Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net margins including noncontrolling interest	$ 49,663	$ 46,021	$ 63,804
Adjustments to reconcile net margins to net cash provided by operating activities:
Depreciation, amortization and depletion	157,734	154,975	174,526
Amortization of intangible asset	3,662	7,324	7,324
Amortization of NRECA Retirement Security Plan prepayment	5,372	5,372	5,372
Amortization of debt issuance costs	2,375	2,641	1,985
Impairment loss - Holcomb expansion	37,067		93,494
Impairment loss		0
Deferred Nucla impairment loss	(37,067)		(93,494)
Recognition of deferred membership withdrawal income			(5,000)
Deferred revenue		51,679	9,527
Recognition of deferred revenue	(6,153)		(15,000)
Capital credit allocations from cooperatives and income from coal mines over refund distributions	(1,276)	(18,090)	(4,417)
Proceeds from settlement of interest rate swaps			4,625
Changes in operating assets and liabilities:
Accounts receivable	2,383	(5,922)	4,924
Coal inventory	5,692	(8,080)	17,097
Materials and supplies	154	(3,576)	(1,691)
Accounts payable and accrued expenses	1,136	(10,434)	628
Accrued interest	(2,354)	(782)	(1,313)
Accrued property taxes	547	1,446	(448)
Other deferred credits - TEP transmission (settlement) refund			(15,521)
Other	14,328	(6,297)	(6,039)
Net cash provided by operating activities	233,263	216,277	240,383
Investing activities
Purchases of plant	(212,815)	(280,712)	(214,781)
Changes in deferred charges	9,347	(2,233)	1,112
Proceeds from other investments	65	67	911
Net cash used in investing activities	(203,403)	(282,878)	(212,758)
Financing activities
Changes in Member advances	(4,177)	(1,717)	(6,852)
Payments of long-term debt	(96,099)	(133,848)	(108,301)
Proceeds from issuance of long-term debt	34,910	150,090	60,000
Debt issuance costs	(13)	(10,697)	(1,450)
Increase in short-term borrowings, net	48,178	59,478	24,767
Retirement of patronage capital	(23,303)	(15,339)	(12,815)
Equity distribution to noncontrolling interest	(2,806)	(4,413)
Other	(372)	(328)	101
Net cash provided by (used in) financing activities	(43,682)	43,226	(44,550)
Net decrease in cash, cash equivalents and restricted cash and investments	(13,822)	(23,375)	(16,925)
Cash, cash equivalents and restricted cash and investments – beginning	127,590	150,965	167,890
Cash, cash equivalents and restricted cash and investments – ending	113,768	127,590	150,965
Supplemental cash flow information:
Cash paid for interest	161,460	161,809	159,112
Supplemental disclosure of noncash investing and financing activities:
Change in plant expenditures included in accounts payable	$ (96)	$ (44)	$ (3,242)