Earnings Per Share Components of Earnings Per Share (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator (in millions)
Net income attributable to Portland General Electric Company common shareholders	$ 31	$ 38	$ 58	$ 113
Denominator
Weighted Average Common Shares Outstanding-Basic	77,637	75,528	76,401	75,486
Dilutive effect of unvested restricted stock units and employee stock purchase plan shares	693	13	302	14
Weighted Average Common Shares Outstanding-Diluted	78,330	75,541	76,703	75,500
Earnings Per Share, Basic and Diluted	$ 0.40	$ 0.50	$ 0.76	$ 1.49