Reporting Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011	Dec. 31, 2011
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	$ 1,912.5		$ 1,730.4
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT	271.0		218.1
Corporate, including equity in affiliates' earnings and stock-based compensation	36.1		30.4
Interest income	(1.4)		(1.0)
Interest expense and finance charges	15.1		18.4
Earnings before income taxes and noncontrolling interest	221.2		170.3
Provision for income taxes	57.5		40.9
Net earnings	163.7		129.4
Net earnings attributable to the noncontrolling interest, net of tax	5.7		4.9
Net earnings attributable to BorgWarner Inc.	158.0		124.5
Segment Reporting Information - Assets
Total assets	6,281.3			5,958.6
Operating Segments [Member]
Segment Reporting Information - Assets
Total assets	5,169.4			4,891.8
Engine [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	1,308.2		1,249.4
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT	209.8		186.1
Segment Reporting Information - Assets
Total assets	3,495.9			3,329.0
Drivetrain [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	611.4		486.4
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT	61.2		32.0
Segment Reporting Information - Assets
Total assets	1,673.5			1,562.8
Business Intersegment, Eliminations [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	(7.1)		(5.4)
Corporate [Member]
Segment Reporting Information - Assets
Total assets	$ 1,111.9	[1]		$ 1,066.8	[1]

[1] Corporate assets include investments and advances and deferred income taxes