SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Wildfire Fund) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) contribution	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Jul. 12, 2019 USD ($)
Loss Contingencies [Line Items]
Expected capitalization, proceeds of bond	$ 10,500			$ 10,500
Expected capitalization, initial contribution	7,500			7,500
Expected capitalization, annual contribution	$ 300			$ 300
Expected wildfire fund allocation metric, percentage	64.20%
Expected wildfire fund allocation metric, initial contribution	$ 4,800
Expected wildfire fund allocation metric, annual contributions	193
Initial contribution payment	4,800
Annual contribution, first payment	193
Annual contribution, second payment	$ 193
Number of remaining annual contributions | contribution	8
Litgation liability, current	$ 193
Wildfire fund, current asset	464		$ 464
Wildfire fund, noncurrent asset	5,700		5,816
Wildfire Fund expense	$ 119	$ 0
Monte carlo simulation, historical data, period	12 years
Amortization period	6 years
Percentage assumption change	10.00%
Greater effectiveness, amortization period	17 years
Less effectiveness, amortization period	12 years
Pacific Gas & Electric Co (Utility)
Loss Contingencies [Line Items]
Wildfire fund, current asset	$ 464		464
Wildfire fund, noncurrent asset	5,700		$ 5,816
Wildfire Fund expense	$ 119	$ 0
5 year period
Loss Contingencies [Line Items]
Historical data period	5 years
Average annual statewide claims or settlements	$ 6,500
12 year period
Loss Contingencies [Line Items]
Historical data period	12 years
Average annual statewide claims or settlements	$ 2,900
Wildfire Fund asset
Loss Contingencies [Line Items]
Finite-lived intangible asset, useful life	15 years
Noncurrent liabilities – other
Loss Contingencies [Line Items]
Wildfire fund, noncurrent	$ 1,300