Statements Of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Assignable margins	$ 5,525,507	$ 5,573,262	$ 5,410,009
Adjustments to reconcile assignable margins to net cash provided by operating activities:
Depreciation	32,356,900	32,616,175	32,636,108
Amortization and depreciation cleared to operating expenses	5,882,580	5,472,557	5,457,480
Allowance for funds used during construction	(258,301)	(159,916)	(83,966)
Loss on disposal of assets	991,871	851,756	210,596
Other	(135,739)	(93,834)	74,726
(Increase) decrease in assets:
Accounts receivable, net	(4,276,906)	(7,128,876)	670,424
Fuel cost under-recovery	1,213,484	1,158,147	(2,093,467)
Materials and supplies	(189,092)	2,563,223	(6,061,005)
Fuel stock	(9,466,767)	0	0
Prepayments	(245,073)	13,635	(663,527)
Other assets	27,937	(2,049,082)	(96,522)
Deferred charges	(4,335,252)	(6,358,154)	(1,511,639)
Increase (decrease) in liabilities:
Accounts payable	1,454,677	1,891,089	(1,321,046)
Consumer deposits	330,849	(1,276,677)	(267,221)
Fuel cost over-recovery	13,710,049	0	(3,511,422)
Accrued interest	(36,266)	793,942	(18,099)
Salaries, wages and benefits	771,512	863,849	777,522
Fuel	(3,531,079)	2,829,619	6,911,480
Other current liabilities	3,094,139	3,011,319	2,701,345
Deferred liabilities	120,204	239,761	(70,335)
Net cash provided by operating activities	43,005,234	40,811,795	39,151,441
Cash flows from investing activities:
Proceeds on sale of Bernice Lake Power Plant	0	9,537,530	0
Investment in associated organizations	663,697	1,153,470	311,593
Investment in restricted cash equivalents	0	(270,000,000)	0
Investment in marketable securities	(10,096,304)	0	0
Proceeds from restricted cash equivalents	120,000,000	150,000,000	0
Extension and replacement of plant	(109,180,413)	(123,679,854)	(73,214,825)
Net cash provided by (used in) investing activities	1,386,980	(232,988,854)	(72,903,232)
Cash flows from financing activities:
Payments for debt issue costs	(1,850,199)	(1,949,027)	(1,493,572)
Proceeds from short-term obligations	24,500,000	76,500,000	47,000,000
Proceeds from long-term obligations	250,000,000	275,000,000	0
Repayments of short-term obligations	(188,000,000)	0	0
Repayments of long-term obligations	(133,360,210)	(152,851,500)	(4,118,029)
Memberships and donations received	55,519	189,385	205,956
Retirement of patronage capital and estate payments	(48,079)	(309,188)	(146,596)
Net receipts on consumer advances for construction	1,240,106	644,794	870,980
Net cash (used in) provided by financing activities	(47,462,863)	197,224,464	42,318,739
Net change in cash and cash equivalents	(3,070,649)	5,047,405	8,566,948
Cash and cash equivalents at beginning of period	17,118,118	12,070,713	3,503,765
Cash and cash equivalents at end of period	14,047,469	17,118,118	12,070,713
Supplemental disclosure of non-cash investing and financing activities:
Retirement of plant	10,405,777	11,317,319	6,666,875
Extension and replacement of plant included in accounts payable	10,620,219	15,561,199	15,919,688
Supplemental disclosure of cash flow information - interest expense paid, net of amounts capitalized	$ 13,092,576	$ 12,590,296	$ 18,057,000