Reporting Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended			12 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011	Dec. 31, 2008	Dec. 31, 2011
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	$ 1,856.4		$ 1,818.8	$ 3,768.9		$ 3,549.2
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT	265.1		236.1	536.1		454.2
Loss from disposal activities	37.9		0	37.9		0
Gain (Loss) Related to Litigation Settlement	0		(29.1)	0		(29.1)	(4.0)
Corporate, including equity in affiliates' earnings and stock-based compensation	21.2		28.8	57.3		59.2
Interest income	(1.3)		(1.2)	(2.7)		(2.2)
Interest expense and finance charges	12.6		20.5	27.7		38.9
Earnings before income taxes and noncontrolling interest	194.7		217.1	415.9		387.4
Provision for income taxes	68.5		49.8	126.0		90.7
Net earnings	126.2		167.3	289.9		296.7
Net earnings attributable to the noncontrolling interest, net of tax	5.6		5.3	11.3		10.2
Net earnings attributable to BorgWarner Inc.	120.6		162.0	278.6		286.5
Segment Reporting Information - Assets
Total assets	6,220.7			6,220.7				5,958.6
Operating Segments [Member]
Segment Reporting Information - Assets
Total assets	5,021.9			5,021.9				4,891.8
Engine [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	1,269.6		1,297.9	2,577.8		2,547.3
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT	210.5		197.2	420.3		383.3
Segment Reporting Information - Assets
Total assets	3,390.4			3,390.4				3,329.0
Drivetrain [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	593.9		525.7	1,205.3		1,012.1
Adjusted earnings before interest, income taxes and noncontrolling interest
Adjusted EBIT	54.6		38.9	115.8		70.9
Segment Reporting Information - Assets
Total assets	1,631.5			1,631.5				1,562.8
Intersegment Elimination [Member]
Net Sales by Reporting Segment
Segment Reporting, Entity Consolidated Revenue	(7.1)		(4.8)	(14.2)		(10.2)
Corporate [Member]
Segment Reporting Information - Assets
Total assets	$ 1,198.8	[1]		$ 1,198.8	[1]			$ 1,066.8	[1]

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