Reporting Segments - Earnings before interest and income taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information
Adjusted EBIT	$ 29	$ 351	$ 300	$ 697
Restructuring expense	37	13	52	27
Merger, acquisition and divestiture expense	21	5	42	6
Asset impairments	17	0	26	0
Net gain on insurance proceeds for property damage	(6)	0	(6)	0
Unfavorable arbitration loss	0	0	0	14
Officer stock awards modification	0	0	0	2
Corporate, including stock-based compensation	38	48	75	99
Equity in affiliates’ earnings, net of tax	(2)	(9)	(7)	(18)
Interest income	(3)	(2)	(5)	(5)
Interest expense	18	14	30	28
Other postretirement (income) expense	(1)	27	(3)	27
(Loss) earnings before income taxes and noncontrolling interest	(90)	255	96	517
(Benefit) provision for income taxes	(6)	73	43	164
Net (loss) earnings	(84)	182	53	353
Net earnings attributable to the noncontrolling interest, net of tax	14	10	22	21
Net (loss) earnings attributable to BorgWarner Inc.	(98)	172	31	332
Engine
Segment Reporting Information
Adjusted EBIT	28	249	236	490
Drivetrain
Segment Reporting Information
Adjusted EBIT	$ 1	$ 102	$ 64	$ 207