LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Debt Issuance Costs, Net	$ (14)	$ (14)		$ (15)
Total	2,312	2,312		2,569
Less current portion	314	314		307
Long-term debt, less current portion	$ 1,998	$ 1,998		$ 2,262
Weighted-average fixed-interest rate	4.10%	4.10%		4.20%
Weighted-average variable-interest rate	3.50%	3.50%		2.80%
Long-term debt payments		$ 258	$ 159
Repayments of Debt	$ 43
Fixed rate notes payable due through 2028 [Member]
Debt Instrument [Line Items]
Total	841	841		$ 959
Variable rate notes payable due through 2028 [Member]
Debt Instrument [Line Items]
Total	$ 1,485	$ 1,485		$ 1,625