Earnings Per Share (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Numerator (in millions)
Net income sttributable to Portland General Electric Company common shareholders	$ 26	$ 22	$ 75	$ 91
Denominator (in thousands)
Weighted Average Common Shares Outstanding, Basic	75,507	75,326	75,465	75,322
Dilutive effect of unvested restricted stock units and employee stock purchase plan shares	10	75	14	47
Weighted Average Common Shares Outstanding, Diluted	75,517	75,401	75,479	75,369
Earnings per share - basic and diluted	$ 0.34	$ 0.29	$ 0.99	$ 1.21

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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-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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

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Reference 16: 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

-Publisher FASB

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-Glossary Weighted-Average Number of Common Shares Outstanding

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

+ Details