CONTINGENCIES AND COMMITMENTS (Tax Matters) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Unrecognized tax benefits, decrease resulting from Settlements with taxing authorities	$ 20
Pacific Gas & Electric Co | Forecast | Rate Case 2015, 2017, 2019
Disaggregation Of Revenue [Line Items]
Reduction in revenue requirement			$ 325
Increase to rate base		$ 613	271
Pacific Gas & Electric Co | Forecast | Other Rate Cases, Including TO19
Disaggregation Of Revenue [Line Items]
Reduction in revenue requirement			125
Increase to rate base		$ 200	$ 100