Commitments and Guarantees Schdule of Long term contracts for purchase of electric power (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 MW	Dec. 31, 2010	Dec. 31, 2009
Priest Rapids and Wanapum [Member]
Long-term Contract for Purchase of Electric Power [Line Items]
Revenue Bonds issued by the Public Utility Districts	$ 917
PGE Share of Output	8.80%
PGE Share of Capacity	176
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	Dec. 31, 2052
commitment costs	14	10	17
Wells [Member]
Long-term Contract for Purchase of Electric Power [Line Items]
Revenue Bonds issued by the Public Utility Districts	259
PGE Share of Output	19.40%
PGE Share of Capacity	159
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	Dec. 31, 2018
commitment costs	10	7	8
Portland Hydro [Member]
Long-term Contract for Purchase of Electric Power [Line Items]
Revenue Bonds issued by the Public Utility Districts	11
PGE Share of Output	100.00%
PGE Share of Capacity	36
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	Dec. 31, 2017
commitment costs	$ 4	$ 4	$ 4