SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Revenues Disaggregated by Type of Customer) (Details) - Pacific Gas & Electric Co - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue from contracts with customers
Total operating revenues	$ 4,432	$ 4,382	$ 12,386	$ 12,672
Electric
Revenue from contracts with customers
Total revenue from contracts with customers	3,935	3,795	8,995	9,519
Regulatory balancing accounts	(381)	(328)	297	211
Total operating revenues	3,554	3,467	9,292	9,730
Electric | Residential
Revenue from contracts with customers
Total revenue from contracts with customers	1,557	1,649	3,839	4,023
Electric | Commercial
Revenue from contracts with customers
Total revenue from contracts with customers	1,481	1,430	3,568	3,737
Electric | Industrial
Revenue from contracts with customers
Total revenue from contracts with customers	466	448	1,085	1,126
Electric | Agricultural
Revenue from contracts with customers
Total revenue from contracts with customers	496	523	844	966
Electric | Public street and highway lighting
Revenue from contracts with customers
Total revenue from contracts with customers	17	18	50	55
Electric | Other
Revenue from contracts with customers
Total revenue from contracts with customers	(82)	(273)	(391)	(388)
Natural gas
Revenue from contracts with customers
Total revenue from contracts with customers	507	646	2,872	2,752
Regulatory balancing accounts	371	269	222	190
Total operating revenues	878	915	3,094	2,942
Natural gas | Residential
Revenue from contracts with customers
Total revenue from contracts with customers	249	242	1,764	1,652
Natural gas | Commercial
Revenue from contracts with customers
Total revenue from contracts with customers	92	87	461	402
Natural gas | Transportation service only
Revenue from contracts with customers
Total revenue from contracts with customers	264	287	950	847
Natural gas | Other
Revenue from contracts with customers
Total revenue from contracts with customers	$ (98)	$ 30	$ (303)	$ (149)