BUSINESS SEGMENTS - Segment Profits (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits	$ (128)	$ 252	$ (154)	$ 114	$ 274	$ 607	$ 409	$ 510	$ 84	$ 1,800	$ 2,366
Interest expense, net of interest income									(418)	(368)	(318)
Benefit (provision) for income taxes									199	(326)	(438)
NET (LOSS) INCOME	$ (164)	$ 100	$ (234)	$ 31	$ 279	$ 387	$ 232	$ 375	(267)	1,273	1,907
International Operations | Reimbursements
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									(62)	(18)	(14)
Total segment | International Operations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									(198)	982	1,155
Total segment | U.S. & Canada
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									198	2,000	1,939
Total segment | U.S. & Canada | Reimbursements
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									(80)	(129)	(121)
Total segment | Asia Pacific
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									1	369	456
Total segment | Asia Pacific | Reimbursements
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									(18)	(9)	0
Total segment | EMEA
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									(200)	318	328
Total segment | EMEA | Reimbursements
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									(33)	(8)	0
Unallocated corporate and other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segments profits									$ (47)	$ (720)	$ (60)