Fair Value Measurements Valuation Technicques for Measurement with Unobservable Inputs (Details) (USD $)				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2013 Commodity Contract [Member]	Dec. 31, 2012 Commodity Contract [Member]	Mar. 31, 2013 Electric portfolio [Member] Discounted cash flow [Member] Low [Member]	Mar. 31, 2013 Electric portfolio [Member] Discounted cash flow [Member] High [Member]	Mar. 31, 2013 Electric portfolio [Member] Discounted cash flow [Member] Weighted Average [Member]	Mar. 31, 2013 Natural gas portfolio [Member] Discounted cash flow [Member] Low [Member]	Mar. 31, 2013 Natural gas portfolio [Member] Discounted cash flow [Member] High [Member]	Mar. 31, 2013 Natural gas portfolio [Member] Discounted cash flow [Member] Weighted Average [Member]	Mar. 31, 2013 Level 3 [Member] Fair Value, Measurements, Recurring [Member] PUGET ENERGY [Member]	Dec. 31, 2011 Level 3 [Member] Fair Value, Measurements, Recurring [Member] PUGET ENERGY [Member]	Mar. 31, 2013 Electric portfolio [Member] Level 3 [Member] Fair Value, Measurements, Recurring [Member] PUGET ENERGY [Member] Commodity Contract [Member]	Mar. 31, 2013 Natural gas portfolio [Member] Level 3 [Member] Fair Value, Measurements, Recurring [Member] PUGET ENERGY [Member] Commodity Contract [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets		$ 34,862,000	$ 21,683,000									$ 8,632,000	$ 4,893,000
Derivative Liabilities										0	0	35,074,000	6,427,000
Price (per MWh)				8.48	47.07	33.57
Price (per MMBtu)							3.44	4.91	4.25
Fair Value Measurements, Sensitivity Analysis, Hypothetical Increase or Decrease of Market Prices, Result on Fair Value	$ 20,800,000