Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net margin	$ 21,980	$ 25,958
Adjustments to reconcile net margin to net cash provided by operating activities:
Depreciation and amortization, including nuclear fuel	92,211	99,638
Accretion cost	13,532	13,781
Amortization of deferred gains	(447)	(447)
Allowance for equity funds used during construction	(135)	(26)
Deferred outage costs	(22,228)	(13,231)
Loss (gain) on sale of investments	8,271	(9,134)
Regulatory deferral of costs associated with nuclear decommissioning	(14,694)	284
Other	974	(641)
Change in operating assets and liabilities:
Receivables	(8,620)	1,455
Inventories	(715)	8,567
Prepayments and other current assets	5,954	4,039
Accounts payable	(78,836)	(41,415)
Accrued interest	(18,662)	4,300
Accrued taxes	16,180	(22,542)
Other current liabilities	29,836	(6,273)
Member power bill prepayments	(7,988)	(18,779)
Rate management program collections	11,017	37,979
Total adjustments	25,650	57,555
Net cash provided by operating activities	47,630	83,513
Cash flows from investing activities:
Property additions	(280,364)	(324,181)
Activity in nuclear decommissioning trust fund—Purchases	(195,038)	(250,195)
Activity in nuclear decommissioning trust fund - Proceeds	192,858	248,147
Decrease in restricted cash and investments	123,232	54,280
Activity in other long-term investments—Purchases	(111,490)	(120,752)
Activity in other long-term investments - Proceeds	94,279	72,293
Other	(3,718)	144
Net cash used in investing activities	(180,241)	(320,264)
Cash flows from financing activities:
Long-term debt proceeds	102,185	238,578
Long-term debt payments	(115,168)	(61,828)
Increase in short-term borrowings, net	60,501	217,674
Other	10,496	(2,083)
Net cash provided by financing activities	58,014	392,341
Net (decrease) increase in cash, cash equivalents and restricted cash	(74,597)	155,590
Cash, cash equivalents and restricted cash at beginning of period	581,150	405,511
Cash, cash equivalents and restricted cash at end of period	506,553	561,101
Cash paid for—
Interest (net of amounts capitalized)	66,117	45,127
Supplemental disclosure of non-cash investing and financing activities:
Change in asset retirement obligations	0	(399)
Accrued property additions at end of period	$ 21,469	$ 76,364