SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Revenues Disaggregated by Type of Customer) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from contracts with customers
Total operating revenues	$ 17,129	$ 16,759	$ 17,135
Electric
Revenue from contracts with customers
Total operating revenues	12,740	12,713	13,124
Natural gas
Revenue from contracts with customers
Total operating revenues	4,389	4,046	4,011
Pacific Gas & Electric Co
Revenue from contracts with customers
Total operating revenues	17,129	16,760	17,138
Pacific Gas & Electric Co | Electric
Revenue from contracts with customers
Total operating revenues	12,437	12,077
Regulatory balancing accounts	303	636
Total operating revenues	12,740	12,713	13,127
Pacific Gas & Electric Co | Electric | Residential
Revenue from contracts with customers
Total operating revenues	4,847	5,051
Pacific Gas & Electric Co | Electric | Commercial
Revenue from contracts with customers
Total operating revenues	4,756	4,908
Pacific Gas & Electric Co | Electric | Industrial
Revenue from contracts with customers
Total operating revenues	1,493	1,532
Pacific Gas & Electric Co | Electric | Agricultural
Revenue from contracts with customers
Total operating revenues	1,106	1,234
Pacific Gas & Electric Co | Electric | Public street and highway lighting
Revenue from contracts with customers
Total operating revenues	67	72
Pacific Gas & Electric Co | Electric | Other
Revenue from contracts with customers
Total operating revenues	168	(720)
Pacific Gas & Electric Co | Natural gas
Revenue from contracts with customers
Total operating revenues	4,302	3,805
Regulatory balancing accounts	87	242
Total operating revenues	4,389	4,047	$ 4,011
Pacific Gas & Electric Co | Natural gas | Residential
Revenue from contracts with customers
Total operating revenues	2,325	2,042
Pacific Gas & Electric Co | Natural gas | Commercial
Revenue from contracts with customers
Total operating revenues	605	537
Pacific Gas & Electric Co | Natural gas | Transportation service only
Revenue from contracts with customers
Total operating revenues	1,249	1,151
Pacific Gas & Electric Co | Natural gas | Other
Revenue from contracts with customers
Total operating revenues	$ 123	$ 75