CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended		11 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009 Successor [Member]	Feb. 05, 2009 Predecessor [Member]	Dec. 31, 2011 PUGET SOUND ENERGY, INC. [Member]	Dec. 31, 2010 PUGET SOUND ENERGY, INC. [Member]	Dec. 31, 2009 PUGET SOUND ENERGY, INC. [Member]
Operating activities:
Net income (loss)	$ 123,290	$ 30,311	$ 174,015	$ 12,756	$ 204,120	$ 26,095	$ 159,252
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	299,597	292,634	242,477	21,773	299,597	292,634	269,386
Amortization	72,381	71,572	63,466	4,969	72,381	71,572	63,466
Conservation amortization	107,646	90,109	58,875	7,592	107,646	90,109	66,466
Deferred income taxes and tax credits, net	33,318	(32,955)	244,216	(512)	77,757	(16,284)	194,494
Net unrealized (gain) loss on derivative instruments	45,043	50,495	(156,601)	3,867	54,146	166,953	(1,254)
Derivative contracts classified as financing activities due to merger	182,710	371,621	524,397	0
AFUDC - equity	(32,431)	(12,677)	(4,108)	(69)	(32,431)	(12,677)	(4,177)
Pension funding	(5,000)	(12,000)	(18,400)	0	(5,000)	(12,000)	(18,400)
Regulatory assets	26,631	26,198	(5,276)	(1,668)	26,631	26,198	(5,821)
Regulatory liabilities	21,031	28,821	18,436	(126)	21,031	28,821	18,327
Other long-term assets	(59,094)	(50,009)	(17,963)	2,845	(60,046)	(48,258)	(13,757)
Other long-term liabilities	46,473	31,944	(12,536)	1,141	28,818	1,701	(19,003)
Change in certain current assets and liabilities:
Accounts receivable and unbilled revenue	(5,977)	7,261	91,515	(31,332)	(6,204)	7,584	64,349
Materials and supplies	8,154	(19,378)	808	(3,388)	8,154	(19,618)	(2,580)
Fuel and gas inventory	(4,852)	3,591	16,786	7,605	(4,852)	3,591	24,391
Income taxes	64,630	58,434	(133,773)	18,277	50,561	37,834	(82,630)
Prepayments and other	605	(2,345)	5,745	(3,295)	605	(2,345)	2,353
Purchased gas adjustment	31,932	(55,579)	38,984	1,711	31,932	(55,579)	40,695
Accounts payable	1,098	(26,396)	(85,073)	(40,203)	688	(25,780)	(35,205)
Taxes payable	9,222	4,203	4,949	(3,340)	9,222	4,203	(7,339)
Accrued expenses and other	43,921	10,094	(40,369)	59,172	18,666	11,021	7,678
Net cash provided by operating activities	1,010,328	865,949	1,010,570	57,775	903,422	575,775	720,691
Investing activities:
Construction expenditures - excluding equity AFUDC	(976,513)	(859,091)	(726,157)	(49,531)	(976,513)	(859,091)	(775,688)
Energy efficiency expenditures	(94,405)	(95,726)	(82,258)	(4,918)	(94,405)	(95,726)	(87,176)
Treasury grant payment received	0	28,675	0	0	0	28,675	0
Restricted cash	1,287	14,374	(945)	(10)	1,287	14,374	(955)
Other	(7,184)	6,001	26,284	959	9,043	6,001	27,249
Net cash used in investing activities	(1,076,815)	(905,767)	(783,076)	(53,500)	(1,060,588)	(905,767)	(836,570)
Financing activities:
Change in short-term debt and leases, net	(227,651)	141,941	38,807	(151,800)	(227,651)	141,941	(113,286)
Dividends paid	(117,441)	(104,311)	(121,179)	0	(212,875)	(186,733)	(183,071)
Long-term notes and bonds issued	1,382,000	1,025,000	400,211	250,000	595,000	575,000	600,000
Loan from (payment to) parent					7,400	(300)	(3,156)
Redemption of preferred stock	0	0	0	(1,889)	0	0	(1,889)
Redemption of bonds and notes	(769,000)	(675,000)	(158,000)	0	(285,000)	(232,000)	(158,000)
Derivative contracts classified as financing activities due to merger	(182,710)	(371,621)	(524,397)	0
Investment from parent					287,000	0	25,960
Issuance cost of bonds and other	(18,033)	(18,161)	(16,372)	7,133	(12,018)	(10,003)	(10,742)
Net cash provided by (used in) financing activities	67,165	(2,152)	(380,930)	103,444	151,856	287,905	155,816
Net increase (decrease) in cash and cash equivalents	678	(41,970)	(153,436)	107,719	(5,310)	(42,087)	39,937
Cash and cash equivalents at beginning of period	36,557	78,527	231,963	38,526	36,320	78,407	38,470
Cash and cash equivalents at end of period	37,235	36,557	78,527	146,245	31,010	36,320	78,407
Supplemental cash flow information:
Cash payments for interest (net of capitalized interest)	280,847	278,926	247,247	1,239	191,666	198,496	183,652
Cash payments (refunds) for income taxes	$ (64,016)	$ (22,243)	$ (47,740)	$ 0	$ (50,022)	$ (20,632)	$ (44,365)