Reporting Segments and Related Information - Adjusted EBIT (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Adjusted EBIT																	$ 995.5		$ 935.5		$ 674.9
Loss on disposals																	(39.7)		(21.5)		0
Restructuring expense																	27.4		0		0
Retirement related obligations																	17.3		0		0
Patent infringement settlement, net of legal costs incurred																	0		29.1		0
Environmental litigation settlement																	0		0		28.0
BERU - Eichenauer equity investment gain																	0		0		(8.0)
Corporate, including equity in affiliates' earnings and stock-based compensation																	115.4		107.4		111.0
Interest income	1.0		1.0		1.3		1.4		1.3		1.3		1.2		1.0		4.7		4.8		2.8
Interest expense and finance charges	6.7		5.0		12.6		15.1		17.2		18.5		20.5		18.4		39.4		74.6		68.8
Earnings before income taxes and noncontrolling interest	175.0		170.1		194.7		221.2		185.4		193.1		217.1		170.3		761.0		765.9		477.9
Provision for income taxes	48.4		64.2		68.5		57.5		58.2		46.4		49.8		40.9		238.6		195.3		81.7
Net earnings	126.6		105.9		126.2		163.7		127.2		146.7		167.3		129.4		522.4		570.6		396.2
Net earnings attributable to the noncontrolling interest, net of tax	5.4		4.8		5.6		5.7		5.2		5.1		5.3		4.9		21.5		20.5		18.8
Net earnings attributable to BorgWarner Inc.	121.2	[1]	101.1	[1]	120.6	[1]	158.0	[1]	122.0	[1]	141.6	[1]	162.0	[1]	124.5	[1]	500.9	[1]	550.1	[1]	377.4
Engine [Member]
Segment Reporting Information [Line Items]
Adjusted EBIT																	786.4		774.3		537.9
Drivetrain [Member]
Segment Reporting Information [Line Items]
Adjusted EBIT																	$ 209.1		$ 161.2		$ 137.0

[1] The Company's results were impacted by the following:•Quarter ended December 31, 2012: Retirement related obligations of $17.3 million are comprised of a $5.7 million loss resulting from the settlement of a portion of the Muncie Plant's pension obligation and an $11.6 million expense associated with the retirement of certain Named Executive Officers. These obligations were partially offset by a $6.1 million tax benefit. The Company incurred tax expense of $3.9 million which included $11.1 million of U.S. tax expense to correct the income taxes payable balance, partially offset by tax benefits resulting from changes to the statutory income tax rate in certain countries and the settlement of certain tax audits. •Quarter ended September 30, 2012: The Company incurred $1.8 million of expense and $11.2 million of tax expense associated with the completion of the sale of its spark plug business. The Company also recorded restructuring expense of $27.4 million primarily associated with the disposal and future requirements of BERU's on-going business, which was partially offset by a tax benefit of $7.7 million. Additionally, the Company incurred tax expense of $6.9 million primarily resulting from the settlement of certain tax audits.•Quarter ended June 30, 2012: The Company recorded expense of $37.9 million primarily due to the write-down of prior purchase price accounting adjustments included within the disposal group as a result of signing a Master Purchase Agreement to sell the spark plug business to Federal-Mogul Corporation, which was partially offset by a tax benefit of $5.5 million resulting from the write-down. Additionally, the Company recorded tax expense of $9.0 million related to its decision to change its cash repatriation assertion for some of its foreign subsidiaries.•Quarter ended December 31, 2011: The Company incurred $21.5 million in expense associated with the loss on sale of the tire pressure monitoring business, including costs related to the divestiture, and a write-down of a portion of the ignitor and electronic business. The Company recorded $1.4 million of tax benefit associated with the disposals and $4.1 million of tax expense related to an intercompany disposal transaction.•Quarter ended June 30, 2011: The Company recorded a $29.1 million patent infringement settlement gain, net of legal costs incurred, which was partially offset by $11.0 million of additional tax expense. Additionally, the Company recorded $6.2 million related to tax adjustments resulting from a change in state corporate income tax legislation as well as an adjustment of the Company's tax accounts as a result of the closure of certain tax audits.