DERIVATIVES (Outstanding Derivative Balances) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivatives And Hedging Activities [Line Items]
Gross Derivative Balance		$ 8
Netting	$ (115)
Netting	25	14
Commodity Contract | Pacific Gas & Electric Co (Utility)
Derivatives And Hedging Activities [Line Items]
Gross Derivative Balance	(73)	5
Netting	0	0
Cash Collateral	140	6
Total Derivative Balance	67	11
Commodity Contract | Pacific Gas & Electric Co (Utility) | Current assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Balance	33	36
Netting	0	(6)
Cash Collateral	115	4
Total Derivative Balance	148	34
Commodity Contract | Pacific Gas & Electric Co (Utility) | Other noncurrent assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Balance	136	130
Netting	0	(6)
Cash Collateral	0	0
Total Derivative Balance	136	124
Commodity Contract | Pacific Gas & Electric Co (Utility) | Current liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Balance	(38)	(31)
Netting	0	6
Cash Collateral	15	2
Total Derivative Balance	(23)	(23)
Commodity Contract | Pacific Gas & Electric Co (Utility) | Noncurrent liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Balance	(204)	(130)
Netting	0	6
Cash Collateral	10	0
Total Derivative Balance	$ (194)	$ (124)