Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Allowance for doubtful accounts	$ 84	$ 87
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares outstanding	441,509,054	430,718,293
Pacific Gas And Electric Company [Member]
Allowance for doubtful accounts	$ 84	$ 87
Common stock, par value	$ 5	$ 5
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares outstanding	264,374,809	264,374,809