SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) facility	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2019 USD ($)	Jan. 01, 2016 USD ($)	Dec. 31, 2015 USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Period for probable revenue recovery		24 months
Increase in net cash used in investing activities		$ 6,564	$ 5,650	$ 5,753
Increase in cash, cash equivalents, and restricted cash	$ 1,675	1,675	456	184			$ 357
Increase in operating and maintenance expense		$ 7,153	6,321	7,326
Accounting Standards Update 2016-18
Public Utility, Property, Plant and Equipment [Line Items]
Increase in net cash used in investing activities				227
Increase in cash, cash equivalents, and restricted cash				7		$ 234
Accounting Standards Update 2017-07
Public Utility, Property, Plant and Equipment [Line Items]
Increase in operating and maintenance expense			$ 51	$ 97
Pacific Gas & Electric Co
Public Utility, Property, Plant and Equipment [Line Items]
Composite depreciation rate		3.82%	3.83%	3.73%
AFUDC interest recorded		$ 53	$ 38	$ 51
AFUDC equity recorded		129	89	112
Adjustment to asset retirement obligation	1,100
Nuclear decommissioning obligation accrued		4,700	3,500
Estimated cost recovery on spent nuclear fuel storage proceeding every year			7,000
Approximate estimated nuclear decommissioning cost in future dollars		10,600	7,000
Increase in net cash used in investing activities		6,564	5,650	5,753
Increase in cash, cash equivalents, and restricted cash	$ 1,302	1,302	454	78			$ 293
Increase in operating and maintenance expense		$ 7,153	6,383	7,327
Pacific Gas & Electric Co | Accounting Standards Update 2017-07
Public Utility, Property, Plant and Equipment [Line Items]
Increase in operating and maintenance expense			$ 54	$ 100
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
Minimum | Accounting Standards Update 2016-02 | Scenario, Forecast
Public Utility, Property, Plant and Equipment [Line Items]
Operating lease, right-of-use asset					$ 2,500
Operating lease, right-of-use liability					2,500
Maximum | Accounting Standards Update 2016-02 | Scenario, Forecast
Public Utility, Property, Plant and Equipment [Line Items]
Operating lease, right-of-use asset					3,000
Operating lease, right-of-use liability					$ 3,000