Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings per share:
Net earnings attributable to BorgWarner Inc.	$ 203.8	$ 184.9	$ 700.7	$ 586.1
Weighted average shares of common stock outstanding	207,471,000	209,803,000	208,505,000	210,657,000
Basic earnings per share of common stock	$ 0.98	$ 0.88	$ 3.36	$ 2.78
Diluted earnings per share:
Net earnings attributable to BorgWarner Inc.	$ 203.8	$ 184.9	$ 700.7	$ 586.1
Weighted average shares of common stock outstanding	207,471,000	209,803,000	208,505,000	210,657,000
Effect of stock-based compensation	1,267,000	1,210,000	1,282,000	918,000
Weighted average shares of common stock outstanding including dilutive shares	208,738,000	211,013,000	209,787,000	211,575,000
Diluted earnings per share of common stock	$ 0.98	$ 0.88	$ 3.34	$ 2.77
Awards Granted in 2016 [Member] | Performance Shares [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	174,400		174,400
Awards Granted in 2018 [Member] | Performance Shares [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	174,750		174,750