SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) facility	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Period for probable revenue recovery	24 months
Operating lease right of use asset	$ 2,286
Operating lease, right-of-use liability	2,279
Operating lease, payments	$ 2,400
Weighted average remaining lease term	5 years 10 months 24 days
Weighted average discount rate	6.20%
Accounting Standards Update 2016-02
Public Utility, Property, Plant and Equipment [Line Items]
Operating lease right of use asset				$ 2,800
Operating lease, right-of-use liability				$ 2,800
Pacific Gas & Electric Co
Public Utility, Property, Plant and Equipment [Line Items]
Composite depreciation rate	3.80%	3.82%	3.83%
AFUDC debt recorded	$ 55	$ 53	$ 38
AFUDC equity recorded	79	129	$ 89
Nuclear decommissioning obligation accrued	4,900	4,700
Estimated cost recovery on spent nuclear fuel storage proceeding every year	10,600	$ 10,600
Operating lease right of use asset	$ 2,279
Pacific Gas & Electric Co | Diablo Canyon
Public Utility, Property, Plant and Equipment [Line Items]
Number of generation facilities | facility	2
Pacific Gas & Electric Co | Humboldt Bay
Public Utility, Property, Plant and Equipment [Line Items]
Number of generation facilities | facility	1