REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Long-Term Regulatory Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Total long-term regulatory assets	$ 7,507	$ 6,066
Retained generation asset costs	1,200
Pension benefits
Regulatory Assets [Line Items]
Total long-term regulatory assets	1,757	1,823
Environmental compliance costs
Regulatory Assets [Line Items]
Total long-term regulatory assets	1,082	1,062
Utility retained generation
Regulatory Assets [Line Items]
Total long-term regulatory assets	205	228
Price risk management
Regulatory Assets [Line Items]
Total long-term regulatory assets	183	124
Unamortized loss, net of gain, on reacquired debt
Regulatory Assets [Line Items]
Total long-term regulatory assets	56	63
Catastrophic event memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	646	656
Wildfire expense memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	423	423
Fire hazard prevention memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	261	259
Fire risk mitigation memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	98	95
Wild fire mitigation plan memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	993	558
Deferred income taxes
Regulatory Assets [Line Items]
Total long-term regulatory assets	583	252
Insurance premium costs
Regulatory Assets [Line Items]
Total long-term regulatory assets	481	0
Other
Regulatory Assets [Line Items]
Total long-term regulatory assets	$ 739	$ 523