CONTINGENCIES AND COMMITMENTS (Summary of Estimated Losses Related to Wildfire-Related Claims) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Loss Contingencies [Line Items]
Total wildfire-related claims, net of insurance recoveries	$ (10)		$ 53	$ 2,108	$ 0
Nothern California Wild Fire
Loss Contingencies [Line Items]
Third-Party Claims		$ 2,500
Pacific Gas & Electric Co
Loss Contingencies [Line Items]
Total wildfire-related claims, net of insurance recoveries	(10)		53	2,108	0
Pacific Gas & Electric Co | Butte Fire
Loss Contingencies [Line Items]
Third-Party Claims	0		350	0	350
Insurance recoveries	0		(297)	(7)	(350)
Total wildfire-related claims, net of insurance recoveries	0		53	(7)	0
Pacific Gas & Electric Co | Nothern California Wild Fire
Loss Contingencies [Line Items]
Third-Party Claims	0		0	2,500	0
Insurance recoveries	(10)		0	(385)	0
Total wildfire-related claims, net of insurance recoveries	$ (10)		$ 0	$ 2,115	$ 0