Interim Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 2,586.4	$ 2,416.2	$ 2,389.7	$ 2,407.0	$ 2,259.0	$ 2,214.2	$ 2,329.2	$ 2,268.6	$ 9,799.3		$ 9,071.0		$ 8,023.2
Cost of sales	2,020.5	1,893.5	1,875.5	1,889.7	1,758.0	1,743.1	1,832.5	1,804.3	7,679.2		7,137.9		6,320.1
Gross profit	565.9	522.7	514.2	517.3	501.0	471.1	496.7	464.3	2,120.1		1,933.1		1,703.1
Selling, general and administrative expenses	239.9	224.8	215.0	218.8	217.1	209.7	202.3	188.4	898.5		817.5		662.0
Other expense, net	(117.0)	(22.0)	0.3	(5.8)	(741.9)	(111.1)	(25.0)	(11.7)	144.5		889.7		101.4
Operating income (loss)	209.0	275.9	299.5	292.7	(458.0)	150.3	269.4	264.2	1,077.1		225.9		939.7
Equity in affiliates’ earnings, net of tax	12.7	14.4	14.4	9.7	11.3	12.4	10.1	9.1	(51.2)		(42.9)		(40.0)
Interest income	(1.6)	(1.3)	(1.4)	(1.5)	(1.6)	(1.6)	(1.5)	(1.6)	(5.8)		(6.3)		(7.5)
Interest expense and finance charges	16.9	17.6	18.0	18.0	19.5	22.4	21.4	21.3	70.5		84.6		60.4
Earnings (loss) before income taxes and noncontrolling interest	206.4	274.0	297.3	285.9	(464.6)	141.9	259.6	253.6	1,063.6		190.5		926.8
Provision for income taxes	338.4	79.4	76.2	86.3	(183.1)	48.8	84.2	80.4	580.3		30.3		280.4
Net earnings (loss)	(132.0)	194.6	221.1	199.6	(281.5)	93.1	175.4	173.2	483.3		160.2		646.4
Net earnings attributable to the noncontrolling interest, net of tax	14.2	9.7	9.1	10.4	11.8	9.8	11.0	9.1	43.4	[1]	41.7	[1]	36.7	[1]
Net earnings attributable to BorgWarner Inc.	$ (146.2)	$ 184.9	$ 212.0	$ 189.2	$ (293.3)	$ 83.3	$ 164.4	$ 164.1	$ 439.9		$ 118.5		$ 609.7
Earnings per share — basic	$ (0.70)	$ 0.88	$ 1.01	$ 0.89	$ (1.39)	$ 0.39	$ 0.76	$ 0.75	$ 2.09		$ 0.55		$ 2.72
Earnings per share — diluted	$ (0.70)	$ 0.88	$ 1.00	$ 0.89	$ (1.39)	$ 0.39	$ 0.76	$ 0.75	$ 2.08		$ 0.55		$ 2.70
Restructuring expense	$ 45.2	$ 13.3				$ 1.3	$ 19.2	$ 6.4	$ 58.5		$ 26.9		$ 65.7
Merger and acquisition expense	3.6	6.4			$ 4.8	5.9	7.2	5.8	10.0		23.7		21.8
Tax benefit associated with restructuring	8.9	1.2				0.5	4.4	1.0	10.1		6.0		3.7
Tax benefits related to partial reversal of a gain with customer contract expiration						0.4
Tax benefit associated with merger and acquisition expense	0.7	0.3							1.0				3.8
Tax benefit associated with asset impairment expense	18.2					27.6			18.2
Tax impact of other tax adjustments	(7.9)	$ 5.1	$ 3.2	$ (3.4)	4.9	$ 2.4	0.3	$ 1.0	3.8		8.6		9.9
Tax reform adjustments to provision for income taxes	$ 273.5								273.5		0.0		0.0
Tax expense on gain from customer contract expiration							$ 2.6				2.2
Lease termination settlement				$ 5.3					5.3		0.0		0.0
Asbestos-related charge									0.0		703.6		0.0
Intangible asset impairment									0.0		12.6		0.0
Asset impairment and loss on divestiture					20.6				$ 71.0		127.1		$ 0.0
Tax benefits associated with asbestos-related charge					263.0						263.0
Tax benefits associated with intangible asset impairment					4.4						4.4
Tax benefits associated with loss on divestiture					$ (4.9)						$ 22.7

[1] *Net of income taxes.