OTHER CONTINGENCIES AND COMMITMENTS (Purchase and Commitment Agreements) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Nuclear Fuel
Third-Party Power Purchase Agreements [Line Items]
Payments for nuclear fuel	$ 73	$ 83	$ 100
Qualifying Facilities
Third-Party Power Purchase Agreements [Line Items]
Capitalized asset for fixed capacity payments for corresponding assets	11	18
Capitalized asset for fixed capacity payments, accumulated amortization	8	143
Present value of fixed capacity payments, portion classified as current liabilities	2	11
Present value of fixed capacity payments, portion classified as noncurrent liabilities	9	7
Power Purchases and Electric Capacity
Third-Party Power Purchase Agreements [Line Items]
Costs incurred for power purchases and electric capacity	3,100	3,300	3,500
Gas Contracts
Third-Party Power Purchase Agreements [Line Items]
Cost of goods	$ 600	$ 900	$ 700