Commitments And Contingencies (Legal And Regulatory Contingencies) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended						3 Months Ended	12 Months Ended	9 Months Ended					9 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 San Bruno Explosion [Member]	Sep. 30, 2013 San Bruno Explosion [Member] San Mateo County Superior Court [Member] plaintiffs	Sep. 30, 2013 Tort Lawsuits [Member] San Bruno Explosion [Member] San Mateo County Superior Court [Member] lawsuits	Sep. 30, 2013 Pipeline Safety Enhancement Plan Costs Approved, Implementation of Operational Remedies, Future Pipeline Safety Enhancement Plan Costs [Member]	Sep. 30, 2013 PGE Corporation And Utility [Member]	Dec. 31, 2012 PGE Corporation And Utility [Member]	Sep. 30, 2013 Pacific Gas And Electric Company [Member]	Sep. 30, 2012 Pacific Gas And Electric Company [Member]	Dec. 31, 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]	Sep. 30, 2013 Pacific Gas And Electric Company [Member] San Bruno Explosion [Member]	Sep. 30, 2013 Utility [Member]	Sep. 30, 2013 Utility [Member] mi	Dec. 31, 2012 Utility [Member]	Sep. 30, 2013 Utility [Member] State General Fund [Member]	Sep. 30, 2013 Utility [Member] Pipeline Safety Enhancement Plan Costs Previously Disallowed By CPUC [Member]	Sep. 30, 2013 Utility [Member] Strength Testing Program [Member] Original Application [Member] mi	Sep. 30, 2013 Utility [Member] Strength Testing Program [Member] Updated Application [Member] mi	Sep. 30, 2013 Utility [Member] Pipeline Replacement Program [Member] Original Application [Member] mi	Sep. 30, 2013 Utility [Member] Pipeline Replacement Program [Member] Updated Application [Member] mi
Loss Contingencies [Line Items]
Accrued legal liabilities							$ 36	$ 34	$ 176		$ 146	$ 277	$ 214
Number of self-reports filed with the CPUC	58
Probable penalty amount							200	200
Disallowed capital expenditures	196	0					196	353	196	0
Number of lawsuits					165
Number of plaintiffs				525
Cumulative charge														565
Cumulative payments														389
Estimated maximum amount for third party claims for San Bruno			110
Utility liability insurance for damages														992
Utility liability insurance deductible														10
Cumulative insurance recoveries for cost incurred related to third-party claims															25	70	284
Legal expenses														84
Number of CPUC investigative enforcement proceedings pending	3
SED issued citations	1
CPUC Issued OCS	2
SED recommended penalty						1,515												300	435
DRA and TURN Recommended Penalties						12,700
Total penalty recommended by various parties															2,250	2,250
City of San Bruno recommended funding for a Peninsula Emergency Response Consortium															150	150
City of San Bruno recommended funding for the California Pipeline Safety Trust and an independent monitor to oversee the implementation of the recommended remedial operational measures															100	100
TURN recommended funding to implement remedial measures and to pay for an independent monitor															50	50
Capitalized PSEP Costs							170
Unrecognized tax benefits	350
Natural Gas Pipeline Transmission Miles																6,750				783	658	186	143
SED imposed fine															$ 140	$ 140