $— 
Total91,981 — 
Not Designated As Hedges:
Commodity contractsOther current assets /
Other current liabilities
2,091 (7,324)
Commodity contractsDeferred charges and other assets /
Deferred credits and other liabilities
2,216 (313)
Total4,307 (7,637)
Gross / Net Financial Instruments$96,288 $(7,637)
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, net of taxes, for the years ended September 30, 2025 and 2024.
 Fiscal Year Ended
September 30
 20252024
 (In thousands)
Increase (decrease) in fair value:
Interest rate agreements$24,208 $(43,430)
Recognition of gains in earnings due to settlements:
Interest rate agreements(14,904)(9,965)
Total other comprehensive income (loss) from hedging, net of tax$9,304 $(53,395)
Schedule of Expected Recognition in Earnings of the Deferred Net Gains Recorded in AOCI 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.
Interest Rate
Agreements
 (In thousands)
2026$19,093 
202719,093 
202819,093 
202919,093 
203019,093 
Thereafter379,341 
Total$474,806 
v3.25.3
Fair Value Measurements (Tables)
12 Months Ended
Sep. 30, 2025
Fair Value Disclosures [Abstract]  
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis The following tables summarize, by level within the fair value hierarchy, our assets and liabilities that were accounted for at fair value on a recurring basis as of September 30, 2025 and 2024. As required under authoritative accounting literature, assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement.
Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)
Netting and
Cash
Collateral
September 30, 2025
 (In thousands)
Assets:
Financial instruments$— $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 $— $— $6,485 
Quoted
Prices in
Active
Markets
(Level 1)
Significant
Other
Observable
Inputs
(Level 2)(1)
Significant
Other
Unobservable
Inputs
(Level 3)
Netting and
Cash
Collateral
September 30, 2024
 (In thousands)
Assets:
Financial instruments$— $96,288 $— $— $96,288 
Debt and equity securities
Registered investment companies28,311 — — — 28,311 
Bond mutual funds40,341 — — — 40,341 
Bonds (2)
— 39,142 — — 39,142 
Money market funds— 2,800 — — 2,800 
Total debt and equity securities68,652 41,942 — — 110,594 
Total assets$68,652 $138,230 $— $— $206,882 
Liabilities:
Financial instruments$— $7,637 $— $— $7,637 
 
(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 which 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 Value and Fair Value of Our Long-term Debt The following table presents the carrying value and fair value of our long-term debt, excluding finances leases, debt issuance costs and original issue premium or discount, as of September 30, 2025:
 September 30, 2025
 (In thousands)
Carrying Amount$8,935,000 
Fair Value$8,272,978 
v3.25.3
Nature of Business (Details)
customer in Millions
Sep. 30, 2025
regulated_distribution_division
facility
customer
mi
Product Information [Line Items]  
Number of customers serviced | customer 3.4
Number of regulated distribution divisions | regulated_distribution_division 6
Number of underground storage facilities | facility 5
State of Louisiana | Pipeline and Storage  
Product Information [Line Items]  
Length of pipeline | mi 21
v3.25.3
Summary of Significant Accounting Policies - Narrative (Details)
1 Months Ended 12 Months Ended
Nov. 30, 2023
USD ($)
Dec. 31, 2023
USD ($)
Sep. 30, 2025
USD ($)
plan
mi
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Alternative Revenue Program [Line Items]          
Number of asset management plans under management | plan     2    
Composite depreciation rate for regulated property, plant and equipment     2.80% 2.90% 3.00%
Impairment of long-lived assets     $ 0 $ 0 $ 0
Derivative, cash collateral     0 $ 0  
Self-insured retention     $ 1,000,000    
Pipeline and Storage          
Alternative Revenue Program [Line Items]          
Regulatory mechanism threshold (in percent)     75.00%    
Rate case revenue benchmark $ 69,400,000 $ 106,900,000      
Pipeline and Storage | State of Louisiana          
Alternative Revenue Program [Line Items]          
Length of pipeline | mi     21    
v3.25.3
Summary of Significant Accounting Policies - Schedule of Capitalization (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Accounting Policies [Abstract]      
Debt $ 21,104 $ 14,655 $ 15,808
Equity 75,425 58,234 64,019
AFUDC $ 96,529 $ 72,889 $ 79,827
v3.25.3
Regulation (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Regulatory Assets [Line Items]    
Regulatory assets $ 608,729 $ 579,390
Regulatory Liabilities [Line Items]    
Regulatory liabilities 1,269,648 1,227,882
Regulatory excess deferred taxes    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 190,274 257,001
Regulatory cost of removal obligation    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 641,019 607,032
Deferred gas costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 6,879 9,142
APT annual adjustment mechanism    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 99,393 73,119
Pension and postretirement benefit costs    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 291,351 247,250
Other    
Regulatory Liabilities [Line Items]    
Regulatory liabilities 40,732 34,338
Pension and postretirement benefit costs    
Regulatory Assets [Line Items]    
Regulatory assets 262 11,243
Infrastructure mechanisms    
Regulatory Assets [Line Items]    
Regulatory assets 314,047 246,734
Winter Storm Uri incremental costs    
Regulatory Assets [Line Items]    
Regulatory assets 5,841 10,373
Deferred gas costs    
Regulatory Assets [Line Items]    
Regulatory assets 140,626 159,762
Regulatory excess deferred taxes    
Regulatory Assets [Line Items]    
Regulatory assets 49,793 51,380
Recoverable loss on reacquired debt    
Regulatory Assets [Line Items]    
Regulatory assets 2,903 3,070
Deferred pipeline record collection costs    
Regulatory Assets [Line Items]    
Regulatory assets 39,035 41,742
System Safety and Integrity Riders    
Regulatory Assets [Line Items]    
Regulatory assets 43,625 38,632
Other    
Regulatory Assets [Line Items]    
Regulatory assets $ 12,597 $ 16,454
v3.25.3
Segment Information - Narrative (Details)
12 Months Ended
Sep. 30, 2025
state
segment
Segment Reporting [Abstract]  
Number of reportable segments | segment 2
Number of states with service areas | state 8
v3.25.3
Segment Information - Schedule of Income Statements and Capital Expenditures By Segment (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Segment Reporting Information [Line Items]      
Operating revenues $ 4,702,755 $ 4,165,187 $ 4,275,357
Operation and maintenance expense 874,910 808,435 743,658
Depreciation and amortization expense 734,745 669,972 604,327
Interest charges 171,678 190,632 137,281
Income tax expense 279,280 192,881 113,779
Other segment items 2,231,330 1,948,355 2,399,957
Net income 1,198,754 1,042,895 885,862
Capital expenditures 3,561,399 2,937,124 2,805,973
Distribution      
Segment Reporting Information [Line Items]      
Operating revenues 4,422,355 3,912,134 4,096,661
Operation and maintenance expense 644,924 589,864 543,078
Depreciation and amortization expense 543,840 491,982 434,721
Interest charges 99,226 117,086 77,185
Income tax expense 150,961 96,041 60,032
Other segment items 2,239,665 1,948,755 2,404,277
Net income 746,781 671,413 580,397
Capital expenditures 2,662,703 2,249,280 1,927,125
Pipeline and Storage      
Segment Reporting Information [Line Items]      
Operating revenues 280,400 253,053 178,696
Operation and maintenance expense 229,986 218,571 200,580
Depreciation and amortization expense 190,905 177,990 169,606
Interest charges 72,452 73,546 60,096
Income tax expense 128,319 96,840 53,747
Other segment items (8,335) (400) (4,320)
Net income 451,973 371,482 305,465
Capital expenditures 898,696 687,844 878,848
Intersegment Eliminations      
Segment Reporting Information [Line Items]      
Operating revenues (787,942) (687,983) (609,507)
Intersegment Eliminations | Distribution      
Segment Reporting Information [Line Items]      
Operating revenues (3,042) (3,007) (3,029)
Intersegment Eliminations | Pipeline and Storage      
Segment Reporting Information [Line Items]      
Operating revenues (784,900) (684,976) (606,478)
Operating Segments      
Segment Reporting Information [Line Items]      
Operating revenues 5,490,697 4,853,170 4,884,864
Operating Segments | Distribution      
Segment Reporting Information [Line Items]      
Operating revenues 4,425,397 3,915,141 4,099,690
Operating Segments | Pipeline and Storage      
Segment Reporting Information [Line Items]      
Operating revenues $ 1,065,300 $ 938,029 $ 785,174
v3.25.3
Segment Information - Schedule of Revenue from External Customers by Products and Services (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues $ 4,702,755 $ 4,165,187 $ 4,275,357
Distribution      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 4,422,355 3,912,134 4,096,661
Distribution | Gas sales revenues      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 4,246,018 3,753,132 3,965,371
Distribution | Transportation revenues      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 149,853 132,608 119,371
Distribution | Other gas revenues      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 26,484 26,394 11,919
Distribution | Residential | Gas sales revenues      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 2,916,245 2,583,681 2,638,689
Distribution | Commercial | Gas sales revenues      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 1,154,591 1,016,675 1,112,236
Distribution | Industrial | Gas sales revenues      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 122,576 100,596 151,970
Distribution | Public authority and other | Gas sales revenues      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues 52,606 52,180 62,476
Pipeline and Storage      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Total operating revenues $ 280,400 $ 253,053 $ 178,696
v3.25.3
Segment Information - Schedule of Balance Sheet Information by Segment (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Segment Reporting Information [Line Items]    
Property, plant and equipment, net $ 25,292,990 $ 22,204,367
Total assets 28,249,522 25,194,465
Operating Segments    
Segment Reporting Information [Line Items]    
Property, plant and equipment, net 25,292,990 22,204,367
Total assets 34,193,451 30,510,435
Operating Segments | Distribution    
Segment Reporting Information [Line Items]    
Property, plant and equipment, net 18,765,128 16,372,659
Total assets 27,296,805 24,328,877
Operating Segments | Pipeline and Storage    
Segment Reporting Information [Line Items]    
Property, plant and equipment, net 6,527,862 5,831,708
Total assets 6,896,646 6,181,558
Intersegment Eliminations    
Segment Reporting Information [Line Items]    
Total assets $ (5,943,929) $ (5,315,970)
v3.25.3
Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Basic Earnings Per Share      
Net income $ 1,198,754 $ 1,042,895 $ 885,862
Less: Income allocated to participating securities 487 553 542
Net income available to common shareholders $ 1,198,267 $ 1,042,342 $ 885,320
Basic weighted average shares outstanding (in shares) 158,943 152,508 145,121
Net income per share — Basic (USD per share) $ 7.54 $ 6.83 $ 6.10
Diluted Earnings Per Share      
Net income available to common shareholders $ 1,198,267 $ 1,042,342 $ 885,320
Effect of dilutive shares 0 0 0
Net income available to common shareholders $ 1,198,267 $ 1,042,342 $ 885,320
Basic weighted average shares outstanding (in shares) 158,943 152,508 145,121
Dilutive shares (in shares) 1,630 158 45
Diluted weighted average shares outstanding (in shares) 160,573 152,666 145,166
Net income per share — Diluted (USD per share) $ 7.46 $ 6.83 $ 6.10
v3.25.3
Revenue and Accounts Receivable - Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Disaggregation of Revenue [Line Items]      
Total operating revenues $ 4,702,755 $ 4,165,187 $ 4,275,357
Mississippi recovery of uncollectible accounts   (4,192)  
Distribution      
Disaggregation of Revenue [Line Items]      
Total operating revenues 4,422,355 3,912,134 4,096,661
Pipeline and Storage      
Disaggregation of Revenue [Line Items]      
Total operating revenues 280,400 253,053 178,696
Operating Segments      
Disaggregation of Revenue [Line Items]      
Total operating revenues 5,490,697 4,853,170 4,884,864
Operating Segments | Distribution      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 4,361,803 3,847,167 4,051,778
Alternative revenue program revenues 49,215 52,401 43,139
Other revenues 14,379 15,573 4,773
Total operating revenues 4,425,397 3,915,141 4,099,690
Operating Segments | Distribution | Gas sales revenues      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 4,196,804 3,700,731 3,920,314
Operating Segments | Distribution | Gas sales revenues | Residential      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 2,877,456 2,542,438 2,606,658
Operating Segments | Distribution | Gas sales revenues | Commercial      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 1,145,710 1,006,593 1,100,773
Operating Segments | Distribution | Gas sales revenues | Industrial      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 122,284 100,363 151,538
Operating Segments | Distribution | Gas sales revenues | Public authority and other      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 51,354 51,337 61,345
Operating Segments | Distribution | Transportation revenues      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 151,876 134,600 121,420
Operating Segments | Distribution | Miscellaneous revenues      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 13,123 11,836 10,044
Operating Segments | Pipeline and Storage      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 1,131,764 998,687 824,148
Alternative revenue program revenues (66,464) (60,658) (38,974)
Other revenues 0 0 0
Total operating revenues 1,065,300 938,029 785,174
Operating Segments | Pipeline and Storage | Gas sales revenues      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 0 0 0
Operating Segments | Pipeline and Storage | Gas sales revenues | Residential      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 0 0 0
Operating Segments | Pipeline and Storage | Gas sales revenues | Commercial      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 0 0 0
Operating Segments | Pipeline and Storage | Gas sales revenues | Industrial      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 0 0 0
Operating Segments | Pipeline and Storage | Gas sales revenues | Public authority and other      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 0 0 0
Operating Segments | Pipeline and Storage | Transportation revenues      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers 1,119,015 982,795 811,968
Operating Segments | Pipeline and Storage | Miscellaneous revenues      
Disaggregation of Revenue [Line Items]      
Revenues from contracts with customers $ 12,749 $ 15,892 $ 12,180
v3.25.3
Revenue and Accounts Receivable - Narrative (Details)
$ in Thousands
3 Months Ended 12 Months Ended 42 Months Ended
Dec. 31, 2023
USD ($)
Sep. 30, 2025
USD ($)
state
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Sep. 30, 2025
USD ($)
state
Nov. 30, 2023
Disaggregation of Revenue [Line Items]            
Number of states excluded due to gas cost recovery mechanisms | state   6     6  
Percent of customers excluded due to gas cost recovery mechanisms   89.00%        
Reduction to bad debt expense   $ (30,778) $ (24,843) $ (22,353)    
Recovery of uncollectible accounts, not yet been written off     $ 4,192      
Mississippi Public Service Commission            
Disaggregation of Revenue [Line Items]            
Recovery of uncollectible accounts, term 2 years         1 year
Reduction to bad debt expense $ 13,900          
Recovery of uncollectible accounts, previously written off but not yet recovered through rates         $ 9,700  
Recovery of uncollectible accounts, not yet been written off   $ 4,200        
Pipeline and Storage            
Disaggregation of Revenue [Line Items]            
Regulatory mechanism threshold (in percent)   75.00%        
v3.25.3
Revenue and Accounts Receivable - Rollforward of Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]      
Beginning balance $ 37,056 $ 40,840 $ 49,993
Current period provisions 30,778 24,843 22,353
Write-offs charged against allowance (24,631) (26,165) (33,595)
Recoveries of amounts previously written off 2,056 1,730 2,089
Mississippi recovery of uncollectible accounts   (4,192)  
Ending balance $ 45,259 $ 37,056 $ 40,840
v3.25.3
Leases - Weighted Averages (Details)
Sep. 30, 2025
Sep. 30, 2024
Weighted average remaining lease term (years)    
Finance leases 15 years 8 months 12 days 16 years 8 months 12 days
Operating leases 8 years 9 months 18 days 9 years 10 months 24 days
Weighted average discount rate    
Finance leases 4.00% 4.00%
Operating leases 4.50% 4.10%
v3.25.3
Leases - Lease Cost (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Lessee, Finance Lease, Description [Abstract]      
Finance lease cost $ 4,467 $ 4,523 $ 4,499
Operating lease cost 56,695 48,421 44,090
Total lease cost $ 61,162 $ 52,944 $ 48,589
v3.25.3
Leases - ROU Assets and Lease Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Assets    
Finance leases $ 42,064 $ 44,748
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Public Utilities, Property, Plant and Equipment, Net Public Utilities, Property, Plant and Equipment, Net
Operating leases $ 293,934 $ 249,556
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Deferred charges and other assets Deferred charges and other assets
Total right-of-use assets $ 335,998 $ 294,304
Current    
Finance leases $ 1,775 $ 1,651
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Current maturities of long-term debt Current maturities of long-term debt
Operating leases $ 45,010 $ 34,340
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Other current liabilities Other current liabilities
Noncurrent    
Finance leases $ 45,459 $ 47,239
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Long-term debt Long-term debt
Operating leases $ 262,549 $ 224,498
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Deferred credits and other liabilities Deferred credits and other liabilities
Total $ 354,793 $ 307,728
v3.25.3
Leases - Narrative (Details)
$ in Millions
Dec. 31, 2025
USD ($)
service_center
Sep. 30, 2025
USD ($)
service_center
Subsequent Event [Line Items]    
Number of service center leases, not yet commenced | service_center   3
Lessee, future payments, not yet commenced | $   $ 116.5
Subsequent Event    
Subsequent Event [Line Items]    
Number of service center leases, not yet commenced | service_center 1  
Lessee, future payments, not yet commenced | $ $ 33.1  
v3.25.3
Leases - Other Pertinent Information (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Leases [Abstract]      
Operating cash flows used for operating leases $ 52,528 $ 47,069 $ 45,463
Right-of-use assets obtained in exchange for lease obligations      
Finance leases 0 0 0
Operating leases $ 89,598 $ 65,672 $ 29,976
v3.25.3
Leases - Maturities of Lease Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Leases [Abstract]    
2026 $ 60,048  
2027 55,881  
2028 50,775  
2029 44,304  
2030 38,240  
Thereafter 189,621  
Total lease payments 438,869  
Less: Imputed interest 84,076  
Total 354,793 $ 307,728
Short-term lease liabilities 46,785  
Long-term lease liabilities 308,008  
Finance Leases    
2026 3,502  
2027 3,568  
2028 3,635  
2029 3,703  
2030 3,782  
Thereafter 44,877  
Total lease payments 63,067  
Less: Imputed interest 15,833  
Total 47,234 48,890
Short-term lease liabilities 1,775 1,651
Long-term lease liabilities 45,459 47,239
Operating Leases    
2026 56,546  
2027 52,313  
2028 47,140  
2029 40,601  
2030 34,458  
Thereafter 144,744  
Total lease payments 375,802  
Less: Imputed interest 68,243  
Total 307,559  
Short-term lease liabilities 45,010 34,340
Long-term lease liabilities $ 262,549 $ 224,498
v3.25.3
Debt - Schedule of Long-term Debt Instruments (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Debt Instrument [Line Items]    
Long term debt $ 8,935,000  
Finance lease obligations 47,234 $ 48,890
Total long-term debt 8,982,234 7,833,890
Less:    
Net original issue premium on unsecured senior notes and debentures (1,332) (9,071)
Debt issuance cost 64,622 57,664
Current maturities 11,775 1,651
Long-term debt, noncurrent $ 8,907,169 7,783,646
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 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 0
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 0
Medium term Series A notes, 1995-1, 6.67%, due December 2025    
Debt Instrument [Line Items]    
Interest rate 6.67%  
Long term debt $ 10,000 10,000
Unsecured 6.75% Debentures, due July 2028    
Debt Instrument [Line Items]    
Interest rate 6.75%  
Long term debt $ 150,000 $ 150,000
v3.25.3
Debt - Schedule of Maturities of Long-term Debt (Details)
$ in Thousands
Sep. 30, 2025
USD ($)
Debt Disclosure [Abstract]  
2026 $ 10,000
2027 500,000
2028 150,000
2029 500,000
2030 0
Thereafter 7,775,000
Total long-term debt $ 8,935,000
v3.25.3
Debt - Narrative (Details)
1 Months Ended 12 Months Ended
Jun. 26, 2025
USD ($)
Apr. 01, 2025
USD ($)
Mar. 31, 2025
USD ($)
Oct. 01, 2024
USD ($)
Jun. 21, 2024
USD ($)
Mar. 28, 2024
USD ($)
Mar. 27, 2024
USD ($)
Oct. 10, 2023
USD ($)
Sep. 30, 2025
USD ($)
credit_facility
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Sep. 30, 2025
USD ($)
credit_facility
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Oct. 01, 2025
USD ($)
Debt Instrument [Line Items]                              
Proceeds from issuance long term debt                       $ 1,143,447,000 $ 1,240,204,000 $ 797,258,000  
Offering received                       $ 122,874,000 231,138,000 $ 171,145,000  
Ratio of total debt to total capitalization maximum                       70.00%      
Ratio of indebtedness to net capital                 0.41     0.41      
Minimum                              
Debt Instrument [Line Items]                              
Outstanding indebtedness                 $ 15,000,000     $ 15,000,000      
Maximum                              
Debt Instrument [Line Items]                              
Outstanding indebtedness                 100,000,000     $ 100,000,000      
Senior Notes                              
Debt Instrument [Line Items]                              
Offering received                 122,900,000 $ 231,100,000 $ 171,100,000        
Unsecured 5.45% Senior Notes, Due January 2056 | Senior Notes                              
Debt Instrument [Line Items]                              
Proceeds from issuance long term debt                 $ 589,800,000            
Unsecured 5.45% Senior Notes, Due January 2056 | Senior Notes | Subsequent Event                              
Debt Instrument [Line Items]                              
Debt face amount                             $ 600,000,000
Interest rate                             5.45%
Effective rate                             4.85%
Unsecured 5.20% Senior Notes, due August 2035                              
Debt Instrument [Line Items]                              
Interest rate                 5.20%     5.20%      
Unsecured 5.20% Senior Notes, due August 2035 | Senior Notes                              
Debt Instrument [Line Items]                              
Debt face amount $ 500,000,000                            
Interest rate 5.20%                            
Effective rate 5.35%                            
Proceeds from issuance long term debt $ 493,700,000                            
Unsecured 5.00% Senior Notes, due December 2054                              
Debt Instrument [Line Items]                              
Interest rate                 5.00%     5.00%      
Unsecured 5.00% Senior Notes, due December 2054 | Senior Notes                              
Debt Instrument [Line Items]                              
Debt face amount       $ 650,000,000                      
Interest rate       5.00%                      
Effective rate       3.90%                      
Proceeds from issuance long term debt       $ 639,400,000                      
Unsecured 5.90% Senior Notes, due November 2033                              
Debt Instrument [Line Items]                              
Interest rate                 5.90%     5.90%      
Unsecured 5.90% Senior Notes, due November 2033 | Senior Notes                              
Debt Instrument [Line Items]                              
Debt face amount         $ 325,000,000     $ 400,000,000              
Interest rate         5.90%     5.90%              
Effective rate         5.17%     4.35%              
Proceeds from issuance long term debt         $ 339,000,000                    
Unsecured 6.20% Senior Notes, due November 2053                              
Debt Instrument [Line Items]                              
Interest rate                 6.20%     6.20%      
Unsecured 6.20% Senior Notes, due November 2053 | Senior Notes                              
Debt Instrument [Line Items]                              
Debt face amount               $ 500,000,000              
Interest rate               6.20%              
Effective rate               5.56%              
Unsecured Senior Notes Due 2033 and Unsecured Senior Notes Due 2053 | Senior Notes                              
Debt Instrument [Line Items]                              
Proceeds from issuance of debt               $ 889,400,000              
Five Year Unsecured Revolving Credit Agreement, Maturing On March 28, 2029 | Minimum | Base Rate                              
Debt Instrument [Line Items]                              
Basis spread percent                       0.00%      
Five Year Unsecured Revolving Credit Agreement, Maturing On March 28, 2029 | Minimum | Secured Overnight Financing Rate (SOFR)                              
Debt Instrument [Line Items]                              
Basis spread percent                       0.75%      
Five Year Unsecured Revolving Credit Agreement, Maturing On March 28, 2029 | Maximum | Base Rate                              
Debt Instrument [Line Items]                              
Basis spread percent                       0.25%      
Five Year Unsecured Revolving Credit Agreement, Maturing On March 28, 2029 | Maximum | Secured Overnight Financing Rate (SOFR)                              
Debt Instrument [Line Items]                              
Basis spread percent                       1.25%      
Five Year Unsecured Revolving Credit Agreement, Maturing On March 28, 2029 | Commercial Paper                              
Debt Instrument [Line Items]                              
Maximum borrowing capacity                 $ 1,500,000,000     $ 1,500,000,000      
Credit facility, accordion feature                 250,000,000     250,000,000      
Loan increase potential                 1,750,000,000     1,750,000,000      
Five Year Unsecured Revolving Credit Agreement, Maturing On March 28, 2029 | Revolving Credit Facility                              
Debt Instrument [Line Items]                              
Maximum borrowing capacity                 $ 3,100,000,000     $ 3,100,000,000      
Number of credit facilities | credit_facility                 4     4      
Five Year Unsecured Revolving Credit Agreement                              
Debt Instrument [Line Items]                              
Commercial paper                 $ 0     $ 0      
Five Year Unsecured Revolving Credit Agreement | Commercial Paper                              
Debt Instrument [Line Items]                              
Maximum borrowing capacity             $ 1,500,000,000                
Debt term             5 years                
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility                              
Debt Instrument [Line Items]                              
Maximum borrowing capacity           $ 1,500,000,000                  
Debt term           3 years                  
Credit facility, accordion feature           $ 250,000,000                  
Loan increase potential           $ 1,750,000,000                  
Line of credit borrowings outstanding                 0 0   $ 0 0    
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Base Rate                              
Debt Instrument [Line Items]                              
Basis spread percent                       0.00%      
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Secured Overnight Financing Rate (SOFR)                              
Debt Instrument [Line Items]                              
Basis spread percent                       0.75%      
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Base Rate                              
Debt Instrument [Line Items]                              
Basis spread percent                       0.25%      
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Secured Overnight Financing Rate (SOFR)                              
Debt Instrument [Line Items]                              
Basis spread percent                       1.25%      
$900 Million Revolving Credit Facility | Revolving Credit Facility                              
Debt Instrument [Line Items]                              
Line of credit borrowings outstanding                 0 0   $ 0 0    
$50 Million Bank Loan Agreement | Line of Credit                              
Debt Instrument [Line Items]                              
Maximum borrowing capacity   $ 50,000,000                          
Debt term   364 days                          
Line of credit borrowings outstanding                 0 $ 0   0 $ 0    
$50 Million Revolving Credit Facility | Revolving Credit Facility                              
Debt Instrument [Line Items]                              
Maximum borrowing capacity     $ 50,000,000                        
Debt term     364 days                        
Line of credit borrowings outstanding                 0     0      
Remaining borrowing capacity                 $ 44,400,000     $ 44,400,000      
v3.25.3
Shareholders' Equity - Narrative (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Nov. 14, 2025
Dec. 03, 2024
Class of Stock [Line Items]          
Forward sales equity agreement, settlement in cash $ 1,558,522        
Net proceeds from equity offering $ 698,462 $ 749,987 $ 806,949    
Shelf Registration Statement          
Class of Stock [Line Items]          
Debt and equity securities, authorized for issuance         $ 8,000,000
Shelf Registration Statement | Subsequent Event          
Class of Stock [Line Items]          
Debt and equity securities, authorized for issuance value remaining       $ 5,200,000  
At-The-Market          
Class of Stock [Line Items]          
Value of shares authorized for issuance         $ 1,700,000
Forward sales equity agreement, shares (in shares) 5,967,768        
Forward sales equity agreement, settlement in cash $ 871,500        
Shares issued (in shares) 5,931,289        
Net proceeds from equity offering $ 698,500        
Value of shares available for issuance $ 828,500        
v3.25.3
Shareholders' Equity - Schedule of Forward Sales Executed (Details)
$ / shares in Units, $ in Thousands
12 Months Ended
Sep. 30, 2025
USD ($)
$ / shares
shares
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares Available (in shares) | shares 11,326,599
Net Proceeds Available | $ $ 1,558,522
Forward Price (USD per share) | $ / shares $ 137.60
December 31, 2025  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares Available (in shares) | shares 1,160,351
Net Proceeds Available | $ $ 148,610
Forward Price (USD per share) | $ / shares $ 128.07
March 31, 2026  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares Available (in shares) | shares 3,627,033
Net Proceeds Available | $ $ 465,210
Forward Price (USD per share) | $ / shares $ 128.26
June 30, 2026  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares Available (in shares) | shares 669,043
Net Proceeds Available | $ $ 89,572
Forward Price (USD per share) | $ / shares $ 133.88
December 31, 2026  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares Available (in shares) | shares 3,392,352
Net Proceeds Available | $ $ 475,294
Forward Price (USD per share) | $ / shares $ 140.11
March 31, 2027  
Forward Contract Indexed to Issuer's Equity [Line Items]  
Shares Available (in shares) | shares 2,477,820
Net Proceeds Available | $ $ 379,836
Forward Price (USD per share) | $ / shares $ 153.29
v3.25.3
Shareholders' Equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Shareholders' equity, beginning balance $ 12,157,669 $ 10,870,064 $ 9,419,091
Other comprehensive income (loss) before reclassifications 24,204 (42,848)  
Amounts reclassified from accumulated other comprehensive income (14,904) (9,965)  
Total other comprehensive income (loss) 9,300 (52,813) 149,416
Shareholders' equity, ending balance 13,558,890 12,157,669 10,870,064
Available- for-Sale Securities      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Shareholders' equity, beginning balance 213 (369)  
Other comprehensive income (loss) before reclassifications (4) 582  
Amounts reclassified from accumulated other comprehensive income 0 0  
Total other comprehensive income (loss) (4) 582  
Shareholders' equity, ending balance 209 213 (369)
Interest Rate Agreement Cash Flow Hedges      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Shareholders' equity, beginning balance 465,502 518,897  
Other comprehensive income (loss) before reclassifications 24,208 (43,430)  
Amounts reclassified from accumulated other comprehensive income (14,904) (9,965)  
Total other comprehensive income (loss) 9,304 (53,395)  
Shareholders' equity, ending balance 474,806 465,502 518,897
Accumulated Other Comprehensive Income (Loss)      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Shareholders' equity, beginning balance 465,715 518,528 369,112
Total other comprehensive income (loss) 9,300 (52,813) 149,416
Shareholders' equity, ending balance $ 475,015 $ 465,715 $ 518,528
v3.25.3
Securitization - Narrative (Details) - USD ($)
1 Months Ended 12 Months Ended
Jun. 30, 2023
Mar. 31, 2023
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Variable Interest Entity [Line Items]          
Proceeds from issuance of securitized long-term debt by AEK     $ 0 $ 0 $ 95,000,000
Long-term debt, fair value     8,272,978,000    
State of Texas | Extraordinary Gas Cost | Winter Storm Uri          
Variable Interest Entity [Line Items]          
Regulatory asset, authorized   $ 3,500,000,000      
Regulatory asset, proceeds from customer rate relief bonds   $ 2,020,000,000.00      
State of Texas | Extraordinary Gas Cost | Winter Storm Uri | Minimum          
Variable Interest Entity [Line Items]          
Regulatory asset, maturity period   12 years      
State of Texas | Extraordinary Gas Cost | Winter Storm Uri | Maximum          
Variable Interest Entity [Line Items]          
Regulatory asset, maturity period   18 years      
Variable Interest Entity, Primary Beneficiary          
Variable Interest Entity [Line Items]          
Long-term debt     $ 77,003,000    
Variable Interest Entity, Primary Beneficiary | Securitized Utility Tariff Property          
Variable Interest Entity [Line Items]          
Proceeds from sale of intangible assets $ 92,300,000        
Initial consolidation, gain (loss) $ 0        
Intangible asset, useful life 10 years        
Intangible assets, amortization period     4 years 25 days    
Series 2023-A Securitized Utility Tariff Bonds Due March 2033 | Senior Notes | Variable Interest Entity, Primary Beneficiary          
Variable Interest Entity [Line Items]          
Debt face amount $ 95,000,000        
Debt instrument, interest rate 5.155%        
Debt instrument, term 10 years        
Proceeds from issuance of securitized long-term debt by AEK $ 93,700,000        
Long-term debt     $ 77,000,000.0 85,100,000  
Long-term debt, fair value     $ 78,800,000 $ 87,800,000  
v3.25.3
Securitization - Condensed Consolidated Balance Sheet (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents $ 1,116 $ 1,516
Other current assets 301,627 288,068
Securitized intangible asset, net 75,127 82,844
Accrued interest 122,459 106,116
Current maturities of securitized long-term debt 8,767 8,207
Securitized long-term debt 68,236 76,871
Variable Interest Entity, Primary Beneficiary    
Variable Interest Entity [Line Items]    
Restricted cash and cash equivalents 1,116 1,516
Other current assets 1 3
Securitized intangible asset, net 75,127 82,844
Accrued interest 331 365
Current maturities of securitized long-term debt 8,767 8,207
Securitized long-term debt $ 68,236 $ 76,871
v3.25.3
Securitization - Consolidated Statement of Comprehensive Income (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Variable Interest Entity [Line Items]      
Operating revenues $ 4,702,755 $ 4,165,187 $ 4,275,357
Operation and maintenance expense (902,942) (819,137) (764,906)
Amortization expense (734,745) (669,972) (604,327)
Interest expense, net (171,678) (190,632) (137,281)
Income before income taxes 1,478,034 1,235,776 999,641
Variable Interest Entity, Primary Beneficiary      
Variable Interest Entity [Line Items]      
Operating revenues 12,408 13,660 2,743
Operation and maintenance expense (559) (427) 0
Amortization expense (7,717) (8,715) (1,398)
Interest expense, net (4,132) (4,518) (1,345)
Income before income taxes $ 0 $ 0 $ 0
v3.25.3
Securitization - Maturities of the Securitized Long-term Debt and Amortization Expense to the Securitized Intangible Assets (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Maturities of Securitized Long-Term Debt    
2026 $ 10,000  
2027 500,000  
2028 150,000  
2029 500,000  
2030 0  
Thereafter 7,775,000  
Amortization Expense of Securitized Intangible Asset    
Total 75,127 $ 82,844
Variable Interest Entity, Primary Beneficiary    
Maturities of Securitized Long-Term Debt    
2026 8,767  
2027 9,086  
2028 9,561  
2029 10,060  
2030 10,585  
Thereafter 28,944  
Total 77,003  
Amortization Expense of Securitized Intangible Asset    
2026 8,555  
2027 9,001  
2028 9,471  
2029 9,966  
2030 10,486  
Thereafter 27,648  
Total $ 75,127 $ 82,844
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Narrative (Details)
$ in Thousands
12 Months Ended
Jan. 01, 2026
Sep. 30, 2025
USD ($)
plan
shares
Sep. 30, 2024
USD ($)
shares
Sep. 30, 2023
USD ($)
Defined Benefit Plan Disclosure [Line Items]        
Recovery period   15 years    
Supplemental Executive Benefit Plan        
Defined Benefit Plan Disclosure [Line Items]        
Number of nonqualified supplemental plans offered | plan   3    
Retirement Savings Plan        
Defined Benefit Plan Disclosure [Line Items]        
New employee contribution percentage   5.00%    
Years of service   1 year    
Maximum of eligible compensation   65.00%    
Employer matching, percent of employee salary   5.00%    
Automatic increase feature   1.00%    
Deferral rate   10.00%    
Percent of employee contribution   100.00%    
Fixed annual contribution percent   4.00%    
Contribution plan cost   $ 34,300 $ 26,800 $ 23,900
Percent of common stock outstanding   1.10% 1.20%  
Retirement Savings Plan | Forecast        
Defined Benefit Plan Disclosure [Line Items]        
Employer matching, percent of employee salary 6.00%      
Employee Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Vesting period   3 years    
Employer contributions   $ 0 $ 5,000  
Accounts receivable   $ 5,100 $ 700  
Employee Pension Plan | Minimum        
Defined Benefit Plan Disclosure [Line Items]        
Medium-term horizon   3 years    
Employee Pension Plan | Maximum        
Defined Benefit Plan Disclosure [Line Items]        
Medium-term horizon   5 years    
Employee Pension Plan | Company stock        
Defined Benefit Plan Disclosure [Line Items]        
Shares held by plan (in shares) | shares   506,700 716,700  
Percent of plan assets   14.00% 16.70%  
Dividend income   $ 1,900 $ 2,300  
Employee Pension Plan | Retirement Savings Plan        
Defined Benefit Plan Disclosure [Line Items]        
Employer matching, percent of employee salary   10.00%    
Supplemental Executive Retirement Plans        
Defined Benefit Plan Disclosure [Line Items]        
Employer contributions   $ 0 0  
Settlement charge   0 (1,529) (1,030)
Lump sum settlement   0 0  
Assets held-in-trust   $ 30,100 31,100  
Supplemental Executive Retirement Plans | Supplemental Executive Benefit Plan        
Defined Benefit Plan Disclosure [Line Items]        
Percent of covered compensation   75.00%    
Supplemental Executive Retirement Plans | 1998 Supplemental Executive Retirement Plan, Defined Benefit        
Defined Benefit Plan Disclosure [Line Items]        
Percent of covered compensation   60.00%    
Supplemental Executive Retirement Plans | 2009 Supplemental Executive Retirement Plan, Defined Benefit        
Defined Benefit Plan Disclosure [Line Items]        
Vesting period   3 years    
Contribution percent   10.00%    
Contribution percent for members   25.00%    
Attainment age   55 years    
Supplemental Executive Retirement Plans | Executive Officer        
Defined Benefit Plan Disclosure [Line Items]        
Settlement charge     (1,500) (1,000)
Lump sum settlement     9,600 $ 5,600
Postretirement Plan        
Defined Benefit Plan Disclosure [Line Items]        
Employer contributions   $ 0 $ 0  
Postretirement Plan | Minimum        
Defined Benefit Plan Disclosure [Line Items]        
Expected contribution amount   13,000    
Postretirement Plan | Maximum        
Defined Benefit Plan Disclosure [Line Items]        
Expected contribution amount   $ 18,000    
Postretirement Plan | Diversified investment funds        
Defined Benefit Plan Disclosure [Line Items]        
Percent of plan assets   98.60% 97.80%  
Maximum investment percent   75.00%    
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Schedule of Net Periodic Benefit Cost Not yet Recognized (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Unrecognized prior service credit | Supplemental Executive Retirement Plans    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets $ 0 $ 0
Unrecognized actuarial (gain) loss | Supplemental Executive Retirement Plans    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets 17,661 16,136
Total unrecognized in net periodic pension cost | Supplemental Executive Retirement Plans    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets 17,661 16,136
Unrecognized prior service credit    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets (9,984) (24,897)
Unrecognized prior service credit | Employee Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets 0 0
Unrecognized prior service credit | Postretirement Plan    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets (9,984) (24,897)
Unrecognized actuarial (gain) loss    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets (278,380) (222,353)
Unrecognized actuarial (gain) loss | Employee Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets (179,351) (126,989)
Unrecognized actuarial (gain) loss | Postretirement Plan    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets (116,690) (111,500)
Total unrecognized in net periodic pension cost | Employee Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets (179,351) (126,989)
Total unrecognized in net periodic pension cost | Postretirement Plan    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets (126,674) (136,397)
Total unrecognized in net periodic pension cost | Pension and postretirement benefit costs    
Defined Benefit Plan Disclosure [Line Items]    
Net regulatory assets $ (288,364) $ (247,250)
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Asset Allocation (Details)
Sep. 30, 2025
Sep. 30, 2024
Employee Pension Plan | Domestic equities    
Defined Benefit Plan Disclosure [Line Items]    
Asset allocation 43.60% 42.80%
Employee Pension Plan | Domestic equities | Minimum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 35.00%  
Employee Pension Plan | Domestic equities | Maximum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 55.00%  
Employee Pension Plan | International equities    
Defined Benefit Plan Disclosure [Line Items]    
Asset allocation 15.50% 15.80%
Employee Pension Plan | International equities | Minimum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 10.00%  
Employee Pension Plan | International equities | Maximum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 20.00%  
Employee Pension Plan | Fixed income    
Defined Benefit Plan Disclosure [Line Items]    
Asset allocation 24.30% 22.30%
Employee Pension Plan | Fixed income | Minimum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 5.00%  
Employee Pension Plan | Fixed income | Maximum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 45.00%  
Employee Pension Plan | Company stock    
Defined Benefit Plan Disclosure [Line Items]    
Asset allocation 14.00% 16.70%
Employee Pension Plan | Company stock | Minimum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 0.00%  
Employee Pension Plan | Company stock | Maximum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 15.00%  
Employee Pension Plan | Other assets    
Defined Benefit Plan Disclosure [Line Items]    
Asset allocation 2.60% 2.40%
Employee Pension Plan | Other assets | Minimum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 0.00%  
Employee Pension Plan | Other assets | Maximum    
Defined Benefit Plan Disclosure [Line Items]    
Targeted Allocation Range 20.00%  
Postretirement Plan | Diversified investment funds    
Defined Benefit Plan Disclosure [Line Items]    
Asset allocation 98.60% 97.80%
Postretirement Plan | Cash and cash equivalents    
Defined Benefit Plan Disclosure [Line Items]    
Asset allocation 1.40% 2.20%
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Schedule of Assumptions Used (Details)
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Oct. 01, 2026
Sep. 30, 2026
Employee Pension Plan          
Defined Benefit Plan Disclosure [Line Items]          
Discount rate pension asset 5.45% 5.02%      
Discount rate pension cost 5.02% 6.10% 5.66%    
Rate of compensation increase pension asset 3.50% 3.50%      
Rate of compensation increase pension cost 3.50% 3.50% 3.50%    
Expected return on plan assets pension asset 6.50% 6.50%      
Expected return on plan assets pension cost 6.50% 6.25% 6.25%    
Interest crediting rate increase pension asset 4.69% 4.69%      
Interest crediting rate increase pension cost 4.69% 4.69% 4.69%    
Employee Pension Plan | Forecast          
Defined Benefit Plan Disclosure [Line Items]          
Interest crediting rate increase pension asset       4.69% 4.73%
Supplemental Executive Retirement Plans          
Defined Benefit Plan Disclosure [Line Items]          
Discount rate pension liability 5.14% 4.92%      
Discount rate pension cost 4.92% 5.85% 5.50%    
Rate of compensation increase pension liability 3.50% 3.50%      
Rate of compensation increase pension cost 3.50% 3.50% 3.50%    
Interest crediting rate increase pension liability 4.69% 4.69%      
Interest crediting rate increase pension cost 4.69% 4.69% 4.69%    
Supplemental Executive Retirement Plans | Forecast          
Defined Benefit Plan Disclosure [Line Items]          
Interest crediting rate increase pension liability       4.69% 4.73%
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Plans’ Accumulated Benefit Obligation, Projected Benefit Obligation and Funded Status (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Reconciliation:      
Net amount recognized $ 226,409 $ 155,611  
Employee Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Accumulated benefit obligation 428,845 448,353  
Change in projected benefit obligation:      
Benefit obligation at beginning of year 470,902 431,560  
Service cost 10,047 9,546 $ 10,805
Interest cost 23,164 25,731 24,924
Actuarial (gain) loss (18,133) 44,205  
Benefits paid (35,556) (40,140)  
Benefit obligation at end of year 450,424 470,902 431,560
Change in plan assets:      
Fair value of plan assets at beginning of year 595,212 502,412  
Actual return on plan assets 64,847 127,940  
Employer contribution 0 5,000  
Benefits paid (35,556) (40,140)  
Fair value of plan assets at end of year 624,503 595,212 $ 502,412
Reconciliation:      
Funded status 174,079 124,310  
Unrecognized prior service cost 0 0  
Unrecognized net loss 0 0  
Net amount recognized $ 174,079 $ 124,310  
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Schedule of Net Benefit Costs (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Employee Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Other non-operating income Other non-operating income Other non-operating income
Components of net periodic postretirement cost:      
Service cost $ 10,047 $ 9,546 $ 10,805
Interest cost 23,164 25,731 24,924
Expected return on assets (30,618) (28,808) (29,113)
Amortization of prior service credit 0 0 (121)
Recognized actuarial gain 0 (67) 0
Net periodic pension cost $ 2,593 $ 6,402 $ 6,495
Supplemental Executive Retirement Plans      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Other non-operating income Other non-operating income Other non-operating income
Components of net periodic postretirement cost:      
Service cost $ 1,302 $ 55 $ 845
Interest cost 3,488 4,024 4,227
Recognized actuarial gain 1,022 501 691
Settlements 0 1,529 1,030
Net periodic pension cost $ 5,812 $ 6,109 $ 6,793
Postretirement Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Other non-operating income Other non-operating income Other non-operating income
Components of net periodic postretirement cost:      
Service cost $ 8,132 $ 6,028 $ 6,183
Interest cost 13,463 14,034 13,911
Expected return on assets (15,325) (12,511) (11,215)
Amortization of prior service credit (13,040) (13,040) (13,142)
Recognized actuarial gain (9,716) (10,872) (7,452)
Net periodic pension cost $ (16,486) $ (16,361) $ (11,715)
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Schedule of Employee Pension Plans Investments at Fair Value (Details) - Employee Pension Plan - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Derivatives, Fair Value [Line Items]      
Total investments $ 624,503 $ 595,212 $ 502,412
Fair Value, Recurring      
Derivatives, Fair Value [Line Items]      
Total investments 619,429 594,491  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3      
Derivatives, Fair Value [Line Items]      
Total investments 499,028 459,723  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3 | Common stocks      
Derivatives, Fair Value [Line Items]      
Total investments 284,573 289,301  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3 | Money market funds      
Derivatives, Fair Value [Line Items]      
Total investments 16,293 14,542  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3 | Registered investment companies      
Derivatives, Fair Value [Line Items]      
Total investments 123,022 90,086  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3 | Mortgage-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 26,101 24,383  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3 | U.S. treasuries      
Derivatives, Fair Value [Line Items]      
Total investments 15,047 9,425  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3 | Corporate bonds      
Derivatives, Fair Value [Line Items]      
Total investments 32,517 31,986  
Fair Value, Recurring | Fair Value, Inputs, Level 1, 2 and 3 | Asset-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 1,475    
Fair Value, Recurring | Level 1      
Derivatives, Fair Value [Line Items]      
Total investments 422,616 388,785  
Fair Value, Recurring | Level 1 | Common stocks      
Derivatives, Fair Value [Line Items]      
Total investments 284,573 289,301  
Fair Value, Recurring | Level 1 | Money market funds      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 1 | Registered investment companies      
Derivatives, Fair Value [Line Items]      
Total investments 123,022 90,086  
Fair Value, Recurring | Level 1 | Mortgage-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 1 | U.S. treasuries      
Derivatives, Fair Value [Line Items]      
Total investments 15,021 9,398  
Fair Value, Recurring | Level 1 | Corporate bonds      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 1 | Asset-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 0    
Fair Value, Recurring | Level 2      
Derivatives, Fair Value [Line Items]      
Total investments 76,412 70,938  
Fair Value, Recurring | Level 2 | Common stocks      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 2 | Money market funds      
Derivatives, Fair Value [Line Items]      
Total investments 16,293 14,542  
Fair Value, Recurring | Level 2 | Registered investment companies      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 2 | Mortgage-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 26,101 24,383  
Fair Value, Recurring | Level 2 | U.S. treasuries      
Derivatives, Fair Value [Line Items]      
Total investments 26 27  
Fair Value, Recurring | Level 2 | Corporate bonds      
Derivatives, Fair Value [Line Items]      
Total investments 32,517 31,986  
Fair Value, Recurring | Level 2 | Asset-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 1,475    
Fair Value, Recurring | Level 3      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 3 | Common stocks      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 3 | Money market funds      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 3 | Registered investment companies      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 3 | Mortgage-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 3 | U.S. treasuries      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 3 | Corporate bonds      
Derivatives, Fair Value [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Level 3 | Asset-backed securities      
Derivatives, Fair Value [Line Items]      
Total investments 0    
Fair Value, Recurring | Fair Value Measured at Net Asset Value Per Share | Common/collective trusts      
Derivatives, Fair Value [Line Items]      
Total investments 95,558 111,103  
Fair Value, Recurring | Fair Value Measured at Net Asset Value Per Share | Limited partnerships      
Derivatives, Fair Value [Line Items]      
Total investments $ 24,843 $ 23,665  
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Supplemental Plans’ Accumulated Benefit Obligation, Projected Benefit Obligation and Funded Status (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Reconciliation:      
Net amount recognized $ 226,409 $ 155,611  
Supplemental Executive Retirement Plans      
Defined Benefit Plan Disclosure [Line Items]      
Accumulated benefit obligation 73,570 71,003  
Change in projected benefit obligation:      
Benefit obligation at beginning of year 71,944 75,898  
Service cost 1,302 55 $ 845
Interest cost 3,488 4,024 4,227
Actuarial loss 2,547 5,853  
Benefits paid (4,761) (4,285)  
Settlements 0 (9,601)  
Benefit obligation at end of year 74,520 71,944 75,898
Change in plan assets:      
Fair value of plan assets at beginning of year 0 0  
Employer contribution 0 0  
Benefits paid 0 0  
Settlements 0 0  
Fair value of plan assets at end of year 0 0 $ 0
Reconciliation:      
Funded status (74,520) (71,944)  
Unrecognized prior service cost 0 0  
Unrecognized net loss 0 0  
Net amount recognized $ (74,520) $ (71,944)  
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Schedule of Expected Benefit Payments Defined Benefit Plan (Details)
$ in Thousands
Sep. 30, 2025
USD ($)
Pension Plan  
Defined Benefit Plan Disclosure [Line Items]  
2026 $ 40,122
2027 39,190
2028 38,729
2029 38,798
2030 38,777
2031-2035 178,831
Supplemental Plans  
Defined Benefit Plan Disclosure [Line Items]  
2026 6,277
2027 9,627
2028 28,392
2029 3,783
2030 3,615
2031-2035 $ 31,031
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Actuarial Assumptions For Net Periodic Pension Cost (Details) - Postretirement Plan
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]      
Discount rate pension asset 5.47% 5.01%  
Discount rate postretirement cost 5.01% 6.06% 5.61%
Expected return on plan assets pension asset 5.14% 5.14%  
Expected return on plan assets postretirement cost 5.14% 4.94% 4.94%
Initial trend rate pension asset 7.00% 6.75%  
Initial trend rate postretirement cost 6.75% 6.50% 6.25%
Ultimate trend rate pension asset 5.00% 5.00%  
Ultimate trend rate postretirement cost 5.00% 5.00% 4.75%
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Postretirement Plans’ Accumulated Benefit Obligation, Projected Benefit Obligation and Funded Status (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Reconciliation:      
Net amount recognized $ 226,409 $ 155,611  
Postretirement Plan      
Change in projected benefit obligation:      
Benefit obligation at beginning of year 269,391 234,004  
Service cost 8,132 6,028 $ 6,183
Interest cost 13,463 14,034 13,911
Plan participants’ contributions 1,993 2,102  
Actuarial (gain) loss (8,733) 31,135  
Benefits paid (19,065) (17,912)  
Plan amendments 1,873 0  
Benefit obligation at end of year 267,054 269,391 234,004
Change in plan assets:      
Fair value of plan assets at beginning of year 300,692 255,800  
Actual return on plan assets 21,500 47,857  
Employer contributions 0 0  
Benefits paid (2,808) (2,965)  
Fair value of plan assets at end of year 319,384 300,692 $ 255,800
Reconciliation:      
Funded status 52,330 31,301  
Unrecognized prior service cost 0 0  
Unrecognized prior service cost 0 0  
Unrecognized net loss 0 0  
Net amount recognized $ 52,330 $ 31,301  
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Schedule of Postretirement Benefit Plans Investments at Fair Value (Details) - Postretirement Plan - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments $ 319,384 $ 300,692 $ 255,800
Fair Value, Recurring      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 319,384 300,692  
Fair Value, Recurring | Level 1      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 314,956 294,059  
Fair Value, Recurring | Level 2      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 4,428 6,633  
Fair Value, Recurring | Level 3      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Money market funds      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 4,428 6,633  
Fair Value, Recurring | Money market funds | Level 1      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Money market funds | Level 2      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 4,428 6,633  
Fair Value, Recurring | Money market funds | Level 3      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Registered investment companies      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 314,956 294,059  
Fair Value, Recurring | Registered investment companies | Level 1      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 314,956 294,059  
Fair Value, Recurring | Registered investment companies | Level 2      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments 0 0  
Fair Value, Recurring | Registered investment companies | Level 3      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Total investments $ 0 $ 0  
v3.25.3
Retirement and Postretirement Employee Benefit Plans - Schedule of Expected Benefit Payments Post Retirement Benefit Plan (Details) - Postretirement Plan
$ in Thousands
Sep. 30, 2025
USD ($)
Company Payments  
2026 $ 18,898
2027 18,859
2028 18,783
2029 19,011
2030 19,364
2031-2035 104,216
Retiree Payments  
2026 2,425
2027 2,320
2028 2,186
2029 2,112
2030 2,083
2031-2035 10,770
Subsidy Payments  
2026 0
2027 0
2028 0
2029 0
2030 0
2031-2035 0
Total Postretirement Benefits  
2026 21,323
2027 21,179
2028 20,969
2029 21,123
2030 21,447
2031-2035 $ 114,986
v3.25.3
Stock and Other Compensation Plans - Narrative (Details) - USD ($)
shares in Millions
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]      
Stock-based compensation cost $ 33,200,000 $ 25,400,000 $ 23,700,000
Capitalized stock-based compensation cost $ 20,500,000 14,700,000 13,500,000
Maximum shares authorized (in shares) 13.2    
Shares available for future issuance (in shares) 2.2    
Service period 3 years    
Unrecognized compensation cost $ 21,600,000    
Cost recognition period 1 year 3 months 18 days    
Fair value of restricted stock vested $ 24,000,000.0 $ 21,600,000 $ 22,800,000
Minimum initial investment 1,250    
Minimum cash payments 25    
Maximum annual cash payments $ 100,000    
v3.25.3
Stock and Other Compensation Plans - Schedule of Activity (Details) - $ / shares
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Number of Restricted Units      
Nonvested at beginning of year (in shares) 397,929 389,957 381,295
Granted (in shares) 229,828 212,207 241,436
Vested (in shares) (215,806) (201,834) (220,929)
Forfeited (in shares) (3,815) (2,401) (11,845)
Nonvested at end of year (in shares) 408,136 397,929 389,957
Weighted Average Grant-Date Fair Value      
Nonvested at beginning of year (USD per share) $ 113.78 $ 109.10 $ 105.69
Granted (USD per share) 135.68 117.11 109.78
Vested (USD per share) 111.75 108.56 104.05
Forfeited (USD per share) 127.58 115.44 107.47
Nonvested at end of year (USD per share) $ 127.74 $ 113.78 $ 109.10
v3.25.3
Details of Selected Financial Statement Captions - Accounts Receivables (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Condensed Balance Sheet Statements, Captions [Line Items]    
Total accounts receivable $ 420,768 $ 402,938
Less: allowance for uncollectible accounts (45,259) (37,056)
Net accounts receivable 375,509 365,882
Billed and Unbilled Receivables | Billed accounts receivable    
Condensed Balance Sheet Statements, Captions [Line Items]    
Total accounts receivable 213,651 220,869
Billed and Unbilled Receivables | Unbilled revenue    
Condensed Balance Sheet Statements, Captions [Line Items]    
Total accounts receivable 140,651 123,550
Insurance receivable    
Condensed Balance Sheet Statements, Captions [Line Items]    
Total accounts receivable 22,940 51,715
Other accounts receivable    
Condensed Balance Sheet Statements, Captions [Line Items]    
Total accounts receivable $ 43,526 $ 6,804
v3.25.3
Details of Selected Financial Statement Captions - Other Current Assets (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]    
Deferred gas costs $ 140,626 $ 159,762
Winter Storm Uri incremental costs 5,841 3,949
Prepaid expenses 80,495 74,780
Taxes receivable 8,948 14,332
Materials and supplies 20,076 16,961
Assets from risk management activities 5,303 2,091
Regulatory assets (See Note 3) 33,311 12,297
Other 7,027 3,896
Total $ 301,627 $ 288,068
v3.25.3
Details of Selected Financial Statement Captions - Property, Plant and Equipment (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]    
Storage plant $ 790,621 $ 708,617
Transmission plant 6,308,557 5,713,831
Distribution plant 19,788,099 17,304,207
General plant 1,102,931 1,019,018
Intangible plant 38,612 38,612
Property, plant and equipment 28,028,820 24,784,285
Construction in progress 1,235,316 1,063,798
Total property, plant and equipment and construction in progress 29,264,136 25,848,083
Less: accumulated depreciation and amortization (3,971,146) (3,643,716)
Net property, plant and equipment 25,292,990 22,204,367
Plant acquisition adjustments $ (21,100) $ (22,900)
v3.25.3
Details of Selected Financial Statement Captions - Deferred Charges and Other Assets (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]    
Marketable securities $ 114,938 $ 110,594
Regulatory assets (See Note 3) 428,951 396,958
Operating lease right of use assets (See Note 7) 293,934 249,556
Winter Storm Uri incremental costs 0 6,424
Assets from risk management activities 4,594 94,197
Pension and postretirement assets 226,409 155,611
Other 28,627 30,343
Total $ 1,097,453 $ 1,043,683
v3.25.3
Details of Selected Financial Statement Captions - Accounts Payable and Accrued Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]    
Trade accounts payable $ 380,999 $ 341,948
Accrued gas payable 37,073 19,125
Accrued liabilities 88,444 84,324
Total $ 506,516 $ 445,397
v3.25.3
Details of Selected Financial Statement Captions - Other Current Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]    
Customer credit balances and deposits $ 56,185 $ 62,085
Accrued employee costs 69,062 64,141
Deferred gas costs 6,879 9,142
Operating lease liabilities (See Note 7) 45,010 34,340
Accrued interest 122,459 106,116
Liabilities from risk management activities 6,339 7,324
Taxes payable 237,965 215,857
Pension and postretirement liabilities 6,122 4,622
Regulatory cost of removal obligation 108,558 99,217
APT annual adjustment mechanism 68,094 35,924
Regulatory excess deferred taxes (See Note 15) 72,792 79,686
Other 36,092 32,166
Total $ 835,557 $ 750,620
v3.25.3
Details of Selected Financial Statement Captions - Deferred Credits and Other Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Balance Sheet Related Disclosures [Abstract]    
Pension and postretirement liabilities $ 68,398 $ 67,322
Operating lease liabilities (See Note 7) 262,549 224,498
Customer advances for construction 9,573 7,973
Other regulatory liabilities (See Note 3) 332,017 279,979
Asset retirement obligation 7,428 7,942
Liabilities from risk management activities 146 313
APT annual adjustment mechanism 31,299 37,195
Unrecognized tax benefits (See Note 15) 50,210 46,174
Other 22,702 20,536
Total $ 784,322 $ 691,932
v3.25.3
Details of Selected Financial Statement Captions - Other Non-Operating Income (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]      
Equity component of AFUDC $ 75,425 $ 58,234 $ 64,019
Performance-based rate program 8,485 8,389 7,093
Pension and other postretirement non-service credit 14,372 10,820 8,955
Interest income 29,944 22,887 7,207
Community support spending (21,114) (20,016) (12,027)
Unrealized gains on equity securities 174 3,562 1,406
Miscellaneous (17,545) (12,830) (6,878)
Total $ 89,741 $ 71,046 $ 69,775
v3.25.3
Details of Selected Financial Statement Captions - Supplemental Cash Flow Information (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Cash Paid (Received) During The Period For:      
Interest $ 349,222 $ 308,872 $ 249,066
Income taxes:      
Federal (5,000) 8,200 (4,500)
Total income taxes 4,452 15,349 14,968
Non-Cash Transactions:      
Capital expenditures included in current liabilities 327,814 299,908 186,912
Interest paid, net of amount capitalized 155,300 163,500 117,900
State of Texas      
Income taxes:      
State 7,095 5,372 17,200
State of Louisiana      
Income taxes:      
State 2,357 1,739 2,232
Other states      
Income taxes:      
State $ 0 $ 38 $ 36
v3.25.3
Commitments and Contingencies (Details)
$ in Millions
12 Months Ended
Jan. 27, 2024
fatality
incident
Sep. 30, 2025
USD ($)
$ / Mcf
MMcf
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Dec. 02, 2024
fatality
Long Term Purchase Commitment [Line Items]          
Purchases under contract | $   $ 153.4 $ 105.7 $ 182.0  
Supply Commitment          
Long Term Purchase Commitment [Line Items]          
Contract term   1 year      
Purchase commitment volume   21,000.0      
Supply Commitment | Weighted Average          
Long Term Purchase Commitment [Line Items]          
Fixed price contracts (USD per Mcf) | $ / Mcf   2.70      
Supply Commitment | Short-term Contract with Customer          
Long Term Purchase Commitment [Line Items]          
Contract term   1 year      
Purchase commitment volume   73,400      
Supply Commitment | Long-term Contract with Customer Within Two To Three Years          
Long Term Purchase Commitment [Line Items]          
Purchase commitment volume   114,900      
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Minimum          
Long Term Purchase Commitment [Line Items]          
Contract term   2 years      
Supply Commitment | Long-term Contract with Customer Within Two To Three Years | Maximum          
Long Term Purchase Commitment [Line Items]          
Contract term   3 years      
National Transportation Safety Board          
Long Term Purchase Commitment [Line Items]          
Number of fatalities under investigation | fatality 1       1
Jackson, Mississippi | National Transportation Safety Board          
Long Term Purchase Commitment [Line Items]          
Number of incidents investigated that occurred during period | incident 2        
v3.25.3
Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Effective Income Tax Rate Reconciliation, Amount      
U.S federal statutory tax rate $ 310,387 $ 259,513 $ 209,925
State and local income taxes, net of federal income tax effect 24,254 27,367 19,853
Changes in valuation allowances 0 1,106 0
Changes in unrecognized tax benefits 2,004 926 5,302
Nontaxable or nondeductible items 741 2,464 1,000
Amortization of excess deferred taxes (60,727) (100,270) (123,953)
Other, net 2,621 1,775 1,652
Income tax expense $ 279,280 $ 192,881 $ 113,779
Effective Income Tax Rate Reconciliation, Percent      
U.S federal statutory tax rate 21.00% 21.00% 21.00%
State and local income taxes, net of federal income tax effect 1.60% 2.20% 2.00%
Changes in valuation allowances 0.00% 0.10% 0.00%
Changes in unrecognized tax benefits 0.10% 0.10% 0.50%
Nontaxable or nondeductible items 0.10% 0.20% 0.10%
Amortization of excess deferred taxes (4.10%) (8.10%) (12.40%)
Other, net 0.20% 0.10% 0.20%
Income tax expense 18.90% 15.60% 11.40%
v3.25.3
Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Deferred tax assets:    
Employee benefit plans $ 34,202 $ 41,184
Net operating loss carryforwards 473,642 484,816
Charitable and other credit carryforwards 14,200 12,301
Regulatory excess deferred tax 31,387 46,330
Lease asset 72,973 63,747
Other 31,145 34,934
Total deferred tax assets 657,549 683,312
Valuation allowance (1,365) (1,457)
Net deferred tax assets 656,184 681,855
Deferred tax liabilities:    
Difference in net book value and net tax value of assets (3,200,535) (2,914,854)
Gas cost adjustments (43,819) (49,443)
Winter Storm Uri regulatory asset (17,993) (20,846)
Lease liability (66,831) (57,177)
Rate deferral adjustment (64,640) (50,571)
Interest rate agreements (135,640) (134,536)
Other (45,073) (47,770)
Total deferred tax liabilities (3,574,531) (3,275,197)
Net deferred tax liabilities $ (2,918,347) $ (2,593,342)
v3.25.3
Income Taxes - Narrative (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Income Tax Contingency [Line Items]      
Charitable contribution carryforwards $ 11,800    
Remeasured federal effects 600    
Unrecognized tax benefits, period increase 60,300 $ 57,800  
Unrecognized tax benefits, deferred tax liabilities 10,100 11,600  
Interest and penalties 100 100 $ 3,400
Payment of interest and penalties accrued 15,100 15,100 $ 15,100
Regulatory liabilities 1,269,648 1,227,882  
Regulatory excess net deferred tax liability 140,500    
Deferred tax liabilities, net 2,918,347 2,593,342  
Regulatory excess deferred taxes      
Income Tax Contingency [Line Items]      
Regulatory liabilities 190,274 257,001  
Regulatory excess deferred taxes to be returned tranche one      
Income Tax Contingency [Line Items]      
Deferred tax liabilities, net $ 91,800    
Regulatory excess deferred taxes to be returned tranche one | Minimum      
Income Tax Contingency [Line Items]      
Return basis, term 36 months    
Regulatory excess deferred taxes to be returned tranche one | Maximum      
Income Tax Contingency [Line Items]      
Return basis, term 60 months    
Regulatory excess deferred taxes to be returned tranche two      
Income Tax Contingency [Line Items]      
Regulatory liabilities $ 47,700    
Regulatory excess deferred taxes to be returned tranche two | Minimum      
Income Tax Contingency [Line Items]      
Return basis, term 15 years    
Regulatory excess deferred taxes to be returned tranche two | Maximum      
Income Tax Contingency [Line Items]      
Return basis, term 69 years    
Regulatory excess deferred taxes to be returned tranche three      
Income Tax Contingency [Line Items]      
Deferred tax liabilities, net $ 1,000    
Other current liabilities | Regulatory excess deferred taxes      
Income Tax Contingency [Line Items]      
Regulatory liabilities 72,800 $ 79,700  
Domestic Tax Jurisdiction      
Income Tax Contingency [Line Items]      
Federal net operating loss carryforwards 435,300    
State and Local Jurisdiction      
Income Tax Contingency [Line Items]      
Federal net operating loss carryforwards 38,300    
Federal effects 10,100    
Federal alternative minimum tax credit carryforwards $ 2,400    
v3.25.3
Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Reconciliation of Unrecognized Tax Benefits [Roll Forward]      
Unrecognized tax benefits - beginning balance $ 57,797 $ 58,638 $ 52,683
Decrease resulting from prior period tax positions (1,759) (2,867) (631)
Decrease resulting from a lapse in statute of limitations (5,699) (6,188) 0
Increase resulting from current period tax positions 9,993 8,214 6,586
Unrecognized tax benefits - ending balance 60,332 57,797 58,638
Less: deferred federal and state income tax benefits (12,670) (12,137) (12,314)
Total unrecognized tax benefits that, if recognized, would impact the effective income tax rate as of the end of the year 47,662 $ 45,660 $ 46,324
Anticipated regulatory offset $ 43,300    
v3.25.3
Financial Instruments - Narrative (Details)
12 Months Ended
Sep. 30, 2025
USD ($)
$ / Mcf
MMcf
Sep. 30, 2024
USD ($)
Sep. 30, 2023
USD ($)
Derivative [Line Items]      
Purchase commitment volume | MMcf 32,566    
Contract netting $ 0 $ 0  
Cash collateral 0 0  
Net (gain) loss on settled interest rate agreements (20,500,000) $ (12,800,000) $ (2,700,000)
Net realized gains in AOCI $ 474,800,000    
Not Designated As Hedges | Gas Purchases | Commodity contracts      
Derivative [Line Items]      
Purchase commitment volume | MMcf 24,000.0    
Not Designated As Hedges | Gas Purchases | Commodity contracts | Minimum      
Derivative [Line Items]      
Hedging percent 25.00%    
Not Designated As Hedges | Gas Purchases | Commodity contracts | Maximum      
Derivative [Line Items]      
Hedging percent 50.00%    
Not Designated As Hedges | Gas Purchases | Commodity contracts | Weighted Average      
Derivative [Line Items]      
Derivative flow rate (USD per Mcf) | $ / Mcf 3.83    
v3.25.3
Financial Instruments - Schedule of Financial Instruments on the Balance Sheet (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, assets $ 9,897 $ 96,288
Gross/net financial instruments, liabilities (6,485) (7,637)
Designated As Hedges:    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, assets   91,981
Gross/net financial instruments, liabilities   0
Designated As Hedges: | Deferred charges and other assets | Interest rate contracts    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, assets   91,981
Designated As Hedges: | Deferred credits and other liabilities | Interest rate contracts    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, liabilities   0
Not Designated As Hedges:    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, assets 9,897 4,307
Gross/net financial instruments, liabilities (6,485) (7,637)
Not Designated As Hedges: | Other current assets | Commodity contracts    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, assets 5,303 2,091
Not Designated As Hedges: | Other current liabilities | Commodity contracts    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, liabilities (6,339) (7,324)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, assets 4,594 2,216
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts    
Derivatives, Fair Value [Line Items]    
Gross/net financial instruments, liabilities $ (146) $ (313)
v3.25.3
Financial Instruments - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2023
Increase (decrease) in fair value:      
Interest rate agreements $ 24,208 $ (43,430)  
Recognition of gains in earnings due to settlements:      
Interest rate agreements (14,904) (9,965)  
Total other comprehensive income (loss) from hedging, net of tax $ 9,304 $ (53,395) $ 149,290
v3.25.3
Financial Instruments - Schedule of Expected Recognition in Earnings of the Deferred Net Gains Recorded in AOCI (Details) - Interest rate contracts
$ in Thousands
12 Months Ended
Sep. 30, 2025
USD ($)
Expected Earnings [Line Items]  
2026 $ 19,093
2027 19,093
2028 19,093
2029 19,093
2030 19,093
Thereafter 379,341
Total $ 474,806
v3.25.3
Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)
$ in Thousands
Sep. 30, 2025
Sep. 30, 2024
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments, net assets $ 9,897 $ 96,288
Total debt and equity securities 114,938 110,594
Total assets 124,835 206,882
Financial instruments, net liability 6,485 7,637
Registered investment companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 26,463 28,311
Bond mutual funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 42,106 40,341
Bonds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Bonds 42,754 39,142
Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 3,615 2,800
Quoted Prices in Active Markets (Level 1)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments 0 0
Total debt and equity securities 68,569 68,652
Total assets 68,569 68,652
Financial instruments 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 26,463 28,311
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 42,106 40,341
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 9,897 96,288
Total debt and equity securities 46,369 41,942
Total assets 56,266 138,230
Financial instruments 6,485 7,637
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 42,754 39,142
Significant Other Observable Inputs (Level 2) | Money market funds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities 3,615 2,800
Significant Other Unobservable Inputs (Level 3)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Financial instruments 0 0
Total debt and equity securities 0 0
Total assets 0 0
Financial instruments 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
v3.25.3
Fair Value Measurements - Narrative (Details) - USD ($)
Sep. 30, 2025
Sep. 30, 2024
Fair Value Disclosures [Abstract]    
Allowance for credit loss $ 0  
Amortized cost $ 42,500,000 $ 38,900,000
v3.25.3
Fair Value Measurements - Schedule of Carrying Value and Fair Value of Our Long-term Debt (Details)
$ in Thousands
Sep. 30, 2025
USD ($)
Fair Value Disclosures [Abstract]  
Carrying Amount $ 8,935,000
Fair Value $ 8,272,978