REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Long-Term Regulatory Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 9,038	$ 8,539
Cost of removal obligations
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	6,233	5,981
Deferred income taxes
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	4	283
Recoveries in excess of AROs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	472	356
Public purpose programs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	785	674
Employee benefit plans
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	423	421
Other
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 1,121	$ 824