Long term debt (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended		3 Months Ended		12 Months Ended
	Dec. 31, 2013	Nov. 30, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Aug. 31, 2013	Apr. 30, 2013
Debt Instrument [Line Items]
Repayments of Long-term Debt			$ 50	$ 50	$ 100	$ 100	$ 73
Long-term Pollution Control Bond	21				21
Pollution Control Bonds Retired					(6)
Proceeds from Issuance of Long-term Debt	50	105	75	150	380	0	0
Debt Instrument, Interest Rate, Stated Percentage	4.84%	4.74%	5.625%	4.47%	4.84%			4.47%	4.45%
First mortgage Bonds - minimum rate	3.46%				3.46%	3.46%
First Mortgage Bonds - maximum rate	9.31%				9.31%	9.31%
Debt, Weighted Average Interest Rate	5.62%				5.62%	5.84%
Pollution Control Revenue Bonds owned by PGE	$ 27				$ 27	$ 21
Long-term Pollution Control Bond, Rate	5.00%				5.00%