REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Long-Term Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 9,270	$ 8,539
Cost of removal obligations
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	6,456	5,981
Deferred income tax
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	0	283
Recoveries in excess of AROs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	393	356
Public purpose programs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	817	674
Retirement Plan
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	750	421
Other
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 854	$ 824