Reporting Segments (Details) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)	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		$ 2,031.9	$ 2,197.0	$ 4,016.1	$ 4,281.1
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT		300.1	330.8	601.5	643.0
Restructuring expense		19.9	15.0	32.0	54.5
Gain on previously held equity interest				(10.8)
Corporate, including equity in affiliates' earnings and stock-based compensation		26.6	23.0	58.6	53.7
Interest income		(1.6)	(1.4)	(3.3)	(2.9)
Interest expense and finance charges		17.6	9.0	27.6	17.2
Earnings before income taxes and noncontrolling interest		237.6	285.2	497.4	520.5
Provision for income taxes		80.2	85.3	152.3	153.4
Net earnings		157.4	199.9	345.1	367.1
Net earnings attributable to the noncontrolling interest, net of tax		9.3	9.7	18.1	17.8
Net earnings attributable to BorgWarner Inc.		148.1	190.2	327.0	349.3
Segment Reporting Information - Assets
Total assets		7,766.3		7,766.3		$ 7,228.0
Operating Segments [Member]
Segment Reporting Information - Assets
Total assets		5,907.6		5,907.6		5,719.7
Engine [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue		1,413.0	1,497.5	2,793.9	2,909.6
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT		228.0	241.7	458.4	473.4
Segment Reporting Information - Assets
Total assets		4,043.2		4,043.2		3,936.2
Drivetrain [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue		626.9	708.7	1,238.1	1,389.4
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT		72.1	89.1	143.1	169.6
Segment Reporting Information - Assets
Total assets		1,864.4		1,864.4		1,783.5
Intersegment Eliminations [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue		(8.0)	(9.2)	(15.9)	(17.9)
Corporate Segment [Member]
Segment Reporting Information - Assets
Total assets	[1]	1,858.7		1,858.7		$ 1,508.3
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

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