SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Wildfire Fund) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) contribution	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) contribution	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Jul. 12, 2019 USD ($)
Loss Contingencies [Line Items]
Expected capitalization, proceeds of bond	$ 10,500		$ 10,500			$ 10,500
Expected capitalization, initial contribution	7,500		7,500			7,500
Expected capitalization, annual contribution	$ 300		$ 300			$ 300
Expected wildfire fund allocation metric, percentage	64.20%		64.20%
Expected wildfire fund allocation metric, initial contribution	$ 4,800		$ 4,800
Expected wildfire fund allocation metric, annual contributions	193		193
Initial contribution payment	4,800		4,800
Annual contribution, first payment	193		193
Annual contribution, second payment	$ 193		$ 193
Number of remaining annual contributions | contribution	8		8
Wildfire fund, current asset	$ 461		$ 461		$ 464
Wildfire fund, noncurrent asset	5,428		5,428		5,816
Wildfire Fund expense	$ 162	$ 120	$ 399	$ 293
Monte carlo simulation, historical data, period			12 years
Amortization period			6 years
Percentage assumption change	10.00%		10.00%
Greater effectiveness, amortization period			17 years
Less effectiveness, amortization period			12 years
Litigation Settlement, Expense
Loss Contingencies [Line Items]
Accelerated amortization			$ 42
Pacific Gas & Electric Co (Utility)
Loss Contingencies [Line Items]
Wildfire fund, current asset	$ 461		461		464
Wildfire fund, noncurrent asset	5,428		5,428		$ 5,816
Wildfire Fund expense	162	$ 120	$ 399	$ 293
5 year period
Loss Contingencies [Line Items]
Historical data period			5 years
Average annual statewide claims or settlements	6,500		$ 6,500
12 year period
Loss Contingencies [Line Items]
Historical data period			12 years
Average annual statewide claims or settlements	2,900		$ 2,900
Wildfire Fund asset
Loss Contingencies [Line Items]
Finite-lived intangible asset, useful life			15 years
Current liabilities - other
Loss Contingencies [Line Items]
Litigation liability, current	193		$ 193
Noncurrent liabilities – other
Loss Contingencies [Line Items]
Wildfire fund, noncurrent	1,300		1,300
Noncurrent assets – other
Loss Contingencies [Line Items]
Wildfire fund receivables	$ 150		$ 150