Earnings Per Share (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Basic earnings per share:
Net earnings attributable to BorgWarner Inc.	$ 178.9us-gaap_NetIncomeLoss	$ 159.1us-gaap_NetIncomeLoss
Weighted average shares of common stock outstanding	225,796	227,430
Basic earnings per share of common stock	$ 0.79us-gaap_EarningsPerShareBasic	$ 0.70us-gaap_EarningsPerShareBasic
Diluted earnings per share:
Net earnings attributable to BorgWarner Inc.	$ 178.9us-gaap_NetIncomeLoss	$ 159.1us-gaap_NetIncomeLoss
Weighted average shares of common stock outstanding	225,796	227,430
Effect of stock-based compensation	1,292	1,897
Weighted average shares of common stock outstanding including dilutive shares	227,088	229,327
Diluted earnings per share of common stock	$ 0.79us-gaap_EarningsPerShareDiluted	$ 0.69us-gaap_EarningsPerShareDiluted

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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