Earnings Per Share (Reconciliation Of PG&E Corporation's Income Available For Common Shareholders And Weighted Average Common Shares Outstanding For Calculating Diluted EPS) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Income available for common shareholders	$ 239	$ 233
Weighted average common shares outstanding, basic	434	414
Employee share-based compensation	1	2
Weighted average common shares outstanding, diluted	435	416
Total earnings per common share, diluted	$ 0.55	$ 0.56

Earnings Per Share (Reconciliation Of PG&E Corporation's Income Available For Common Shareholders And Weighted Average Common Shares Outstanding For Calculating Diluted EPS) (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified

3 Months Ended

Mar. 31, 2013

Mar. 31, 2012

Income available for common shareholders

$ 239

$ 233

Weighted average common shares outstanding, basic

434

414

Employee share-based compensation

Weighted average common shares outstanding, diluted

435

416

Total earnings per common share, diluted

$ 0.55

$ 0.56

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ 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

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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+ Details