REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Long-Term Regulatory Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Regulatory Assets [Line Items]
Total long-term regulatory assets	$ 5,349	$ 4,964
Retained generation asset costs	1,200
Pension benefits
Regulatory Assets [Line Items]
Total long-term regulatory assets	1,928	1,947
Environmental compliance costs
Regulatory Assets [Line Items]
Total long-term regulatory assets	997	1,013
Utility retained generation
Regulatory Assets [Line Items]
Total long-term regulatory assets	251	274
Price risk management
Regulatory Assets [Line Items]
Total long-term regulatory assets	67	90
Unamortized loss, net of gain, on reacquired debt
Regulatory Assets [Line Items]
Total long-term regulatory assets	230	76
Catastrophic event memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	918	790
Wildfire expense memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	127	94
Fire hazard prevention memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	291	263
Fire risk mitigation memorandum account
Regulatory Assets [Line Items]
Total long-term regulatory assets	154	0
Other
Regulatory Assets [Line Items]
Total long-term regulatory assets	$ 386	$ 417