Condensed Statements of Revenues and Expenses (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating revenues:
Sales to Members	$ 286,653	$ 295,230
Sales to non-Members	19,261	23,994
Total operating revenues	305,914	319,224
Operating expenses:
Fuel	100,150	109,227
Production	94,720	98,499
Depreciation and amortization	37,083	44,544
Purchased power	12,667	12,116
Accretion	5,630	4,857
Deferral of Hawk Road and Smith Energy Facilities effect on net margin	(11,890)	(12,075)
Total operating expenses	238,360	257,168
Operating margin	67,554	62,056
Other income:
Investment income	7,277	8,255
Other	2,277	3,743
Total other income	9,554	11,998
Interest charges:
Interest expense	75,777	76,007
Allowance for debt funds used during construction	(24,854)	(20,419)
Amortization of debt discount and expense	4,161	4,946
Net interest charges	55,084	60,534
Net margin	$ 22,024	$ 13,520