OTHER CONTINGENCIES AND COMMITMENTS (Other Commitments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Payments for operating leases	$ 48	$ 43	$ 45
Operating Leased Assets [Line Items]
Present value of fixed capacity payments, portion classified as current liabilities	556
Present value of fixed capacity payments, portion classified as noncurrent liabilities	1,730
Qualifying Facilities
Operating Leased Assets [Line Items]
Capitalized asset for fixed capacity payments for corresponding assets	9	11
Capitalized asset for fixed capacity payments, accumulated amortization	9	8
Present value of fixed capacity payments, portion classified as current liabilities	2	2
Present value of fixed capacity payments, portion classified as noncurrent liabilities	$ 7	$ 9
Minimum
Operating Leased Assets [Line Items]
Extension option for operating leases	1 year
Maximum
Operating Leased Assets [Line Items]
Extension option for operating leases	5 years