REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Current Regulatory Balancing Accounts, Net) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Regulatory Liabilities [Line Items]
Regulatory balancing accounts	$ 410	$ 315
Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	1,245	1,797
Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	2,001	2,114
Electric distribution | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	55	31
Electric transmission | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	267	119
Electric transmission | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	0	9
Gas distribution and transmission | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	76	45
Gas distribution and transmission | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	102	363
Energy procurement | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	158	649
Energy procurement | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	413	901
Public purpose programs | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	410	559
Public purpose programs | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	292	209
Fire hazard prevention memorandum account | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	121	0
Fire risk mitigation memorandum account | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	33	0
Wildfire mitigation plan memorandum account | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	161	0
Wildfire mitigation balancing account | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	27	0
General rate case memorandum accounts | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	313	0
Vegetation management balancing account | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	115	0
Insurance premium costs
Regulatory Liabilities [Line Items]
Regulatory balancing accounts	93
Insurance premium costs | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	135	0
Other | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	279	394
Other | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	$ 289	$ 632