Commitments And Contingencies (Legal And Regulatory Contingencies) (Detail) (USD $)	9 Months Ended		3 Months Ended	9 Months Ended				9 Months Ended		12 Months Ended	9 Months Ended				9 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 San Bruno Explosion [Member]	Sep. 30, 2012 San Bruno Explosion [Member]	Sep. 30, 2012 San Bruno Explosion [Member] San Mateo County Superior Court [Member] Plaintiff	Sep. 30, 2012 Tort Lawsuits [Member] San Bruno Explosion [Member] San Mateo County Superior Court [Member] LegalMatter	Sep. 30, 2012 Class Action Lawsuits [Member] San Bruno Explosion [Member] San Mateo County Superior Court [Member] LegalMatter	Sep. 30, 2012 Attorney General Unapproved [Member]	Sep. 30, 2012 PGE Corporation And Utility [Member]	Dec. 31, 2011 PGE Corporation And Utility [Member]	Sep. 30, 2012 Pacific Gas And Electric Company [Member]	Dec. 31, 2011 Pacific Gas And Electric Company [Member]	Dec. 31, 2010 Pacific Gas And Electric Company [Member]	Dec. 31, 2009 Pacific Gas And Electric Company [Member]	Sep. 30, 2012 Pacific Gas And Electric Company [Member] San Bruno Explosion [Member]	Sep. 30, 2012 Utility [Member]	Sep. 30, 2012 Utility [Member]	Dec. 31, 2011 Utility [Member]
Loss Contingencies [Line Items]
Accrued legal liabilities		$ 52,000,000							$ 32,000,000		$ 184,000,000	$ 277,000,000	$ 214,000,000	$ 0
Penalty due to plat maps being misplaced	17,000,000
Number of self-reports filed with the CPUC	29
Number of gas distribution maps	16
Probable penalty amount									200,000,000	200,000,000
Number of lawsuits						130	2
Number of plaintiffs					420
Number Plaintiffs Settled					70
Cumulative charge			0	80,000,000											455,000,000
Estimated possible additional loss contingency liability			600,000,000	600,000,000											145,000,000
Insurance recoveries for cost incurred related to third-party claims																99,000,000	135,000,000	99,000,000
Utility liability insurance for damages											992,000,000
Utility liability insurance deductible											10,000,000
Costs incurred to build on-site spent nuclear fuel facilities								266,000,000
Utility estimated cost								25,000,000
Utility Proposed Capital Expenditure Recovery											1,400,000,000
Proposed Dissallowed Capital Expenditure Recovery											401,000,000
Capitalized Expenditure											$ 187,000,000