Long-term Debt Schedule of Long Term Debt Instruments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
First Mortgage Bonds, rates range from 3.46% to 9.31%, with a weighted average rate of 5.83% in 2011 and 5.85% in 2010, due at various dates through 2040	$ 1,615	$ 1,678
Pollution Control Revenue Bonds:
Port of Morrow, Oregon, 5% rate, due 2033	23	23
City of Forsyth, Montana, 5% rate, due 2033	119	119
Port of St. Helens, Oregon, 5.25% rate, due in 2014	0	10
Total Pollution Control Revenue Bonds	142	152
Pollution Control Revenue Bonds owned by PGE	(21)	(21)
Unamortized debt discount	(1)	(1)
Total long-term debt	1,735	1,808
Less: current portion of long-term debt	(100)	(10)
Long-term debt, net of current portion	$ 1,635	$ 1,798