Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Electric plant:
In service	$ 7,413,780	$ 7,335,866
Less: Accumulated provision for depreciation	(3,400,211)	(3,328,585)
Total in service	4,013,569	4,007,281
Nuclear fuel, at amortized cost	295,764	284,205
Construction work in progress	1,990,396	1,784,264
Total electric plant	6,299,729	6,075,750
Investments and funds:
Nuclear decommissioning trust fund	283,676	268,597
Deposit on Rocky Mountain transactions	136,501	132,048
Investment in associated companies	57,640	57,626
Long-term investments	75,357	80,055
Restricted cash	20,692	43,070
Other, at cost	1,040	3,564
Total investments and funds	574,906	584,960
Current assets:
Cash and cash equivalents	409,321	443,671
Restricted cash	613	613
Restricted short-term investments	63,075	106,676
Receivables	157,373	124,650
Inventories, at average cost	239,204	246,795
Prepayments and other current assets	18,388	15,562
Total current assets	887,974	937,967
Deferred charges:
Deferred debt expense, being amortized	64,992	67,470
Regulatory assets	363,502	351,547
Other	35,892	61,135
Total deferred charges	464,386	480,152
Total assets	8,226,995	8,078,829
Capitalization:
Patronage capital and membership fees	658,087	633,689
Accumulated other comprehensive margin	1,446	618
Total patronage capital and membership fees and accumulated other comprehensive margin (deficit)	659,533	634,307
Long-term debt	5,589,065	5,562,925
Obligation under capital leases	142,682	146,781
Obligation under Rocky Mountain transactions	136,501	132,048
Total capitalization	6,527,781	6,476,061
Current liabilities:
Long-term debt and capital leases due within one year	165,909	172,818
Short-term borrowings	648,122	461,093
Accounts payable	72,318	134,095
Accrued interest	83,507	91,106
Accrued taxes	16,729	21,118
Member power bill prepayments, current	56,763	66,819
Other current liabilities	19,024	25,080
Total current liabilities	1,062,372	972,129
Deferred credits and other liabilities:
Gain on sale of plant, being amortized	24,876	26,113
Asset retirement obligations	309,640	298,758
Member power bill prepayments, non-current	37,225	35,500
Power sale agreement, being amortized	47,585	54,816
Regulatory liabilities	162,478	164,000
Other	55,038	51,452
Total deferred credits and other liabilities	636,842	630,639
Total equity and liabilities	$ 8,226,995	$ 8,078,829