Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic earnings per share [Abstract]
Net earnings attributable to BorgWarner Inc.	$ 230.0	$ 203.8	$ 271.8	$ 225.1	$ (146.2)	$ 184.9	$ 212.0	$ 189.2	$ 930.7	$ 439.9	$ 595.0
Weighted average shares of common stock outstanding									208,197	210,429	214,374
Earnings per share — basic	$ 1.11	$ 0.98	$ 1.30	$ 1.07	$ (0.70)	$ 0.88	$ 1.01	$ 0.89	$ 4.47	$ 2.09	$ 2.78
Diluted earnings per share [Abstract]
Net earnings attributable to BorgWarner Inc.	$ 230.0	$ 203.8	$ 271.8	$ 225.1	$ (146.2)	$ 184.9	$ 212.0	$ 189.2	$ 930.7	$ 439.9	$ 595.0
Effect of stock-based compensation									1,299	1,119	954
Weighted average shares of common stock outstanding including dilutive shares									209,496	211,548	215,328
Earnings per share — diluted	$ 1.10	$ 0.98	$ 1.30	$ 1.07	$ (0.70)	$ 0.88	$ 1.00	$ 0.89	$ 4.44	$ 2.08	$ 2.76
Performance Shares [Member]
Diluted earnings per share [Abstract]
Antidilutive stock-based awards excluded from the calculation of diluted earnings per share									139