CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDER'S EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Predecessor [Member]	Predecessor [Member] Common Stock [Member]	Predecessor [Member] Additional Paid-in Capital [Member]	Predecessor [Member] Earnings Reinvested In The Business [Member]	Predecessor [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Successor [Member]	Successor [Member] Common Stock [Member]	Successor [Member] Additional Paid-in Capital [Member]	Successor [Member] Earnings Reinvested In The Business [Member]	Successor [Member] Accumulated Other Comprehensive Income (Loss) [Member]	PUGET SOUND ENERGY, INC. [Member]	PUGET SOUND ENERGY, INC. [Member] Common Stock [Member]	PUGET SOUND ENERGY, INC. [Member] Additional Paid-in Capital [Member]	PUGET SOUND ENERGY, INC. [Member] Earnings Reinvested In The Business [Member]	PUGET SOUND ENERGY, INC. [Member] Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2008	$ 2,273,201		$ 1,297	$ 2,275,225	$ 259,483	$ (262,804)
Balance (in shares) at Dec. 31, 2008			129,678,489
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		12,756	0	0	12,756	0
Common stock dividend declared	(38,188)		0	0	(38,188)	0
Common stock expense	(455)		0	(455)	0	0
Vesting of employee common stock	1,531		0	1,531	0	0
Other comprehensive income (loss)		(19,312)	0	0	0	(19,312)
Balance at Feb. 05, 2009	2,229,533		1,297	2,276,301	234,051	(282,116)
Balance (in shares) at Feb. 05, 2009			129,678,489
Balance at Dec. 31, 2008												2,249,186	859,038	1,296,005	356,947	(262,804)
Balance (in shares) at Dec. 31, 2008													85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in par value												0	(858,179)	858,179	0	0
Net income												159,252	0	0	159,252	0
Common stock dividend declared												(183,071)	0	0	(183,071)	0
Investment from parent												805,283	0	805,283	0	0
Employee common stock award transferred to liability award												(690)	0	(690)	0	0
Employee stock plan tax windfall												428	0	428	0	0
Other comprehensive income (loss)												52,684	0	0	0	52,684
Balance at Dec. 31, 2009												3,083,072	859	2,959,205	333,128	(210,120)
Balance (in shares) at Dec. 31, 2009													85,903,791
Balance at Feb. 05, 2009	2,229,533
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capitalization at merger	3,308,529							0	3,308,529	0	0
Capitalization at merger (in shares)								200
Net income							174,015	0	0	174,015	0
Common stock dividend declared	(82,991)							0	0	(82,991)	0
Employee stock plan tax windfall	428							0	428	0	0
Other comprehensive income (loss)							23,487	0	0	0	23,487
Balance at Dec. 31, 2009	3,423,468							0	3,308,957	91,024	23,487	3,083,072	859	2,959,205	333,128	(210,120)
Balance (in shares) at Dec. 31, 2009								200					85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	30,311							0	0	30,311	0	26,095	0	0	26,095	0
Common stock dividend declared	(104,311)							0	0	(104,311)	0	(186,733)	0	0	(186,733)	0
Other comprehensive income (loss)	(26,556)							0	0	0	(26,556)	52,473	0	0	0	52,473
Balance at Dec. 31, 2010	3,322,912							0	3,308,957	17,024	(3,069)	2,974,907	859	2,959,205	172,490	(157,647)
Balance (in shares) at Dec. 31, 2010								200					85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	123,290							0	0	123,290	0	204,120	0	0	204,120	0
Common stock dividend declared	(117,441)							0	0	(117,441)	0	(212,875)	0	0	(212,875)	0
Capital Contribution												287,000	0	287,000	0	0
Other comprehensive income (loss)	(27,838)							0	0	0	(27,838)	(30,932)	0	0	0	(30,932)
Balance at Dec. 31, 2011	$ 3,300,923							$ 0	$ 3,308,957	$ 22,873	$ (30,907)	$ 3,222,220	$ 859	$ 3,246,205	$ 163,735	$ (188,579)
Balance (in shares) at Dec. 31, 2011	200							200				85,903,791	85,903,791