RESTRUCTURING - Roll forward of the restructuring liability (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		$ 35	$ 31
Delphi Technologies acquisition		75
Restructuring expense, net	$ 50	203	72	$ 67
Cash payments		(135)	(68)
Foreign currency translation adjustment and other		(5)	0
Restructuring reserve, ending balance	35	173	35	31
Less: Non-current restructuring liability		62
Current restructuring liability		111
Employee termination benefits
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		34	25
Delphi Technologies acquisition		73
Restructuring expense, net		157	44
Cash payments		(113)	(35)
Foreign currency translation adjustment and other		9	0
Restructuring reserve, ending balance	34	160	34	25
Less: Non-current restructuring liability		59
Current restructuring liability		101
Other
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		1	6
Delphi Technologies acquisition		2
Restructuring expense, net		46	28
Cash payments		(22)	(33)
Foreign currency translation adjustment and other		(14)	0
Restructuring reserve, ending balance	$ 1	13	$ 1	$ 6
Less: Non-current restructuring liability		3
Current restructuring liability		$ 10