INCOME TAXES (Schedule of Change in Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pacific Gas & Electric Co (Utility)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, beginning of period	$ 420	$ 377	$ 349
Reductions for tax position taken during a prior year	(43)	(1)	(27)
Additions for tax position taken during the current year	60	44	55
Settlements	0	0	0
Expiration of statute	0	0	0
Balance, end of period	437	420	377
PG&E Corporation
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, beginning of period	420	377	349
Reductions for tax position taken during a prior year	(43)	(1)	(27)
Additions for tax position taken during the current year	60	44	55
Settlements	0	0	0
Expiration of statute	0	0	0
Balance, end of period	$ 437	$ 420	$ 377