SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PUGET ENERGY - Condensed Balance Sheets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Other property and investments:
Goodwill	$ 1,656,513		$ 1,656,513
Current assets:
Cash	135,542		37,235		36,557	78,527
Deferred income taxes	53,437		101,934
Total current assets	932,149		944,273
Long-term assets:
Other	95,763		183,394
Total assets	12,801,579		12,407,306		11,958,011
Capitalization and liabilities:
Common equity	3,484,228		3,300,923		3,322,912	3,423,468
Long-term debt	1,834,000		1,793,000
Total capitalization	8,817,428		8,578,290
Current liabilities:
Accounts payable	288,059		339,361
Interest	82,262		69,329
Unrealized loss on derivative instruments	177,519		327,089
Total current liabilities	985,189		1,001,294
Long-term liabilities:
Unrealized loss on derivative instruments	83,276		196,558
Total capitalization and liabilities	12,801,579		12,407,306
PUGET ENERGY
Assets:
Investments in subsidiaries	3,490,206	[1]	3,314,195	[1]
Other property and investments:
Goodwill	1,656,513		1,656,513
Current assets:
Cash	12		6,224		237	119
Receivables from affiliates	29,608	[2]	30,291	[2]
Deferred income taxes	2,300		8,824
Total current assets	31,920		45,339
Long-term assets:
Deferred income taxes	166,896		117,110
Other	20,944		13,544
Total long-term assets	187,840		130,654
Total assets	5,366,479		5,146,701
Capitalization and liabilities:
Common equity	3,484,228		3,300,923
Long-term debt	1,833,959		1,779,844
Total capitalization	5,318,187		5,080,767
Current liabilities:
Accounts payable	212		0
Interest	26,466		13,525
Unrealized loss on derivative instruments	6,571		25,210
Total current liabilities	33,249		38,735
Long-term liabilities:
Unrealized loss on derivative instruments	15,043		27,199
Total long-term liabilities	15,043		27,199
Total capitalization and liabilities	$ 5,366,479		$ 5,146,701

[1] Investment in subsidiaries for successor include Puget Energy business combination accounting adjustments under ASC 805 that are recorded at Puget Energy.

[2] Eliminated in consolidation.