Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Electric plant:
In service	$ 7,377,355	$ 7,335,866
Less: Accumulated provision for depreciation	(3,364,573)	(3,328,585)
Total in service	4,012,782	4,007,281
Nuclear fuel, at amortized cost	300,736	284,205
Construction work in progress	1,890,264	1,784,264
Total electric plant	6,203,782	6,075,750
Investments and funds:
Nuclear decommissioning trust fund	287,930	268,597
Deposit on Rocky Mountain transactions	134,274	132,048
Investment in associated companies	57,407	57,626
Long-term investments	76,083	80,055
Restricted cash	51,741	43,070
Other, at cost	1,040	3,564
Total investments and funds	608,475	584,960
Current assets:
Cash and cash equivalents	402,368	443,671
Restricted cash	613	613
Restricted short-term investments	110,526	106,676
Receivables	139,359	124,650
Inventories, at average cost	246,284	246,795
Prepayments and other current assets	14,037	15,562
Total current assets	913,187	937,967
Deferred charges:
Deferred debt expense, being amortized	66,368	67,470
Regulatory assets	338,386	351,547
Other	34,609	61,135
Total deferred charges	439,363	480,152
Total assets	8,164,807	8,078,829
Capitalization:
Patronage capital and membership fees	647,209	633,689
Accumulated other comprehensive margin	1,327	618
Total patronage capital and membership fees and accumulated other comprehensive margin (deficit)	648,536	634,307
Long-term debt	5,604,783	5,562,925
Obligation under capital leases	144,243	146,781
Obligation under Rocky Mountain transactions	134,274	132,048
Total capitalization	6,531,836	6,476,061
Current liabilities:
Long-term debt and capital leases due within one year	159,737	172,818
Short-term borrowings	585,014	461,093
Accounts payable	80,159	134,095
Accrued interest	69,262	91,106
Accrued taxes	8,414	21,118
Member power bill prepayments, current	66,214	66,819
Other current liabilities	27,707	25,080
Total current liabilities	996,507	972,129
Deferred credits and other liabilities:
Gain on sale of plant, being amortized	25,494	26,113
Asset retirement obligations	303,615	298,758
Member power bill prepayments, non-current	41,675	35,500
Power sale agreement, being amortized	51,201	54,816
Regulatory liabilities	161,478	164,000
Other	53,001	51,452
Total deferred credits and other liabilities	636,464	630,639
Total equity and liabilities	$ 8,164,807	$ 8,078,829