Reporting Segments (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment				2
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue		$ 1,884.0	$ 2,032.1	$ 5,900.1	$ 6,313.2
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT		282.2	290.6	883.7	933.6
Restructuring expense		9.3	13.1	41.3	67.6
Merger and acquisition expense		3.9		3.9
Gain on previously held equity interest				(10.8)
Corporate, including equity in affiliates' earnings and stock-based compensation		23.2	22.3	81.8	76.0
Interest income		(2.0)	(1.4)	(5.3)	(4.3)
Interest expense and finance charges		15.0	9.0	42.6	26.2
Earnings before income taxes and noncontrolling interest		232.8	244.9	730.2	765.4
Provision for income taxes		66.9	71.9	219.2	225.3
Net earnings		165.9	173.0	511.0	540.1
Net earnings attributable to the noncontrolling interest, net of tax		8.5	6.4	26.6	24.2
Net earnings attributable to BorgWarner Inc.		157.4	166.6	484.4	515.9
Segment Reporting Information - Assets
Total assets		7,687.1		7,687.1		$ 7,228.0
Operating Segments [Member]
Segment Reporting Information - Assets
Total assets		5,912.6		5,912.6		5,719.7
Engine [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue		1,308.9	1,412.4	4,102.8	4,322.0
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT		211.9	222.6	670.3	696.0
Segment Reporting Information - Assets
Total assets		4,032.2		4,032.2		3,936.2
Drivetrain [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue		583.7	627.0	1,821.8	2,016.4
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT		70.3	68.0	213.4	237.6
Segment Reporting Information - Assets
Total assets		1,880.4		1,880.4		1,783.5
Intersegment Eliminations [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue		(8.6)	(7.3)	(24.5)	(25.2)
Corporate Segment [Member]
Segment Reporting Information - Assets
Total assets	[1]	1,774.5		1,774.5		$ 1,508.3
Remy International Inc
Adjusted earnings before interest, income taxes and noncontrolling interest
Merger and acquisition expense			0.0		0.0
BERU Diesel Start Systems Pvt. Ltd.
Adjusted earnings before interest, income taxes and noncontrolling interest
Gain on previously held equity interest		0.0	0.0	(10.8)	0.0
United States Pension Plan of US Entity [Member]
Segment Reporting Information - Assets
Settlement		$ 0.0	$ 2.7	$ 0.0	$ 2.7

[1] Corporate assets include investments and other long-term receivables and deferred income taxes.