Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net margin	$ 40,147	$ 39,103
Adjustments to reconcile net margin to net cash provided by operating activities:
Depreciation and amortization, including nuclear fuel	203,299	199,649
Accretion cost	27,392	27,722
Amortization of deferred gains	(894)	(894)
Allowance for equity funds used during construction	(291)	(138)
Deferred outage costs	(23,107)	(16,581)
Loss (gain) on sale of investments	18,467	(10,284)
Regulatory deferral of costs associated with nuclear decommissioning	(33,956)	(7,626)
Other	642	(698)
Change in operating assets and liabilities:
Receivables	(123,344)	(31,535)
Inventories	(21,933)	13,759
Prepayments and other current assets	(20,532)	5,349
Accounts payable	17,584	(32,833)
Accrued interest	(16,253)	1,619
Accrued taxes	35,915	(8,147)
Other current liabilities	64,929	(8,928)
Member power bill prepayments	(12,478)	(19,182)
Rate management program collections, net	13,960	78,524
Total adjustments	129,400	189,776
Net cash provided by operating activities	169,547	228,879
Cash flows from investing activities:
Property additions	(526,406)	(603,062)
Activity in nuclear decommissioning trust fund—Purchases	(199,140)	(374,059)
Activity in nuclear decommissioning trust fund - Proceeds	195,557	370,145
Increase in restricted cash and investments	184,812	109,302
Activity in other long-term investments—Purchases	(134,310)	(227,706)
Activity in other long-term investments - Proceeds	102,982	129,594
Other	2,615	8,663
Net cash used in investing activities	(373,890)	(587,123)
Cash flows from financing activities:
Long-term debt proceeds	792,503	503,431
Long-term debt payments	(256,747)	(123,520)
(Decrease) increase in short-term borrowings, net	(334,689)	206,467
Other	14,493	11,511
Net cash provided by financing activities	215,560	597,889
Net increase in cash, cash equivalents and restricted cash	11,217	239,645
Cash, cash equivalents and restricted cash at beginning of period	581,150	405,511
Cash, cash equivalents and restricted cash at end of period	592,367	645,156
Cash paid for—
Interest (net of amounts capitalized)	112,365	96,832
Supplemental disclosure of non-cash investing and financing activities:
Change in asset retirement obligations	0	(399)
Accrued property additions at end of period	64,476	70,537
Bond purchase fund included in cash and cash equivalents at end of period	$ 30,975	$ 245,605