CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2011
ASSETS
Construction work in progress	$ 831,966	$ 766,035
Current assets:
Allowance for doubtful accounts	9,502	9,932
Common shareholder’s equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000	1,000
Common stock, shares outstanding (in shares)	200	200
PUGET SOUND ENERGY, INC. [Member]
ASSETS
Construction work in progress	831,966	766,035
Current assets:
Allowance for doubtful accounts	$ 9,502	$ 9,932
Common shareholder’s equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares outstanding (in shares)	85,903,791	85,903,791