REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Current Regulatory Balancing Accounts, Net) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Total regulatory balancing accounts payable
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	$ 1,368	$ 1,245
Total regulatory balancing accounts payable | Electric distribution
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	0	55
Total regulatory balancing accounts payable | Electric transmission
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	260	267
Total regulatory balancing accounts payable | Gas distribution and transmission
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	280	76
Total regulatory balancing accounts payable | Energy procurement
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	116	158
Total regulatory balancing accounts payable | Public purpose programs
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	372	410
Total regulatory balancing accounts payable | Other
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	340	279
Total regulatory balancing accounts receivable
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	2,249	2,001
Total regulatory balancing accounts receivable | Electric distribution
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	266	0
Total regulatory balancing accounts receivable | Gas distribution and transmission
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	3	102
Total regulatory balancing accounts receivable | Energy procurement
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	346	413
Total regulatory balancing accounts receivable | Public purpose programs
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	309	292
Total regulatory balancing accounts receivable | Fire hazard prevention memorandum account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	121	121
Total regulatory balancing accounts receivable | Fire risk mitigation memorandum account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	33	33
Total regulatory balancing accounts receivable | Wildfire mitigation plan memorandum account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	161	161
Total regulatory balancing accounts receivable | Wildfire mitigation balancing account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	29	27
Total regulatory balancing accounts receivable | General rate case memorandum accounts
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	468	313
Total regulatory balancing accounts receivable | Vegetation management balancing account
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	49	115
Total regulatory balancing accounts receivable | Insurance premium costs
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	157	135
Total regulatory balancing accounts receivable | Other
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	$ 307	$ 289