CONSOLIDATED DEBT Revolving Credit Facility (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 577	$ 636
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,000
Long-term Line of Credit	387	$ 445
Letters of Credit Outstanding, Amount	212
Line of Credit Facility, Remaining Borrowing Capacity	401
Revolving Credit Facility Tranche A [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	950
Revolving Credit Facility Tranche B [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 50