Reporting Segments and Related Information - Adjusted EBIT (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Adjusted EBIT									$ 1,195.3	$ 1,227.3	$ 1,078.2
Restructuring expense	$ 24.4	$ 6.3	$ 10.5	$ 9.4	$ 17.8	$ 9.6	$ 13.0	$ 38.4	65.7	90.8	39.8
Intangible asset impairment									0.0	10.3	12.5
Pension settlement									25.7	3.1	0.0
Merger and acquisition expense	17.9	3.9							21.8	0.0	0.0
Gain on previously held equity interest									(10.8)	0.0	0.0
Program termination agreement										0.0	11.3
Retirement related obligations											5.9
Corporate, including equity in affiliates' earnings and stock-based compensation									113.2	112.1	110.0
Interest income	(2.2)	(2.0)	(1.6)	(1.7)	(1.2)	(1.4)	(1.4)	(1.5)	(7.5)	(5.5)	(4.8)
Interest expense and finance charges	17.8	15.0	17.6	10.0	10.2	9.0	9.0	8.2	60.4	36.4	34.2
Earnings before income taxes and noncontrolling interest									926.8	980.1	869.3
Provision for income taxes	61.2	66.9	80.2	72.1	67.3	71.9	85.3	68.1	280.4	292.6	218.3
Net earnings	135.4	165.9	157.4	187.7	147.4	173.0	199.9	167.2	646.4	687.5	651.0
Net earnings attributable to the noncontrolling interest, net of tax	10.1	8.5	9.3	8.8	7.5	6.4	9.7	8.1	36.7	31.7	26.7
Net earnings attributable to BorgWarner Inc.	125.3	157.4	148.1	178.9	139.9	166.6	190.2	159.1	609.7	655.8	624.3
Tax benefit associated with restructuring	$ 0.4	$ 0.7	$ 2.2	$ 1.2	3.4	1.4	$ 1.7	$ 8.8	3.7	15.3	5.1
Engine [Member]
Segment Reporting Information [Line Items]
Adjusted EBIT									900.7	924.0	826.0
Drivetrain [Member]
Segment Reporting Information [Line Items]
Adjusted EBIT									294.6	303.3	252.2
U.S. Plans:
Segment Reporting Information [Line Items]
Pension settlement					$ 0.4	$ 2.7			$ 25.7	$ 3.1	$ 0.0