ACCUMULATED OTHER COMPREHENSIVE LOSS - Accumulated Other Comprehensive Income Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance	$ 703	$ 2,225	$ 3,582
Other comprehensive (loss) income before reclassifications	236	37	(387)
Reclassification adjustments	(10)	(7)	17
Total other comprehensive income (loss), net of tax	226	30	$ (370)
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201601Member
Ending balance	430	703	$ 2,225
Intra-entity foreign currency long-term-investment gains (losses)	(44)	6	14
Foreign Currency Translation Adjustments
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance	(368)	(403)	(23)
Other comprehensive (loss) income before reclassifications	229	35	(391)
Reclassification adjustments	0	0	11
Total other comprehensive income (loss), net of tax	229	35	(380)
Ending balance	(139)	(368)	(403)
Derivative Instrument and Other Adjustments
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance	7	12	6
Other comprehensive (loss) income before reclassifications	7	2	4
Reclassification adjustments	(10)	(7)	6
Total other comprehensive income (loss), net of tax	(3)	(5)	10
Ending balance	4	7	12
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance	(361)	(391)	(17)
Total other comprehensive income (loss), net of tax	226	30	(370)
Ending balance	$ (135)	$ (361)	(391)
Accounting Standards Update 2016-01 | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance			0
Accounting Standards Update 2016-01 | Foreign Currency Translation Adjustments | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance			0
Accounting Standards Update 2016-01 | Derivative Instrument and Other Adjustments | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance			(4)
Accounting Standards Update 2016-01 | Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent [Roll forward] [Abstract]
Beginning balance			$ (4)