Earnings Per Share (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Numerator (in millions)
Net income sttributable 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

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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Reference 14: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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Reference 15: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

+ References+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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-Glossary Weighted-Average Number of Common Shares Outstanding

-URI http://asc.fasb.org/extlink&oid=6528421

+ Details