Commitments And Contingencies (Legal And Regulatory Contingencies) (Detail) (USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Loss Contingencies [Line Items]
Accrued legal liabilities	$ 39,000,000			$ 55,000,000
Disallowed capital expenditures	(53,000,000)		0
Unrecognized Tax Benefits	370,000,000
Amount of capitalized PSEP costs included in Property, Plant, and Equipment	600,000,000
Payment To State General Fund	100,000,000			200,000,000
Bill Credit to Natural Gas Customers	400,000,000
CPUC Remedial Measures	0	[1]
CPUC Disallowed Future Spending	850,000,000
Disallowed revenue for pipeline safety expenses	0	[2]
Total Penalty Decision fines and remedies recorded	553,000,000
Penalty Decision Cumulative Charges [Member]
Loss Contingencies [Line Items]
Disallowed capital expenditures	(53,000,000)	[3]
Payment To State General Fund	300,000,000	[4]
Bill Credit to Natural Gas Customers	400,000,000
CPUC Remedial Measures	20,000,000	[1]
Disallowed revenue for pipeline safety expenses	0	[2]
Total Penalty Decision fines and remedies recorded	773,000,000
Penalty Decision Anticipated Future Financial Impact [Member]
Loss Contingencies [Line Items]
Disallowed capital expenditures	(636,000,000)	[3]
Payment To State General Fund	0	[4]
Bill Credit to Natural Gas Customers	0
CPUC Remedial Measures	30,000,000	[1]
Disallowed revenue for pipeline safety expenses	161,000,000	[2]
Total Penalty Decision fines and remedies recorded	827,000,000
Pacific Gas And Electric Company [Member]
Loss Contingencies [Line Items]
Disallowed capital expenditures	(53,000,000)		0
Pacific Gas And Electric Company [Member] | Criminal investigation [Member] | Original Indictment [Member]
Loss Contingencies [Line Items]
Number of felony counts	12
Pacific Gas And Electric Company [Member] | Criminal investigation [Member] | Superceding Indictment [Member]
Loss Contingencies [Line Items]
Statutory penalty for each count of alleged violation	500,000
Total maximum statutory penalties	14,000,000
Number of felony counts	15
Gross Gain Derived From Alleged Violation	281,000,000
Gross Loss Derived From Alleged Violation	565,000,000
Maximum Alternative Fine Sought	1,130,000,000
Pacific Gas And Electric Company [Member] | Criminal investigation [Member] | Alleged obstruction of NTSB's investigation [Member]
Loss Contingencies [Line Items]
Number of felony counts	1
Pacific Gas And Electric Company [Member] | Minimum [Member]
Loss Contingencies [Line Items]
SED fines for self-reported violations	50,000
Fines Imposed in GT&S Rate Case	250,000,000
Pacific Gas And Electric Company [Member] | Maximum [Member]
Loss Contingencies [Line Items]
SED fines for self-reported violations	16,800,000
Fines Imposed in GT&S Rate Case	2,500,000,000
Pacific Gas And Electric Company [Member] | CAISO And PX [Member]
Loss Contingencies [Line Items]
Disputed Claims Liability Balance	434,000,000
Other Receivables Disputed Claims	291,000,000
Pacific Gas And Electric Company [Member] | Ex Parte Communications [Member]
Loss Contingencies [Line Items]
CPUC Imposed Fine	$ 1,050,000

[1] In the Penalty Decision, the CPUC estimates that the Utility would incur $50 million to comply with the other remedies in the Penalty Decision, including $30 million to reimburse the CPUC for the costs of future audits. Remedial costs are expensed as incurred. Other than the refund of CPUC audit costs, the majority of the remedies have been completed or are underway and the associated costs have already been incurred.

[2] These costs are being expensed as incurred. Future GT&S revenues will be reduced for these unrecovered expenses.

[3] The Penalty Decision prohibits the Utility from recovering certain expenses and capital spending associated with pipeline safety-related projects and programs that the CPUC will identify in the final decision to be issued in the Utility’s 2015 GT&S rate case. The Utility estimates that approximately $53 million of capital spending in the three months ended March 31, 2015 is probable of disallowance, subject to adjustment based on the final 2015 GT&S rate case decision.

[4] The Utility increased its accrual from $200 million at December 31, 2014 to $300 million at March 31, 2015.