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, 2013 Qualified Pension Benefits [Member]	Dec. 31, 2012 Qualified Pension Benefits [Member]	Jun. 30, 2013 SERP Pension Benefits [Member]	Dec. 31, 2012 SERP Pension Benefits [Member]	Jun. 30, 2013 Other Benefit [Member]	Dec. 31, 2012 Other Benefit [Member]	Jun. 30, 2013 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2013 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Qualified Pension Benefits [Member]	Jun. 30, 2013 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2013 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 PUGET ENERGY [Member] SERP Pension Benefits [Member]	Jun. 30, 2013 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2013 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2012 PUGET ENERGY [Member] Other Benefit [Member]	Jun. 30, 2013 Subsidiaries [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 Subsidiaries [Member] Qualified Pension Benefits [Member]	Jun. 30, 2013 Subsidiaries [Member] Qualified Pension Benefits [Member]	Jun. 30, 2012 Subsidiaries [Member] Qualified Pension Benefits [Member]	Jun. 30, 2013 Subsidiaries [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 Subsidiaries [Member] SERP Pension Benefits [Member]	Jun. 30, 2013 Subsidiaries [Member] SERP Pension Benefits [Member]	Jun. 30, 2012 Subsidiaries [Member] SERP Pension Benefits [Member]	Jun. 30, 2013 Subsidiaries [Member] Other Benefit [Member]	Jun. 30, 2012 Subsidiaries [Member] Other Benefit [Member]	Jun. 30, 2013 Subsidiaries [Member] Other Benefit [Member]	Jun. 30, 2012 Subsidiaries [Member] Other Benefit [Member]
Components of net periodic benefit cost:
Service cost	$ (9,642)	$ (16,926)	$ (749)	$ (1,073)	$ (67)	$ (139)	$ 4,934	$ 4,229	$ 9,643	$ 8,463	$ 375	$ 268	$ 749	$ 537	$ 32	$ 32	$ 67	$ 70	$ 4,934	$ 4,229	$ 9,643	$ 8,463	$ 375	$ 268	$ 749	$ 537	$ 32	$ 32	$ 67	$ 70
Interest cost	(12,377)	(25,986)	(1,023)	(2,152)	(332)	(751)	6,182	6,551	12,377	12,993	511	538	1,022	1,076	155	188	332	375	6,182	6,551	12,377	12,993	511	538	1,022	1,076	155	188	332	375
Expected return on plan assets							(9,696)	(9,101)	(19,548)	(18,102)	0	0	0	0	(109)	(109)	(218)	(218)	(10,094)	(10,434)	(20,343)	(20,767)	0	0	0	0	(109)	(109)	(218)	(218)
Amortization of prior service cost							(495)	(495)	(990)	(990)	(4)	0	(9)	0	0	0	0	0	(393)	(393)	(787)	(787)	(4)	74	(8)	146	8	9	14	18
Amortization of net loss (gain)							794	234	1,444	384	365	176	731	351	18	17	34	27	5,221	3,790	10,306	7,508	548	358	1,096	716	(108)	(63)	(142)	(122)
Amortization of transition obligation																			0	0	0	0	0	0	0	0	0	12	0	25
Defined Benefit Plan, Net Periodic Benefit Cost							$ 1,719	$ 1,418	$ 2,926	$ 2,748	$ 1,247	$ 982	$ 2,493	$ 1,964	$ 96	$ 128	$ 215	$ 254	$ 5,850	$ 3,743	$ 11,196	$ 7,410	$ 1,430	$ 1,238	$ 2,859	$ 2,475	$ (22)	$ 69	$ 53	$ 148