CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Utility plant (at original cost, including construction work in progress):
Electric plant	$ 6,336,530	$ 6,067,672
Gas plant	2,314,874	2,238,741
Common plant	439,872	418,236
Less: Accumulated depreciation and amortization	(828,083)	(674,782)
Net utility plant	8,263,193	8,049,867
Other property and investments:
Goodwill	1,656,513	1,656,513
Investment in exchange power contract	17,633	19,396
Other property and investments	116,203	123,352
Total other property and investments	1,790,349	1,799,261
Current assets:
Cash and cash equivalents	16,133	37,235
Restricted cash	3,544	4,183
Accounts receivable, net of allowance for doubtful accounts	233,225	336,530
Unbilled revenue	120,102	191,150
Materials and supplies, at average cost	89,790	76,068
Fuel and gas inventory, at average cost	69,154	100,491
Unrealized gain on derivative instruments	6,973	6,647
Income taxes	9,661	11,553
Prepaid expense and other	18,157	13,969
Power contract acquisition adjustment gain	47,012	65,096
Deferred income taxes	87,931	101,934
Total current assets	701,682	944,856
Other long-term and regulatory assets:
Regulatory asset for deferred income taxes	67,830	62,304
Power cost adjustment mechanism	0	6,818
Regulatory assets related to power contracts	39,227	46,202
Other regulatory assets	866,036	766,825
Unrealized gain on derivative instruments	15,981	10,084
Power contract acquisition adjustment gain	490,354	517,740
Other	82,334	180,753
Total other long-term and regulatory assets	1,561,762	1,590,726
Total assets	12,316,986	12,384,710
Capitalization:
Common stock	0	0
Additional paid-in capital	3,308,957	3,308,957
Earnings reinvested in the business	80,600	22,873
Accumulated other comprehensive income (loss), net of tax	(21,593)	(30,907)
Total common shareholder's equity	3,367,964	3,300,923
Long-term debt:
First mortgage bonds and senior notes	3,362,000	3,362,000
Pollution control bonds	161,860	161,860
Junior subordinated notes	250,000	250,000
Long-term debt	1,834,000	1,793,000
Debt discount and other	(270,227)	(289,493)
Total long-term debt	5,337,633	5,277,367
Total capitalization	8,705,597	8,578,290
Current liabilities:
Accounts payable	214,847	339,361
Short-term debt	38,000	25,000
Purchased gas adjustment liability	49,611	25,940
Accrued expenses:
Taxes	79,892	90,727
Salaries and wages	29,058	40,892
Interest	69,480	69,329
Unrealized loss on derivative instruments	277,246	327,089
Power contract acquisition adjustment loss	4,050	8,547
Other	69,381	74,409
Total current liabilities	831,565	1,001,294
Long-term and regulatory liabilities:
Deferred income taxes	1,202,949	1,153,755
Unrealized loss on derivative instruments	113,209	196,558
Power cost adjustment mechanism	19,433	0
Regulatory liabilities	375,748	346,225
Regulatory liabilities related to power contracts	537,366	582,836
Power contract acquisition adjustment loss	35,177	37,655
Other deferred credits	495,942	488,097
Total long-term and regulatory liabilities	2,779,824	2,805,126
Commitments and contingencies
Total capitalization and liabilities	12,316,986	12,384,710
PUGET SOUND ENERGY, INC. [Member]
Utility plant (at original cost, including construction work in progress):
Electric plant	8,655,056	8,390,667
Gas plant	2,930,189	2,855,794
Common plant	526,925	518,318
Less: Accumulated depreciation and amortization	(3,848,976)	(3,714,912)
Net utility plant	8,263,194	8,049,867
Other property and investments:
Investment in exchange power contract	17,633	19,396
Other property and investments	106,379	113,528
Total other property and investments	124,012	132,924
Current assets:
Cash and cash equivalents	14,630	31,010
Restricted cash	3,544	4,183
Accounts receivable, net of allowance for doubtful accounts	233,338	336,483
Unbilled revenue	120,102	191,150
Materials and supplies, at average cost	89,790	76,068
Fuel and gas inventory, at average cost	65,936	97,074
Unrealized gain on derivative instruments	6,973	6,647
Income taxes	9,661	11,553
Prepaid expense and other	17,997	13,807
Deferred income taxes	100,916	112,204
Total current assets	662,887	880,179
Other long-term and regulatory assets:
Regulatory asset for deferred income taxes	66,841	61,344
Power cost adjustment mechanism	0	6,818
Other regulatory assets	861,784	760,585
Unrealized gain on derivative instruments	15,981	10,084
Other	76,492	183,746
Total other long-term and regulatory assets	1,021,098	1,022,577
Total assets	10,071,191	10,085,547
Capitalization:
Common stock	859	859
Additional paid-in capital	3,246,205	3,246,205
Earnings reinvested in the business	219,994	163,735
Accumulated other comprehensive income (loss), net of tax	(179,986)	(188,579)
Total common shareholder's equity	3,287,072	3,222,220
Long-term debt:
First mortgage bonds and senior notes	3,362,000	3,362,000
Pollution control bonds	161,860	161,860
Junior subordinated notes	250,000	250,000
Debt discount and other	(14)	(15)
Total long-term debt	3,773,846	3,773,845
Total capitalization	7,060,918	6,996,065
Current liabilities:
Accounts payable	214,937	339,568
Short-term debt	38,000	25,000
Short-term note owed to parent	29,998	29,998
Purchased gas adjustment liability	49,611	25,940
Accrued expenses:
Taxes	79,892	90,727
Salaries and wages	29,058	40,892
Interest	55,964	55,843
Unrealized loss on derivative instruments	271,023	301,879
Other	65,763	68,346
Total current liabilities	834,246	978,193
Long-term and regulatory liabilities:
Deferred income taxes	1,192,086	1,115,639
Unrealized loss on derivative instruments	99,285	169,359
Power cost adjustment mechanism	19,433	0
Regulatory liabilities	371,096	340,907
Other deferred credits	494,127	485,384
Total long-term and regulatory liabilities	2,176,027	2,111,289
Commitments and contingencies
Total capitalization and liabilities	$ 10,071,191	$ 10,085,547