Condensed Statements of Revenues and Expenses (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Operating revenues:
Sales to Members	$ 338,768	$ 349,906	$ 944,481	$ 947,130
Sales to non-Members	38,628	82,624	99,842	134,977
Total operating revenues	377,396	432,530	1,044,323	1,082,107
Operating expenses:
Fuel	167,416	188,983	410,585	422,789
Production	91,753	90,101	280,096	269,154
Depreciation and amortization	37,789	51,382	122,889	136,714
Purchased power	15,158	20,925	44,341	46,080
Accretion	4,884	4,562	14,599	13,687
Deferral of Hawk Road and Smith Energy Facilities effect on net margin	(655)	13,240	(15,214)	2,168
Total operating expenses	316,345	369,193	857,296	890,592
Operating margin	61,051	63,337	187,027	191,515
Other income:
Investment income	6,435	7,147	22,450	21,467
Gain on termination of Rocky Mountain transactions	14,719		14,719
Other	2,591	3,198	9,490	9,980
Total other income	23,745	10,345	46,659	31,447
Interest charges:
Interest expense	76,443	75,704	231,290	218,649
Allowance for debt funds used during construction	(21,151)	(17,835)	(61,588)	(50,816)
Amortization of debt discount and expense	5,761	5,405	15,843	15,893
Net interest charges	61,053	63,274	185,545	183,726
Net margin	$ 23,743	$ 10,408	$ 48,141	$ 39,236