Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating revenues
Other	$ 51,399	$ 50,202	$ 89,781
Operating revenues	1,385,472	1,320,837	1,388,593
Operating expenses
Purchased power	328,921	343,509	339,830
Fuel	280,325	237,721	244,328
Production	209,586	212,917	207,993
Transmission	163,757	161,652	153,510
General and administrative	49,607	33,046	28,704
Depreciation, amortization and depletion	157,734	154,975	174,526
Coal mining	10,027	637	40,034
Other	19,090	14,987	15,971
Operating expenses	1,219,047	1,159,444	1,204,896
Operating margins	166,425	161,393	183,697
Other income
Interest	6,175	5,294	4,723
Capital credits from cooperatives	9,799	27,373	12,934
Membership withdrawal			5,000
Other	18,427	5,131	3,966
Total other income	34,401	37,798	26,623
Interest expense, net of amounts capitalized	151,470	153,704	147,608
Income tax benefit	(307)	(534)	(1,092)
Net margins including noncontrolling interest	49,663	46,021	63,804
Net income attributable to noncontrolling interest	(4,354)	(3,287)	(2,148)
Net margins attributable to the Association	45,309	42,734	61,656
Member electric sales
Operating revenues
Operating revenues	1,238,672	1,235,872	1,199,940
Non-member electric sales
Operating revenues
Operating revenues	$ 95,401	$ 34,763	$ 98,872