LONG-TERM DEBT - SCHEDULE OF LONG-TERM DEBT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term Debt	$ 1,499	$ 2,103
Less debt issuance costs	(8)	(12)
Less current portion	235	486
Long-term debt, net of current portion	$ 1,264	$ 1,617
Weighted-average fixed-interest rate	3.30%	4.10%
Weighted-average variable-interest rate	2.90%	3.90%
Proceeds from issuance of long-term debt, net of issuance costs	$ 450	$ 339	$ 0
Long-term debt payments	1,058	807	$ 397
Repayments of debt	779
Long-term Debt, Fiscal Year Maturity [Abstract]
2020	235
2021	281
2022	243
2023	173
2024	153
Thereafter	420
Long-term Debt	1,505
Fixed-rate notes payable due through 2029
Debt Instrument [Line Items]
Long-term Debt	475	642
Variable-rate notes payable due through 2029
Debt Instrument [Line Items]
Long-term Debt	$ 1,032	$ 1,473