Consolidated Statements of Revenues and Expenses - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating revenues:
Total operating revenues	$ 384,644	$ 376,656	$ 1,124,211	$ 1,092,195
Operating expenses:
Fuel	151,903	143,767	394,494	366,405
Production	95,971	93,657	299,134	293,930
Depreciation and amortization	56,936	56,143	170,565	167,983
Purchased power	15,381	14,345	46,030	44,222
Accretion	9,608	9,224	28,364	27,333
Total operating expenses	329,799	317,136	938,587	899,873
Operating margin	54,845	59,520	185,624	192,322
Other income:
Investment income	15,242	14,850	43,925	44,509
Other	1,765	627	5,383	1,908
Total other income	17,007	15,477	49,308	46,417
Interest charges:
Interest expense	92,492	93,809	273,987	280,621
Allowance for debt funds used during construction	(35,123)	(33,517)	(104,272)	(99,953)
Amortization of debt discount and expense	3,149	3,150	9,198	9,386
Net interest charges	60,518	63,442	178,913	190,054
Net margin	11,334	11,555	56,019	48,685
Members
Operating revenues:
Total operating revenues	384,529	376,508	1,123,741	1,091,975
Non-Members
Operating revenues:
Total operating revenues	$ 115	$ 148	$ 470	$ 220