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Earnings Per Share (Tables) | 9 Months Ended
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Sep. 30, 2012
Components of Earnings per Share [Abstract] |
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] | Components of basic and diluted earnings per share were as follows:
| Three Months Ended September 30, |  | Nine Months Ended September 30,
| 2012 |  | 2011 |  | 2012 |  | 2011
Numerator (in millions): |  |  |  |  |  |  |
Net income attributable to Portland General Electric Company common shareholders | $ | 38 |  |  | $ | 27 |  |  | $ | 113 |  |  | $ | 118 |
Denominator (in thousands): |  |  |  |  |  |  |
Weighted-average common shares outstanding—basic | 75,528 |  |  | 75,342 |  |  | 75,486 |  |  | 75,329 |
Dilutive effect of unvested restricted stock units and employee stock purchase plan shares | 13 |  |  | 16 |  |  | 14 |  |  | 16 |
Weighted-average common shares outstanding—diluted | 75,541 |  |  | 75,358 |  |  | 75,500 |  |  | 75,345 |
Earnings per share—basic and diluted | $ | 0.50 |  |  | $ | 0.36 |  |  | $ | 1.49 |  |  | $ | 1.57 |

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- Definition Tabular disclosure of an entity's basic and diluted earnings per share calculations. + References No definition available. + Details
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