CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Utility plant:
Electric plant	$ 6,187,458	$ 6,067,672
Gas plant	2,274,653	2,238,741
Common plant	426,757	418,236
Less: Accumulated depreciation and amortization	(745,821)	(674,782)
Net utility plant	8,143,047	8,049,867
Other property and investments:
Goodwill	1,656,513	1,656,513
Investment in exchange power contract	18,515	19,396
Other property and investments	122,979	123,352
Total other property and investments	1,798,007	1,799,261
Current assets:
Cash and cash equivalents	70,464	37,235
Restricted cash	4,241	4,183
Accounts receivable, net of allowance for doubtful accounts	325,416	336,530
Unbilled revenue	169,825	191,150
Materials and supplies, at average cost	84,588	76,068
Fuel and gas inventory, at average cost	76,903	100,491
Unrealized gain on derivative instruments	5,424	6,647
Income taxes	9,719	11,553
Prepaid expense and other	16,809	13,969
Power contract acquisition adjustment gain	46,153	65,096
Deferred income taxes	107,083	101,934
Total current assets	916,625	944,856
Other long-term and regulatory assets:
Regulatory asset for deferred income taxes	64,022	62,304
Power cost adjustment mechanism	1,073	6,818
Regulatory assets related to power contracts	41,129	46,202
Other regulatory assets	811,546	766,825
Unrealized gain on derivative instruments	9,049	10,084
Power contract acquisition adjustment gain	499,263	517,740
Other	185,501	180,753
Total other long-term and regulatory assets	1,611,583	1,590,726
Total assets	12,469,262	12,384,710
Capitalization:
Common stock	0	0
Additional paid-in capital	3,308,953	3,308,957
Earnings reinvested in the business	111,358	22,873
Accumulated other comprehensive income (loss), net of tax	(28,701)	(30,907)
Total common shareholder's equity	3,391,610	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	1,809,000	1,793,000
Debt discount and other	(273,272)	(289,493)
Total long-term debt	5,309,588	5,277,367
Total capitalization	8,701,198	8,578,290
Current liabilities:
Accounts payable	241,700	339,361
Short-term debt	38,000	25,000
Purchased gas adjustment liability	56,150	25,940
Accrued expenses:
Taxes	104,604	90,727
Salaries and wages	26,019	40,892
Interest	70,821	69,329
Unrealized loss on derivative instruments	357,804	327,089
Power contract acquisition adjustment loss	4,201	8,547
Other	74,244	74,409
Total current liabilities	973,543	1,001,294
Long-term and regulatory liabilities:
Deferred income taxes	1,194,374	1,153,755
Unrealized loss on derivative instruments	162,546	196,558
Regulatory liabilities	363,362	346,225
Regulatory liabilities related to power contracts	545,416	582,836
Power contract acquisition adjustment loss	36,928	37,655
Other deferred credits	491,895	488,097
Total long-term and regulatory liabilities	2,794,521	2,805,126
Commitments and contingencies
Total capitalization and liabilities	12,469,262	12,384,710
PUGET SOUND ENERGY, INC. [Member]
Utility plant:
Electric plant	8,507,919	8,390,667
Gas plant	2,890,909	2,855,794
Common plant	521,497	518,318
Less: Accumulated depreciation and amortization	(3,777,278)	(3,714,912)
Net utility plant	8,143,047	8,049,867
Other property and investments:
Investment in exchange power contract	18,515	19,396
Other property and investments	113,156	113,528
Total other property and investments	131,671	132,924
Current assets:
Cash and cash equivalents	20,957	31,010
Restricted cash	4,241	4,183
Accounts receivable, net of allowance for doubtful accounts	325,437	336,483
Unbilled revenue	169,825	191,150
Materials and supplies, at average cost	84,588	76,068
Fuel and gas inventory, at average cost	73,696	97,074
Unrealized gain on derivative instruments	5,424	6,647
Income taxes	9,719	11,553
Prepaid expense and other	16,647	13,807
Deferred income taxes	114,517	112,204
Total current assets	825,051	880,179
Other long-term and regulatory assets:
Regulatory asset for deferred income taxes	63,045	61,344
Power cost adjustment mechanism	1,073	6,818
Other regulatory assets	806,377	760,585
Unrealized gain on derivative instruments	9,049	10,084
Other	183,758	183,746
Total other long-term and regulatory assets	1,063,302	1,022,577
Total assets	10,163,071	10,085,547
Capitalization:
Common stock	859	859
Additional paid-in capital	3,246,205	3,246,205
Earnings reinvested in the business	204,984	163,735
Accumulated other comprehensive income (loss), net of tax	(184,161)	(188,579)
Total common shareholder's equity	3,267,887	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	(15)	(15)
Total long-term debt	3,773,845	3,773,845
Total capitalization	7,041,732	6,996,065
Current liabilities:
Accounts payable	241,713	339,568
Short-term debt	38,000	25,000
Short-term note owed to parent	29,998	29,998
Purchased gas adjustment liability	56,150	25,940
Accrued expenses:
Taxes	104,604	90,727
Salaries and wages	26,019	40,892
Interest	56,963	55,843
Unrealized loss on derivative instruments	336,909	301,879
Other	70,549	68,346
Total current liabilities	960,905	978,193
Long-term and regulatory liabilities:
Deferred income taxes	1,168,462	1,115,639
Unrealized loss on derivative instruments	144,752	169,359
Regulatory liabilities	358,488	340,907
Other deferred credits	488,732	485,384
Total long-term and regulatory liabilities	2,160,434	2,111,289
Commitments and contingencies
Total capitalization and liabilities	$ 10,163,071	$ 10,085,547