REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Current Regulatory Balancing Accounts, Net) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Total regulatory balancing accounts payable
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	$ 1,139	$ 1,245
Total regulatory balancing accounts payable | Electric distribution
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	330	55
Total regulatory balancing accounts payable | Electric transmission
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	100	267
Total regulatory balancing accounts payable | Gas distribution and transmission
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	53	76
Total regulatory balancing accounts payable | Energy procurement
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	133	158
Total regulatory balancing accounts payable | Public purpose programs
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	300	410
Total regulatory balancing accounts payable | Other
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	223	279
Total regulatory balancing accounts receivable
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	2,905	2,001
Total regulatory balancing accounts receivable | Gas distribution and transmission
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	225	102
Total regulatory balancing accounts receivable | Energy procurement
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	225	413
Total regulatory balancing accounts receivable | Public purpose programs
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	278	292
Total regulatory balancing accounts receivable | Fire hazard prevention memorandum account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	81	121
Total regulatory balancing accounts receivable | Fire risk mitigation memorandum account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	22	33
Total regulatory balancing accounts receivable | Wildfire mitigation plan memorandum account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	108	161
Total regulatory balancing accounts receivable | Wildfire mitigation balancing account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	41	27
Total regulatory balancing accounts receivable | General rate case memorandum accounts
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	467	313
Total regulatory balancing accounts receivable | Vegetation management balancing account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	277	115
Total regulatory balancing accounts receivable | Insurance premium costs
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	508	135
Total regulatory balancing accounts receivable | Other
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	$ 673	$ 289