Regulatory Assets, Liabilities, And Balancing Accounts (Long-Term Regulatory Assets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Regulatory Assets [Line Items]
Total long-term regulatory assets		$ 3,793		$ 7,951
Weighted average remaining life of Utility retained generation assets (years)		9 years
Environmental compliance costs regulatory asset recovery (years)		32 years
Price risk management regulatory assets recovery (years)		10 years
Recovery of costs related to debt reacquired or redeemed prior to maturity (years)		25 years
Retained Generation Asset Costs		$ 1,200
Pension benefits regulatory assets recovery (years)	[1]	Indefinitely
Other regulatory assets recovery (years)		Various
Current regulatory assets		$ 615		423
Pension Plans Defined Benefit [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets	[2],[3]	1,954		2,429
Deferred Income Taxes [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets	[3]	0	[4]	3,859
Utility Retained Generation [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets	[5]	319		364
Environmental Compliance Costs [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets	[3]	837		778
Price Risk Management [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets	[3]	65		92
Unamortized Loss, Net Of Gain, On Reacquired Debt [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets	[3]	79		76
Other Regulatory Assets ( Liabilities) [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets		539		353
Catastrophic Event Memorandum Account [Member]
Regulatory Assets [Line Items]
Total long-term regulatory assets		274		70
Current regulatory assets		$ 426		$ 223

[1] Payments into the pension and other benefits plans are based on annual contribution requirements. As these annual requirements continue indefinitely into the future, the Utility expects to continuously recover pension benefits.

[2] Payments into the pension and other benefits plans are based on annual contribution requirements. As these annual requirements continue indefinitely into the future, the Utility expects to continuously recover pension benefits.

[3] Represents the cumulative differences between amounts recognized for ratemaking purposes and expense or accumulated other comprehensive income (loss) recognized in accordance with GAAP.

[4] The change in the balance from a regulatory asset as of December 31, 2016 to a regulatory liability as of December 31, 2017 reflects the impact of changes in net deferred tax liabilities associated with a lower federal income tax rate as a result of the Tax Act. (See “Regulatory Liabilities” below and Note 8.)

[5] In connection with the settlement agreement entered into among PG&E Corporation, the Utility, and the CPUC in 2003 to resolve the Utility’s proceeding under Chapter 11, the CPUC authorized the Utility to recover $1.2 billion of costs related to the Utility’s retained generation assets. The individual components of these regulatory assets are being amortized over the respective lives of the underlying generation facilities, consistent with the period over which the related revenues are recognized.