Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2011

Earnings Per Share [Abstract]

Schedule of Earnings per Share reconciliation [Text Block]

The following table reconciles the numerators and denominators used to calculate basic and diluted earnings per share of common stock:

	Year Ended December 31,
(in millions except per share amounts)	2011		2010		2009
Basic earnings per share:
Net earnings attributable to BorgWarner Inc.	$	550.1	$	377.4	$	27.0
Weighted average shares of common stock outstanding	109.229		114.155		116.522
Basic earnings per share of common stock	$	5.04	$	3.31	$	0.23
Diluted earnings per share:
Net earnings attributable to BorgWarner Inc.	$	550.1	$	377.4	$	27.0
Adjusted for net interest expense on convertible notes	21.5		20.4		—
Diluted net earnings attributable to BorgWarner Inc.	$	571.6	$	397.8	$	27.0
Weighted average shares of common stock outstanding	109.229		114.155		116.522
Effect of 3.50% convertible senior notes	11.389		11.389		—
Effect of warrant	5.215		1.464		—
Effect of stock-based compensation	2.635		2.567		0.417
Total dilutive effect on weighted average shares of common stock outstanding	19.239		15.420		0.417
Weighted average shares of common stock outstanding including dilutive shares	128.468		129.575		116.939
Diluted earnings per share of common stock	$	4.45	$	3.07	$	0.23
Anti-dilutive shares:
3.50% convertible senior notes	—		—		11.389
Bond hedge	6.141		2.836		0.034
Stock-based compensation	—		—		2.711
Total anti-dilutive shares	6.141		2.836		14.134