Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Revenues
Member electric sales	$ 346,802	$ 326,251	$ 921,476	$ 873,537
Non-member electric sales	25,354	29,039	85,825	84,215
Other	24,355	23,062	66,540	64,684
Total revenues	396,511	378,352	1,073,841	1,022,436
Operating expenses
Purchased power	100,547	99,312	259,322	246,905
Fuel	68,337	67,839	187,658	180,389
Production	46,756	51,699	157,405	159,697
Transmission	38,752	41,383	113,038	116,975
General and administrative	7,326	6,463	19,347	17,965
Depreciation, amortization, and depletion	43,332	45,314	131,094	126,090
Coal mining	12,330	10,174	30,090	25,845
Other	4,185	3,969	12,953	12,989
Operating expenses	321,565	326,153	910,907	886,855
Operating margins	74,946	52,199	162,934	135,581
Other income
Interest	1,177	1,094	3,397	3,227
Capital credits from cooperatives	1,323	1,105	5,720	5,800
Membership withdrawal			5,000
Other income	1,118	864	2,547	2,599
Total other income	3,618	3,063	16,664	11,626
Interest expense, net of amounts capitalized	37,289	37,041	109,937	108,385
Income tax expense (benefit)	(259)	350	(863)	700
Net margins including noncontrolling interest	41,534	17,871	70,524	38,122
Net income attributable to noncontrolling interest	(736)	(132)	(1,409)	(313)
Net margins attributable to the Association	$ 40,798	$ 17,739	$ 69,115	$ 37,809