OTHER CONTINGENCIES AND COMMITMENTS (Order Instituting Investigation Narrative) (Details) $ in Millions	Sep. 30, 2021 USD ($)	Jan. 04, 2021 party	Jun. 08, 2020 party	Apr. 20, 2020 USD ($)	Dec. 17, 2019 USD ($)
Loss Contingencies [Line Items]
Expenses and capital expenditures, disallowed costs	$ 1,625
Expenses and capital expenditures, disallowed capital, approved				$ 198
Shareholder-funded system enhancement initiatives, approved				64
Fine payable to general fund, suspended				$ 200
Number of parties filed separate applications for rehearing (party) | party			2
Number of parties filed petition for review of decision (party) | party		1
Pacific Gas & Electric Co (Utility)
Loss Contingencies [Line Items]
Expenses and capital expenditures	$ 1,625
Pacific Gas & Electric Co (Utility) | Pending Litigation | Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Expenses and capital expenditures					$ 1,625
Shareholder-funded system enhancement initiatives, amount					$ 50