Fair Value Measurements Carrying Value (Details) (Carrying Value [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2011
PUGET ENERGY [Member]
Assets:
Cash and Cash Equivalents	$ 113,988	$ 135,542
Restricted Cash	3,101	3,700
Notes Receivable and Other	55,397	63,802
Total assets	172,486	203,044
Liabilities:
Short-term Debt	25,000	181,000
Total liabilities	25,000	181,000
PUGET ENERGY [Member] | Level 1 [Member]
Assets:
Cash and Cash Equivalents	0	105,000
Restricted Cash	896	914
Notes Receivable and Other	0	0
Total assets	896	105,914
Liabilities:
Short-term Debt	25,000	181,000
Long Term Debt (variable rate) net of discount	0
Total liabilities	25,000	181,000
PUGET ENERGY [Member] | Level 2 [Member]
Assets:
Cash and Cash Equivalents	113,988	30,542
Restricted Cash	2,205	2,786
Notes Receivable and Other	55,397	63,802
Total assets	171,590	97,130
Liabilities:
Short-term Debt	0	0
Long Term Debt (variable rate) net of discount	0
Total liabilities	0	0
PUGET SOUND ENERGY, INC. [Member]
Assets:
Cash and Cash Equivalents	113,947	135,530
Restricted Cash	3,101	3,700
Notes Receivable and Other	55,397	63,802
Total assets	172,445	203,032
Liabilities:
Short-term Debt	25,000	181,000
Short-term Debt owed by PSE to PE	29,598	29,598
Total liabilities	54,598	210,598
PUGET SOUND ENERGY, INC. [Member] | Level 1 [Member]
Assets:
Cash and Cash Equivalents	0	105,000
Restricted Cash	896	914
Notes Receivable and Other	0	0
Total assets	896	105,914
Liabilities:
Short-term Debt	25,000	181,000
Short-term Debt owed by PSE to PE	0	0
Total liabilities	25,000	181,000
PUGET SOUND ENERGY, INC. [Member] | Level 2 [Member]
Assets:
Cash and Cash Equivalents	113,947	30,530
Restricted Cash	2,205	2,786
Notes Receivable and Other	55,397	63,802
Total assets	171,549	97,118
Liabilities:
Short-term Debt	0	0
Short-term Debt owed by PSE to PE	29,598	29,598
Total liabilities	$ 29,598	$ 29,598