Reporting Segments - Earnings before interest and income taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information
Adjusted EBIT	$ 356	$ 341	$ 656	$ 1,038
Restructuring expense	20	14	72	41
Merger, acquisition and divestiture expense	16	4	58	10
Asset impairments	0	0	26	0
Net gain on insurance recovery for property damage	(3)	0	(9)	0
Unfavorable arbitration loss	0	0	0	14
Officer stock awards modification	0	0	0	2
Corporate, including stock-based compensation	39	47	114	146
Equity in affiliates’ earnings, net of tax	(3)	(7)	(10)	(25)
Interest income	(3)	(4)	(8)	(9)
Interest expense	20	15	50	43
Other postretirement (income) expense	(2)	(1)	(5)	26
Earnings before income taxes and noncontrolling interest	272	273	368	790
Provision for income taxes	143	66	186	230
Net earnings	129	207	182	560
Net earnings attributable to the noncontrolling interest, net of tax	18	13	40	34
Net earnings attributable to BorgWarner Inc.	111	194	142	526
Engine
Segment Reporting Information
Adjusted EBIT	225	241	461	731
Drivetrain
Segment Reporting Information
Adjusted EBIT	$ 131	$ 100	$ 195	$ 307