Consolidated Statements of Revenues and Expenses - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating revenues:
Sales to Members	$ 354,144	$ 348,097
Sales to non-Members	26	64
Total operating revenues	354,170	348,161
Operating expenses:
Fuel	103,915	98,952
Production	101,088	103,471
Depreciation and amortization	55,863	53,486
Purchased power	14,976	13,143
Accretion	8,998	8,016
Total operating expenses	284,840	277,068
Operating margin	69,330	71,093
Other income:
Investment income	14,819	12,323
Other	640	2,301
Total other income	15,459	14,624
Interest charges:
Interest expense	93,285	88,517
Allowance for debt funds used during construction	(33,087)	(26,380)
Amortization of debt discount and expense	3,137	2,982
Net interest charges	63,335	65,119
Net margin	$ 21,454	$ 20,598