Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Public Utility, Property, Plant and Equipment [Line Items]
Increase in asset retirement obligaiton	$ (66)	$ 92
Income tax provision (benefit)		$ 511	$ 55	$ (27)
Pacific Gas And Electric Company [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Composite depreciation rate		3.83%	3.73%	3.80%
AFUDC interest recorded		$ 38	$ 51	$ 48
AFUDC equity recorded		89	112	107
Nuclear decommissioning obligation accrued		3,500	3,500
Estimated cost recovery on spent nuclear fuel storage proceeding every year		4,100
Approximate estimated nuclear decommissioning cost in future dollars		7,000
Income tax provision (benefit)		$ 427	$ 70	$ (19)