Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net margin	$ 42,099	$ 24,410
Adjustments to reconcile net margin to net cash provided by operating activities:
Depreciation and amortization, including nuclear fuel	131,940	92,645
Accretion cost	17,622	15,508
Amortization of deferred gains	(447)	(447)
Allowance for equity funds used during construction	(347)	(149)
Deferred outage costs	(11,856)	(21,198)
Loss on sale of investments	471	1,289
Regulatory deferral of costs associated with nuclear decommissioning	(8,125)	(8,519)
Other	(14,480)	(1,043)
Change in operating assets and liabilities:
Receivables	26,609	49,887
Inventories	7,683	(17,711)
Prepayments and other current assets	(30,569)	4,027
Accounts payable	(49,628)	(116,354)
Accrued interest	14,718	(13,109)
Accrued taxes	(33,733)	(36,722)
Other current liabilities	24,494	(26,841)
Rate management program billing credits applied	(35,646)	(9,494)
Other	17,336	(989)
Total adjustments	56,042	(89,220)
Net cash provided by (used in) operating activities	98,141	(64,810)
Cash flows from investing activities:
Property additions	(174,270)	(285,233)
Activity in nuclear decommissioning trust fund—Purchases	(140,865)	(2,500)
Activity in nuclear decommissioning trust fund—Proceeds	136,894	283
Decrease in restricted investments	0	74,031
Activity in long-term and short-term investments—Purchases	(82,283)	(63,505)
Activity in other long-term investments—Proceeds	80,672	68,226
Other	(3,512)	8,163
Net cash used in investing activities	(183,364)	(200,535)
Cash flows from financing activities:
Long-term debt proceeds	6,067	15,431
Long-term debt payments	(136,047)	(137,732)
Increase in short-term borrowings, net	54,894	157,375
Other	(2,813)	11,311
Net cash (used in) provided by financing activities	(77,899)	46,385
Net decrease in cash, cash equivalents and restricted cash	(163,122)	(218,960)
Cash, cash equivalents and restricted cash at beginning of period	490,592	625,781
Cash, cash equivalents and restricted cash at end of period	327,470	406,821
Cash paid for—
Interest (net of amounts capitalized)	80,063	61,915
Supplemental disclosure of non-cash investing and financing activities:
Change in asset retirement obligations	65,149	87,509
Accrued property additions at end of period	$ 41,104	$ 69,557