CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Utility plant (including construction work in progress of $1,049,342 and $628,387, respectively)
Electric plant	$ 5,729,509	$ 5,253,786
Gas plant	2,164,404	2,129,200
Common plant	387,256	318,615
Less: Accumulated depreciation and amortization	(556,403)	(429,038)
Net utility plant	7,724,766	7,272,563
Other property and investments:
Goodwill	1,656,513	1,656,513
Investment in exchange power contract	21,160	22,923
Other property and investments	122,106	125,918
Total other property and investments	1,799,779	1,805,354
Current assets
Cash and cash equivalents	22,872	36,557
Restricted cash	4,452	5,470
Accounts receivable, net of allowance for doubtful accounts of $8,136 and $9,784, respectively	259,657	327,615
Unbilled revenue	92,207	194,088
Purchased gas adjustment receivable	0	5,992
Materials and supplies, at average cost	78,997	85,413
Fuel and gas inventory, at average cost	68,196	96,633
Unrealized gain on derivative instruments	9,819	7,500
Income taxes	12,290	76,183
Prepaid expense and other	16,772	14,835
Power contract acquisition adjustment gain	108,650	134,553
Deferred income taxes	57,842	83,086
Total current assets	731,754	1,067,925
Other Longterm And Regulatory Assets [Abstract]
Regulatory assets for deferred income taxes	65,853	73,337
Regulatory asset for PURPA buyout costs	20,314	40,629
Power cost adjustment mechanism	10,601	15,618
Regulatory assets related to power contracts	76,015	116,116
Other regulatory assets	674,938	773,974
Unrealized gain on derivative instruments	8,063	8,233
Power contract acquisition adjustment gain	583,720	624,667
Other	149,873	130,920
Total other long-term and regulatory assets	1,589,377	1,783,494
Total assets	11,845,676	11,929,336
Common shareholder's equity:
Common stock	0	0
Additional paid-in capital	3,308,957	3,308,957
Earnings reinvested in the business	12,799	17,024
Accumulated other comprehensive income (loss), net of tax	16,763	(3,069)
Total common shareholder's equity	3,338,519	3,322,912
Long-term debt
First mortgage bonds and senior notes	3,092,000	2,792,000
Pollution control bonds	161,860	161,860
Junior subordinated notes	250,000	250,000
Long-term debt	1,793,000	1,490,000
Debt discount and other	(295,228)	(311,147)
Total long-term debt	5,001,632	4,382,713
Total capitalization	8,340,151	7,705,625
Current liabilities
Accounts payable	231,450	291,148
Short-term debt	0	247,000
Current maturities of long-term debt	0	260,000
Accrued Expenses [Abstract]
Purchased gas adjustment liability	12,724	0
Taxes	74,779	81,505
Salaries and wages	30,577	34,453
Interest	61,783	59,182
Unrealized loss on derivative instruments	231,622	273,100
Power contract acquisition adjustment loss	36,788	69,915
Other	88,968	114,409
Total current liabilities	768,691	1,430,712
Long-term and regulatory liabilities
Deferred income taxes	1,148,840	1,127,611
Unrealized loss on derivative instruments	131,493	183,135
Regulatory liabilities	316,148	305,936
Regulatory liabilities related to power contracts	692,370	759,220
Power contract acquisition adjustment loss	39,516	46,779
Other deferred credits	408,467	370,318
Total long-term and regulatory liabilities	2,736,834	2,792,999
Commitments and contingencies
Total capitalization and liabilities	11,845,676	11,929,336
Puget Sound Energy Inc.
Utility plant (including construction work in progress of $1,049,342 and $628,387, respectively)
Electric plant	8,059,340	7,586,208
Gas plant	2,782,984	2,752,962
Common plant	493,454	427,227
Less: Accumulated depreciation and amortization	(3,618,735)	(3,509,277)
Net utility plant	7,717,043	7,257,120
Other property and investments:
Investment in exchange power contract	21,160	22,923
Other property and investments	111,934	115,056
Total other property and investments	133,094	137,979
Current assets
Cash and cash equivalents	16,347	36,320
Restricted cash	4,452	5,470
Accounts receivable, net of allowance for doubtful accounts of $8,136 and $9,784, respectively	259,610	327,341
Unbilled revenue	92,207	194,088
Purchased gas adjustment receivable	0	5,992
Materials and supplies, at average cost	77,806	84,222
Fuel and gas inventory, at average cost	63,342	92,222
Unrealized gain on derivative instruments	9,819	7,500
Income taxes	11,718	62,114
Prepaid expense and other	16,566	14,412
Deferred income taxes	68,058	80,215
Total current assets	619,925	909,896
Other Longterm And Regulatory Assets [Abstract]
Regulatory assets for deferred income taxes	65,853	73,337
Regulatory asset for PURPA buyout costs	20,314	40,629
Power cost adjustment mechanism	10,601	15,618
Other regulatory assets	651,336	729,115
Unrealized gain on derivative instruments	8,063	8,233
Other	152,630	138,857
Total other long-term and regulatory assets	908,797	1,005,789
Total assets	9,378,859	9,310,784
Common shareholder's equity:
Common stock	859	859
Additional paid-in capital	3,246,205	2,959,205
Earnings reinvested in the business	162,721	172,490
Accumulated other comprehensive income (loss), net of tax	(138,586)	(157,647)
Total common shareholder's equity	3,271,199	2,974,907
Long-term debt
First mortgage bonds and senior notes	3,092,000	2,792,000
Pollution control bonds	161,860	161,860
Junior subordinated notes	250,000	250,000
Debt discount	(15)	0
Total long-term debt	3,503,845	3,203,860
Total capitalization	6,775,044	6,178,767
Current liabilities
Accounts payable	231,758	291,765
Short-term debt	0	247,000
Short-term note owed to Puget Energy	29,998	22,598
Current maturities of long-term debt	0	260,000
Accrued Expenses [Abstract]
Purchased gas adjustment liability	12,724	0
Taxes	74,779	81,505
Salaries and wages	30,577	34,453
Interest	55,900	54,723
Unrealized loss on derivative instruments	204,827	243,053
Other	58,630	49,661
Total current liabilities	699,193	1,284,758
Long-term and regulatory liabilities
Deferred income taxes	1,092,924	1,034,517
Unrealized loss on derivative instruments	104,472	155,179
Regulatory liabilities	307,704	296,884
Other deferred credits	399,522	360,679
Total long-term and regulatory liabilities	1,904,622	1,847,259
Commitments and contingencies
Total capitalization and liabilities	$ 9,378,859	$ 9,310,784