Commitments And Contingencies (Gas Supply, Transportation And Storage) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pacific Gas And Electric Company [Member]
Long-term Purchase Commitment [Line Items]
Cost of natural gas purchases	$ 900	$ 700	$ 900
Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Long Term Contract For Purchase Commitments Expiration Beginning Date	2018
Long Term Contract For Purchase Commitments Expiration Ending Date	2026