Interim Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended								12 Months Ended
	Oct. 30, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Gain on derecognition of subsidiary	$ 177.0									$ 177.0	$ 0.0	$ 0.0
Net sales		$ 2,559.0	$ 2,492.0	$ 2,551.0	$ 2,566.0	$ 2,574.0	$ 2,478.0	$ 2,694.0	$ 2,784.0	10,168.0	10,530.0	9,799.0
Cost of sales		2,014.0	1,968.0	2,038.0	2,047.0	2,030.0	1,963.0	2,114.0	2,193.0	8,067.0	8,300.0	7,684.0
Gross profit		545.0	524.0	513.0	519.0	544.0	515.0	580.0	591.0	2,101.0	2,230.0	2,115.0
Selling, general and administrative expenses		205.0	230.0	212.0	226.0	226.0	230.0	237.0	253.0	873.0	946.0	899.0
Other (income) expense, net		(138.0)	18.0	16.0	29.0	52.0	7.0	30.0	5.0	(75.0)	94.0	144.0
Operating income		478.0	276.0	285.0	264.0	266.0	278.0	313.0	333.0	1,303.0	1,190.0	1,072.0
Equity in affiliates’ earnings, net of tax		(7.0)	(7.0)	(9.0)	(9.0)	(11.0)	(15.0)	(13.0)	(10.0)	(32.0)	(49.0)	(51.0)
Interest income		(3.0)	(4.0)	(2.0)	(3.0)	(2.0)	(1.0)	(1.0)	(2.0)	(12.0)	(6.0)	(6.0)
Interest expense		12.0	15.0	14.0	14.0	14.0	14.0	15.0	16.0	55.0	59.0	71.0
Other postretirement income		1.0	(1.0)	27.0	0.0	(2.0)	(3.0)	(2.0)	(3.0)	27.0	(10.0)	(5.0)
Earnings before income taxes and noncontrolling interest		475.0	273.0	255.0	262.0	267.0	283.0	314.0	332.0	1,265.0	1,196.0	1,063.0
Provision for income taxes		238.0	66.0	73.0	91.0	19.0	67.0	30.0	95.0	468.0	211.0	580.0
Net earnings (loss)		237.0	207.0	182.0	171.0	248.0	216.0	284.0	237.0	797.0	985.0	483.0
Net earnings attributable to the noncontrolling interest, net of tax		17.0	13.0	10.0	11.0	18.0	12.0	12.0	12.0	51.0	54.0	43.0
Net earnings attributable to BorgWarner Inc.		$ 220.0	$ 194.0	$ 172.0	$ 160.0	$ 230.0	$ 204.0	$ 272.0	$ 225.0	$ 746.0	$ 931.0	$ 440.0
Earnings per share — basic		$ 1.07	$ 0.94	$ 0.84	$ 0.77	$ 1.11	$ 0.98	$ 1.30	$ 1.07	$ 3.63	$ 4.47	$ 2.09
Earnings per share — diluted		$ 1.06	$ 0.94	$ 0.83	$ 0.77	$ 1.10	$ 0.98	$ 1.30	$ 1.07	$ 3.61	$ 4.44	$ 2.08
Restructuring expense		$ 31.0	$ 14.0	$ 13.0	$ 14.0	$ 23.0	$ 6.0	$ 31.0	$ 8.0	$ 72.0	$ 67.0	$ 58.0
Business acquisition, percentage of voting interests acquired			20.00%	20.00%
Professional Fees			$ 4.0	$ 5.0	1.0
Litigation Settlement, Expense					14.0
Effective Income Tax Rate Reconciliation, Deduction, Other Postretirement Expense, Amount				6.0						6.0
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act, Transition Tax on Accumulated Foreign Earnings, Amount					22.0
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		7.0
Effective Income Tax Rate Reconciliation, Global Realignment Plan		11.0
Gain on sale of building						19.0				0.0	19.0	0.0
Merger, acquisition and divestiture expense						1.0	2.0	1.0	2.0	11.0	6.0	10.0
Asset impairment expense						26.0				7.0	25.0	71.0
Asbestos-related adjustments						23.0				0.0	23.0	0.0
Lease termination settlement										0.0	0.0	5.0
Tax benefit associated with restructuring		8.0	4.0	4.0	3.0	6.0	1.0	8.0	1.0	19.0	15.0	10.0
Effective rate reconciliation measurement period adjustments due to the Tax Act						7.0	(7.0)	(13.0)			(13.0)
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount							(1.0)	(21.0)			(22.0)
Valuation allowance adjustments						9.0				2.0	11.0	(12.0)
Effective income tax rate reconciliation, tax reserve adjustments						(3.0)					(3.0)
Effective Income Tax Rate Reconciliation, Disposition of Asset, Amount						6.0					6.0
Tax benefit associated with merger and acquisition expense												(1.0)
Tax benefit associated with asset impairment expense						8.0					8.0	18.0
Tax impact of other tax adjustments		$ 5.0	$ 9.0	$ 1.0	$ 5.0	19.0	$ 2.0	$ 10.0			30.0	4.0
Tax expenses (benefits) associated with asbestos-related adjustments						$ (6.0)					(6.0)
Tax reform adjustments to provision for income taxes										16.0	(13.0)	274.0
Tax expense on gain from customer contract expiration									1.0		1.0
Gain on commercial settlement									$ 4.0	$ 0.0	$ 4.0	$ 0.0