CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDER'S EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total USD ($)	Common Stock	Additional Paid-in Capital USD ($)	Earnings Reinvested in the Business USD ($)	Accumulated Other Comprehensive Income (Loss) USD ($)	PUGET SOUND ENERGY, INC. USD ($)	PUGET SOUND ENERGY, INC. Common Stock USD ($)	PUGET SOUND ENERGY, INC. Additional Paid-in Capital USD ($)	PUGET SOUND ENERGY, INC. Earnings Reinvested in the Business USD ($)	PUGET SOUND ENERGY, INC. Accumulated Other Comprehensive Income (Loss) USD ($)
Balance at Dec. 31, 2011	$ 3,300,923		$ 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					85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	273,821			273,821		356,170			356,170
Common stock dividend	(88,594)			(88,594)		(175,625)			(175,625)
Other comprehensive income (loss)	(1,922)				(1,922)	1,381				1,381
Balance at Dec. 31, 2012	3,484,228		3,308,957	208,100	(32,829)	3,404,146	859	3,246,205	344,280	(187,198)
Balance (in shares) at Dec. 31, 2012		200					85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	167,475					179,938
Balance at Mar. 31, 2013
Balance at Dec. 31, 2012	3,484,228		3,308,957	208,100	(32,829)	3,404,146	859	3,246,205	344,280	(187,198)
Balance (in shares) at Dec. 31, 2012		200					85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	285,728			285,728		356,129			356,129
Common stock dividend	(170,821)			(170,821)		(410,977)			(410,977)
Other comprehensive income (loss)	80,544				80,544	91,459				91,459
Balance at Dec. 31, 2013	3,679,679		3,308,957	323,007	47,715	3,440,757	859	3,246,205	289,432	(95,739)
Balance (in shares) at Dec. 31, 2013	200	200				85,903,791,000	85,903,791
Balance at Sep. 30, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	108,808					122,923
Balance at Dec. 31, 2013	3,679,679		3,308,957			3,440,757	859	3,246,205
Balance (in shares) at Dec. 31, 2013	200	200				85,903,791,000	85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	107,592					121,083
Balance at Mar. 31, 2014
Balance at Dec. 31, 2013	3,679,679		3,308,957	323,007	47,715	3,440,757	859	3,246,205	289,432	(95,739)
Balance (in shares) at Dec. 31, 2013	200	200				85,903,791,000	85,903,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	171,835			171,835		236,614			236,614
Common stock dividend	(223,428)			(223,428)		(323,424)			(323,424)
Other comprehensive income (loss)	(84,758)				(84,758)	(75,218)				(75,218)
Balance at Dec. 31, 2014	3,543,328		3,308,957	271,414	(37,043)	3,278,729	859	3,246,205	202,622	(170,957)
Balance (in shares) at Dec. 31, 2014	200	200				85,903,791	85,903,791
Balance at Sep. 30, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	36,088					54,640
Balance at Dec. 31, 2014	$ 3,543,328		$ 3,308,957			$ 3,278,729	$ 859	$ 3,246,205
Balance (in shares) at Dec. 31, 2014	200	200				85,903,791	85,903,791