REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Long-Term Regulatory Liabilities) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 11,218	$ 10,424
Proceeds received from sale of transmission tower wireless licenses, refunded to customers	451
Federal Energy Regulatory Commission (FERC)
Regulatory Liabilities [Line Items]
Proceeds received from sale of transmission tower wireless licenses, refunded to customers	315
California Public Utilities Commission (CPUC)
Regulatory Liabilities [Line Items]
Proceeds received from sale of transmission tower wireless licenses, refunded to customers	136
Cost of removal obligations
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	7,139	6,905
Recoveries in excess of AROs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	496	458
Public purpose programs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	914	948
Employee benefit plans
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	1,008	995
Tower Licenses
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	451	0
Other
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 1,210	$ 1,118