Equity (Changes In Equity) (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 20, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Balance at December 31, 2011				$ 12,101
Balance at December 31, 2011				12,353
Comprehensive income		372	211	865	797
Common stock issued	254			720
Share-based compensation expense				41
Common stock dividends declared				(584)
Preferred stock dividend requirement of subsidiary		(3)	(3)	(10)	(10)
Balance at September 30, 2012		13,133		13,133
Balance at September 30, 2012		13,385		13,385
Pacific Gas And Electric Company [Member]
Balance at December 31, 2011				12,384
Comprehensive income		348	204	824	782
Share-based compensation expense				1
Common stock dividends declared				(537)
Preferred stock dividend requirement		(3)	(3)	(10)	(10)
Equity contributions				715	350
Balance at September 30, 2012		$ 13,377		$ 13,377