REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Long-Term Regulatory Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 9,981	$ 9,270
Cost of removal obligations
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	6,902	6,456
Recoveries in excess of AROs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	351	393
Public purpose programs
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	930	817
Employee benefit plans
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	774	750
Other
Regulatory Liabilities [Line Items]
Total long-term regulatory liabilities	$ 1,024	$ 854