Other Allowance for Funds Used During Construction (AFUDC) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Regulatory Assets [Line Items]
Debt AFUDC	$ 4,687	$ 7,597	$ 11,982	$ 12,001
PUGET SOUND ENERGY, INC. [Member]
Regulatory Assets [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Rate			7.80%
Equity AFUDC	5,179	8,299	14,485	12,033
Washington Commision AFUDC	178	365	319	4,271
Total in other income	5,357	8,664	14,804	16,304
Debt AFUDC	4,687	7,597	11,982	12,001
Total AFUDC	$ 10,044	$ 16,261	$ 26,786	$ 28,305
PUGET SOUND ENERGY, INC. [Member] | Non-Project Electric Utiliy Plant [Member]
Regulatory Assets [Line Items]
Useful Life			30 years