OTHER CONTINGENCIES AND COMMITMENTS (Third-Party Power Purchase Agreements and Other Agreements) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Power Purchases and Electric Capacity
Third-Party Power Purchase Agreements [Line Items]
Costs incurred for power purchases and electric capacity	$ 2,900	$ 3,000	$ 3,100
Nuclear Fuel
Third-Party Power Purchase Agreements [Line Items]
Payments for nuclear fuel	111	74	73
Gas Contracts
Third-Party Power Purchase Agreements [Line Items]
Cost of goods	$ 800	$ 900	$ 600