CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Parent [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$ 0	$ 0	$ (31,325)
Other comprehensive income (loss):
Net tax on reclassification of net unrealized loss on interest rate swaps during the period, tax	6,234	13,700	11,860
Net unrealized gain (loss) from pension and postretirement plans, tax	(7,469)	(29,522)	2,842
Reclassification of net unrealized loss on energy derivative instruments during the period, tax	200	832	2,380
PUGET SOUND ENERGY, INC.
Other comprehensive income (loss):
Net unrealized gain (loss) from pension and postretirement plans, tax	(3,911)	(28,474)	2,446
Reclassification of net unrealized loss on energy derivative instruments during the period, tax	4,500	11,673	26,140
Amortization of treasury interest rate swaps to earnings, tax	$ 171	$ 171	$ 171