Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic earnings per share [Abstract]
Net earnings attributable to BorgWarner Inc.	$ (146.2)	$ 184.9	$ 212.0	$ 189.2	$ (293.3)	$ 83.3	$ 164.4	$ 164.1	$ 439.9	$ 118.5	$ 609.7
Weighted average shares of common stock outstanding									210,429	214,374	224,414
Earnings per share — basic	$ (0.70)	$ 0.88	$ 1.01	$ 0.89	$ (1.39)	$ 0.39	$ 0.76	$ 0.75	$ 2.09	$ 0.55	$ 2.72
Diluted earnings per share [Abstract]
Net earnings attributable to BorgWarner Inc.	$ (146.2)	$ 184.9	$ 212.0	$ 189.2	$ (293.3)	$ 83.3	$ 164.4	$ 164.1	$ 439.9	$ 118.5	$ 609.7
Effect of stock-based compensation									1,119	954	1,234
Weighted average shares of common stock outstanding including dilutive shares									211,548	215,328	225,648
Earnings per share — diluted	$ (0.70)	$ 0.88	$ 1.00	$ 0.89	$ (1.39)	$ 0.39	$ 0.76	$ 0.75	$ 2.08	$ 0.55	$ 2.70