STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating activities
Net income	$ 264,224	$ 222,850	$ 231,232
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	317,256	296,699	279,830
Deferred income tax provision	49,507	106,522	24,773
Share-based compensation expense	14,791	13,733	12,184
Provision for doubtful accounts	8,207	6,705	9,698
Proceeds from Securitization Bonds, Operating Activities	0	0	197,366
Changes in assets and liabilities:
Accounts receivable	(61,390)	(67,289)	196,272
Materials and supplies	(5,933)	(14,013)	(6,776)
Income tax receivable	(1,928)	(49,677)	(3,947)
Natural gas in storage	(15,267)	25,913	82,108
Asset removal costs	(52,268)	(58,952)	(62,023)
Accounts payable	(35,397)	(15,014)	(90,046)
Accrued taxes other than income	(40)	6,815	(9,559)
Customer deposits	(3,372)	(5,944)	4,333
Regulatory assets and liabilities, current, net	68,397	(90,829)	7,249
Regulatory assets and liabilities, noncurrent, net	36,660	19,354	38,869
Other current assets and liabilities, net	(708)	(17,091)	30,017
Other noncurrent assets and liabilities, net	(3,906)	(11,371)	(2,048)
Cash provided by operating activities	578,833	368,411	939,532
Investing activities
Capital expenditures	(707,226)	(703,165)	(666,634)
Payments for Other Investing Activities	(12,724)	(10,402)	(8,508)
Proceeds from Sale of Other Assets, Investing Activities	4,626	6,072	5,499
Cash used in investing activities	(715,324)	(707,495)	(669,643)
Financing activities
Borrowings (repayments) of short-term debt, net	(177,200)	826,100	(463,500)
Proceeds from issuance of long-term debt, net of premiums and discounts	250,000	253,467	299,583
Payments of Debt Issuance Costs	(432)	2,193	2,508
Repayments of Other Long-Term Debt	(15)	(773,013)	0
Repayment of securitized utility tariff bonds	(29,493)	(27,939)	(20,716)
Proceeds from Issuance of Common Stock	212,183	252,379	85,259
Dividends paid	(160,705)	(149,456)	(144,094)
Payment, Tax Withholding, Share-based Payment Arrangement	(2,657)	(1,111)	(2,653)
Cash used in financing activities	91,681	378,234	(248,629)
Change in cash and cash equivalents	(44,810)	39,150	21,260
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning Balance	78,537	39,387	18,127
Cash, cash equivalents, restricted cash and restricted cash equivalents at end of period	33,727	78,537	39,387
Interest Paid, Excluding Capitalized Interest	138,987	148,987	80,726
Income Tax Paid, State and Local, after Refund Received	540	366	769
Income Tax Paid, Oklahoma, after Refund Received	(1,523)	(4,546)	1,571
Income Tax Paid, Federal, after Refund Received	$ 10,113	$ (16,280)	$ 18,504