REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Long-Term Regulatory Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 9,336	$ 8,539
Cost of removal obligations
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	6,341	5,981
Deferred income taxes
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	462	356
Public purpose programs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	802	674
Employee benefit plans
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	428	421
Other
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 1,303	$ 824