Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Electric plant:
In service	$ 7,426,383	$ 7,335,866
Less: Accumulated provision for depreciation	(3,437,932)	(3,328,585)
Total in service	3,988,451	4,007,281
Nuclear fuel, at amortized cost	295,761	284,205
Construction work in progress	2,108,896	1,784,264
Total electric plant	6,393,108	6,075,750
Investments and funds:
Nuclear decommissioning trust fund	296,623	268,597
Deposit on Rocky Mountain transactions	42,932	132,048
Investment in associated companies	57,713	57,626
Long-term investments	75,910	80,055
Restricted cash	7,813	43,070
Other, at cost	1,040	3,564
Total investments and funds	482,031	584,960
Current assets:
Cash and cash equivalents	437,810	443,671
Restricted cash	156	613
Restricted short-term investments	63,868	106,676
Receivables	126,805	124,650
Inventories, at average cost	235,186	246,795
Prepayments and other current assets	15,977	15,562
Total current assets	879,802	937,967
Deferred charges:
Deferred debt expense, being amortized	63,026	67,470
Regulatory assets	357,600	351,547
Other	67,935	61,135
Total deferred charges	488,561	480,152
Total assets	8,243,502	8,078,829
Capitalization:
Patronage capital and membership fees	681,830	633,689
Accumulated other comprehensive margin	1,488	618
Total patronage capital and membership fees and accumulated other comprehensive margin (deficit)	683,318	634,307
Long-term debt	5,591,898	5,562,925
Obligation under capital leases	140,067	146,781
Obligation under Rocky Mountain transactions	42,932	132,048
Total capitalization	6,458,215	6,476,061
Current liabilities:
Long-term debt and capital leases due within one year	169,282	172,818
Short-term borrowings	757,315	461,093
Accounts payable	60,711	134,095
Accrued interest	71,026	91,106
Accrued taxes	25,048	21,118
Member power bill prepayments, current	65,573	66,819
Other current liabilities	14,992	25,080
Total current liabilities	1,163,947	972,129
Deferred credits and other liabilities:
Gain on sale of plant, being amortized	24,257	26,113
Asset retirement obligations	314,378	298,758
Member power bill prepayments, non-current	48,973	35,500
Power sale agreement, being amortized	43,970	54,816
Regulatory liabilities	133,383	164,000
Other	56,379	51,452
Total deferred credits and other liabilities	621,340	630,639
Total equity and liabilities	$ 8,243,502	$ 8,078,829