SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Revenues Disaggregated by Type of Customer) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accounting Policies [Abstract]
Period for probable revenue recovery			24 months
Pacific Gas & Electric Co (Utility)
Revenue from contracts with customers
Total operating revenues	$ 5,465	$ 4,882	$ 15,396	$ 13,721
Pacific Gas & Electric Co (Utility) | Electric
Revenue from contracts with customers
Total revenue from contracts with customers	4,630	4,296	11,113	10,018
Regulatory balancing accounts	(449)	(486)	414	267
Total operating revenues	4,181	3,810	11,527	10,285
Pacific Gas & Electric Co (Utility) | Electric | Residential
Revenue from contracts with customers
Total revenue from contracts with customers	1,962	1,862	4,778	4,092
Pacific Gas & Electric Co (Utility) | Electric | Commercial
Revenue from contracts with customers
Total revenue from contracts with customers	1,580	1,455	3,776	3,537
Pacific Gas & Electric Co (Utility) | Electric | Industrial
Revenue from contracts with customers
Total revenue from contracts with customers	467	453	1,099	1,135
Pacific Gas & Electric Co (Utility) | Electric | Agricultural
Revenue from contracts with customers
Total revenue from contracts with customers	655	657	1,238	1,149
Pacific Gas & Electric Co (Utility) | Electric | Public street and highway lighting
Revenue from contracts with customers
Total revenue from contracts with customers	18	17	53	51
Pacific Gas & Electric Co (Utility) | Electric | Other
Revenue from contracts with customers
Total revenue from contracts with customers	(52)	(148)	169	54
Pacific Gas & Electric Co (Utility) | Natural gas
Revenue from contracts with customers
Total revenue from contracts with customers	736	679	3,234	2,978
Regulatory balancing accounts	548	393	635	458
Total operating revenues	1,284	1,072	3,869	3,436
Pacific Gas & Electric Co (Utility) | Natural gas | Residential
Revenue from contracts with customers
Total revenue from contracts with customers	295	303	1,921	1,795
Pacific Gas & Electric Co (Utility) | Natural gas | Commercial
Revenue from contracts with customers
Total revenue from contracts with customers	102	90	486	434
Pacific Gas & Electric Co (Utility) | Natural gas | Transportation service only
Revenue from contracts with customers
Total revenue from contracts with customers	323	259	995	902
Pacific Gas & Electric Co (Utility) | Natural gas | Other
Revenue from contracts with customers
Total revenue from contracts with customers	$ 16	$ 27	$ (168)	$ (153)