Accounting for Derivative Instruments and Hedging Activities Recognized in Other Comprehensive Income (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
PUGET ENERGY [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Hedge Loss to be Reclassified within Twelve Months					$ (6,100,000)
PUGET SOUND ENERGY, INC. [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Hedge Loss to be Reclassified within Twelve Months					(8,300,000)
Cash Flow Hedging [Member] | PUGET ENERGY [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	0	[1]	0	[1]	0	[1]	0	[1]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(11,093,000)	[2]	(24,518,000)	[2]	(14,651,000)	[2]	(31,318,000)	[2]
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(10,905,000)	[2]	(24,246,000)	[2]	(14,763,000)	[2]	(30,758,000)	[2]
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Electric generation fuel [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	0	[2]	(20,000)	[2]	100,000	[2]	(50,000)	[2]
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Purchased electricity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(188,000)	[2]	(252,000)	[2]	12,000	[2]	(510,000)	[2]
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Interest rate contracts: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	0	[1]	0	[1]	0	[1]	0	[1]
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Commodity contracts: Electric derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	0	[1]	0	[1]	0	[1]	0	[1]
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	0	[1]	0	[1]	0	[1]	0	[1]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(4,536,000)	[2]	(5,023,000)	[2]	(7,615,000)	[2]	(24,514,000)	[2]
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(122,000)	[2]	(123,000)	[2]	(244,000)	[2]	(246,000)	[2]
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Electric generation fuel [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(4,414,000)	[2]	(237,000)	[2]	97,000	[2]	(17,109,000)	[2]
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Purchased electricity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	0	[2]	(4,663,000)	[2]	(7,468,000)	[2]	(7,159,000)	[2]
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Interest rate contracts: [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	0	[1]	0	[1]	0	[1]	0	[1]
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Commodity contracts: Electric derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 0	[1]

[1] Changes in OCI are reported in after-tax dollars.

[2] A reclassification of a loss in OCI increases accumulated OCI and decreases earnings. Amounts reported are in pre-tax dollars.