Reporting Segments and Related Information - Adjusted EBIT (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Oct. 30, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Adjusted EBIT										$ 1,438	$ 1,515	$ 1,440
Gain on derecognition of subsidiary	$ (177)									(177)	0	0
Restructuring expense		$ 31	$ 14	$ 13	$ 14	$ 23	$ 6	$ 31	$ 8	72	67	58
Unfavorable arbitration loss										14	0	0
Asset impairment and loss on divestiture						26				7	25	71
Asbestos-related adjustments						23				0	23	0
Gain on sale of building						(19)				0	(19)	0
Other postretirement income		1	(1)	27	0	(2)	(3)	(2)	(3)	27	(10)	(5)
Income (Loss) from Equity Method Investments		7	7	9	9	11	15	13	10	32	49	51
Officer stock awards modification										2	8	0
Merger, acquisition and divestiture expense						1	2	1	2	11	6	10
Lease termination settlement										0	0	5
Other (income) expense, net										0	(4)	2
Corporate, including stock-based compensation										206	219	222
Interest income		(3)	(4)	(2)	(3)	(2)	(1)	(1)	(2)	(12)	(6)	(6)
Interest expense		12	15	14	14	14	14	15	16	55	59	71
Earnings before income taxes and noncontrolling interest										1,265	1,196	1,063
Provision for income taxes		238	66	73	91	19	67	30	95	468	211	580
Net earnings		237	207	182	171	248	216	284	237	797	985	483
Net earnings attributable to the noncontrolling interest, net of tax		17	13	10	11	18	12	12	12	51	54	43
Net earnings attributable to BorgWarner Inc.		$ 220	$ 194	$ 172	$ 160	$ 230	$ 204	$ 272	$ 225	746	931	440
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement										(27)	0	0
Engine [Member]
Segment Reporting Information [Line Items]
Adjusted EBIT										995	1,040	992
Drivetrain [Member]
Segment Reporting Information [Line Items]
Adjusted EBIT										$ 443	475	$ 448
Restructuring expense											$ 7