Retirement Benefits Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2012 Qualified Pension Benefits [Member]	Dec. 31, 2011 Qualified Pension Benefits [Member]	Jun. 30, 2012 SERP Pension Benefits [Member]	Dec. 31, 2011 SERP Pension Benefits [Member]	Jun. 30, 2012 Other Benefit [Member]	Dec. 31, 2011 Other Benefit [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2011 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2011 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2011 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2011 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2011 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2011 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2012 PUGET SOUND ENERGY, INC. [Member] Qualified Pension Benefits [Member]	Jun. 30, 2011 PUGET SOUND ENERGY, INC. [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 PUGET SOUND ENERGY, INC. [Member] Qualified Pension Benefits [Member]	Jun. 30, 2011 PUGET SOUND ENERGY, INC. [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 PUGET SOUND ENERGY, INC. [Member] SERP Pension Benefits [Member]	Jun. 30, 2011 PUGET SOUND ENERGY, INC. [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 PUGET SOUND ENERGY, INC. [Member] SERP Pension Benefits [Member]	Jun. 30, 2011 PUGET SOUND ENERGY, INC. [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 PUGET SOUND ENERGY, INC. [Member] Other Benefit [Member]	Jun. 30, 2011 PUGET SOUND ENERGY, INC. [Member] Other Benefit [Member]	Jun. 30, 2012 PUGET SOUND ENERGY, INC. [Member] Other Benefit [Member]	Jun. 30, 2011 PUGET SOUND ENERGY, INC. [Member] Other Benefit [Member]
Components of net periodic benefit cost:
Service cost	$ (8,463)	$ (15,822)	$ (537)	$ (1,241)	$ (70)	$ (113)	$ 4,229	$ 4,059	$ 8,463	$ 8,119	$ 268	$ 310	$ 537	$ 620	$ 32	$ 31	$ 70	$ 62	$ 4,229	$ 4,059	$ 8,463	$ 8,119	$ 268	$ 310	$ 537	$ 620	$ 32	$ 31	$ 70	$ 62
Interest cost	(12,993)	(26,263)	(1,076)	(2,192)	(375)	(807)	6,551	6,630	12,993	13,259	538	548	1,076	1,096	188	204	375	409	6,551	6,630	12,993	13,259	538	548	1,076	1,096	188	204	375	409
Expected return on plan assets							(9,101)	(8,860)	(18,102)	(17,720)	0	0	0	0	(109)	(125)	(218)	(250)	(10,434)	(11,056)	(20,767)	(22,112)	0	0	0	0	(109)	(125)	(217)	(250)
Amortization of prior service cost							(495)	(495)	(990)	(990)	0	0	0	0	0	0	0	0	(393)	(394)	(787)	(786)	74	141	146	281	9	16	18	31
Amortization of net loss (gain)							234	0	384	0	176	90	351	180	17	1	27	1	3,790	2,695	7,508	5,389	358	298	716	598	(63)	(109)	(123)	(217)
Amortization of transition obligation																			0	0	0	0	0	0	0	0	12	13	25	25
Net periodic benefit cost							$ 1,418	$ 1,334	$ 2,748	$ 2,668	$ 982	$ 948	$ 1,964	$ 1,896	$ 128	$ 111	$ 254	$ 222	$ 3,743	$ 1,934	$ 7,410	$ 3,869	$ 1,238	$ 1,297	$ 2,475	$ 2,595	$ 69	$ 30	$ 148	$ 60