Reporting Segments and Related Information - Quarterly Information (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net sales	$ 1,991.9	$ 2,032.1	$ 2,197.0	$ 2,084.1	$ 1,885.4	$ 1,806.2	$ 1,893.9	$ 1,851.1	$ 8,305.1	$ 7,436.6	$ 7,183.2
Cost of sales	1,578.6	1,607.6	1,724.2	1,638.3	1,478.8	1,426.6	1,497.3	1,476.4	6,548.7	5,879.1	5,716.3
Gross profit	413.3	424.5	472.8	445.8	406.6	379.6	396.6	374.7	1,756.4	1,557.5	1,466.9
Selling, general and administrative expenses	169.4	174.5	181.2	173.8	167.1	157.7	155.6	159.3	698.9	639.7	629.3
Other expense, net	31.7	12.3	11.0	38.8	51.8	(3.7)	(2.4)	16.9	93.8	62.6	84.7
Operating income	212.2	237.7	280.6	233.2	187.7	225.6	243.4	198.5	963.7	855.2	752.9
Equity in affiliates’ earnings, net of tax	(11.5)	(14.8)	(12.2)	(8.8)	(12.3)	(10.4)	(11.1)	(9.7)	(47.3)	(43.5)	(42.8)
Interest income	(1.2)	(1.4)	(1.4)	(1.5)	(1.5)	(1.3)	(1.0)	(1.0)	(5.5)	(4.8)	(4.7)
Interest expense and finance charges	10.2	9.0	9.0	8.2	7.6	8.1	8.8	9.7	36.4	34.2	39.4
Earnings before income taxes and noncontrolling interest	214.7	244.9	285.2	235.3	193.9	229.2	246.7	199.5	980.1	869.3	761.0
Provision for income taxes	67.3	71.9	85.3	68.1	44.5	56.3	66.6	50.9	292.6	218.3	238.6
Net earnings	147.4	173.0	199.9	167.2	149.4	172.9	180.1	148.6	687.5	651.0	522.4
Net earnings attributable to the noncontrolling interest, net of tax	7.5	6.4	9.7	8.1	8.0	6.1	6.0	6.6	31.7	26.7	21.5
Net earnings attributable to BorgWarner Inc.	139.9	166.6	190.2	159.1	141.4	166.8	174.1	142.0	655.8	624.3	500.9
Earnings per share — basic	$ 0.62	$ 0.73	$ 0.84	$ 0.70	$ 0.62	$ 0.73	$ 0.76	$ 0.62	$ 2.89	$ 2.73	$ 2.22
Earnings per share — diluted	$ 0.61	$ 0.73	$ 0.83	$ 0.69	$ 0.62	$ 0.72	$ 0.75	$ 0.61	$ 2.86	$ 2.70	$ 2.09	[1]
Retirement related obligations										5.9	17.3
Tax benefit of project termination settlement								3.8
Pension settlement loss											5.7
Executive retirement incremental compensation expense											11.6
Tax benefit associated retirement obligations								2.1
Other tax adjustments						5.6		1.7		11.7	19.8
Tax impact of writedown of tax accounts											11.1
Loss from disposal activities											39.7
Tax impact of loss on disposals											5.7
Restructuring expense	17.8	9.6	13.0	38.4	35.8				90.8	39.8	27.4
Intangible asset impairment					12.5				10.3	12.5
Tax benefit associated with restructuring	3.4	1.4	1.7	8.8					15.3	5.1	7.7
Tax benefit on intangible asset impairment	0.4				2.0
Impact of change in repatriation assertion											7.5
Other tax benefits	0.2	0.9				3.1			1.1	2.2
Reversal of certain state valuation allowances					4.4	2.5				8.0
Program termination agreement										11.3
Tax benefit of research and development and international tax credit extensions								6.6		6.7
Tax impact of other tax adjustments								4.9		5.2
Corporate and Other [Member]
Restructuring expense	5.4	3.5	2.0	1.1	4.0				12.0	4.0
U.S. Plans:
Pension settlement loss	$ 0.4	$ 2.7							$ 3.1	$ 0	$ 0

[1] * The Company's diluted earnings per share for the year ended December 31, 2012 includes the impact of the Company's 3.50% convertible senior notes and associated warrants. Refer to the Earnings Per Share footnote to the Consolidated Financial Statements for further information on the diluted earnings per share calculation.