Accounting for Derivative Instruments and Hedging Activities Recognized in Other Comprehensive Income (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
PUGET ENERGY [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Hedge Loss to be Reclassified within Twelve Months	$ (4,100,000)
PUGET SOUND ENERGY, INC. [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Hedge Loss to be Reclassified within Twelve Months	(2,200,000)
Cash Flow Hedging [Member] | PUGET ENERGY [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(1,150,000)	(3,559,000)
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(1,314,000)	(3,859,000)
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Electric generation fuel [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	100,000
Cash Flow Hedging [Member] | PUGET ENERGY [Member] | Purchased electricity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	164,000	200,000
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2,908,000)	(3,080,000)
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(122,000)	(122,000)
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Electric generation fuel [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	97,000
Cash Flow Hedging [Member] | PUGET SOUND ENERGY, INC. [Member] | Purchased electricity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (2,786,000)	$ (3,055,000)