Recent Transactions (Details) $ / shares in Units, ₨ in Millions, $ in Millions			3 Months Ended				12 Months Ended
	Jan. 29, 2015 USD ($)	Jan. 29, 2015 INR (₨)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 27, 2017 USD ($)	Nov. 10, 2015 $ / shares
Business Acquisition [Line Items]
Noncontrolling Interest, Parent Ownership of Interests Sold								60.00%
Gain on previously held equity interest							$ 0.0	$ 0.0	$ 10.8
Payments for businesses acquired, net of cash acquired							185.7	0.0	1,199.6
Goodwill			$ 1,881.8		$ 1,702.2		1,881.8	1,702.2
Proceeds from divestiture of businesses, net of cash divested							0.0	85.8	0.0
Noncontrolling Interest, Decrease from Deconsolidation								4.8
Asset Impairment Charges			71.0			$ 106.5
Asset impairment and loss on divestiture					20.6		71.0	127.1	0.0
Assets			9,787.6		8,834.7		9,787.6	8,834.7	$ 8,825.7
Inventories, net			$ 766.3		641.2		$ 766.3	641.2
Sevcon, Inc [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition							Sep. 27, 2017
Business acquisition, percentage of voting interests acquired			100.00%				100.00%			100.00%
Business Combination, Consideration Transferred, Other				$ 26.6
Payments for businesses acquired, net of cash acquired							$ 185.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables										$ 15.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory										18.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other										2.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment										7.3
Goodwill										125.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles										70.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent										(9.5)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other										0.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Assets and Liabilities										2.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable										(24.5)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net										203.7
Liabilities assumed from businesses acquired										(18.0)
Goodwill, Purchase Accounting Adjustments							$ (7.8)
Business Combination, Consideration Transferred			$ 5.1
Remy International Inc. [Member]
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired									100.00%
Business Acquisition, Share Price | $ / shares											$ 29.50
Business Combination, Consideration Transferred, Other								361.0
Payments for businesses acquired, net of cash acquired									$ 1,187.0
BERU Diesel Start Systems Pvt. Ltd.
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	51.00%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage	100.00%
Gain on previously held equity interest									10.8
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	$ 4.6
Payments for businesses acquired, net of cash acquired		₨ 783.1							$ 12.6
Business Acquisition, Goodwill, Nondeductible Amount	13.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	16.0
Noncash or Part Noncash Acquisition, Value of Assets Acquired	$ 11.2
Customer Relationships [Member] | Sevcon, Inc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill										17.7
Developed Technology Rights [Member] | Sevcon, Inc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill										48.8
Trade Names [Member] | Sevcon, Inc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill										$ 4.2
Minimum [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life							7 years
Maximum [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life							20 years
Divgi-Warner [Member]
Business Acquisition [Line Items]
Proceeds from divestiture of businesses, net of cash divested								5.4
Noncontrolling Interest, Decrease from Deconsolidation								4.8
Remy light vehicle aftermarket business [Member]
Business Acquisition [Line Items]
Proceeds from Divestiture of Businesses								80.0
Asset Impairment Charges						$ 106.5
Asset impairment and loss on divestiture					(20.6)			(127.1)
Assets					284.1			284.1
Inventories, net					94.7			94.7
Accounts Receivable, Net, Current					72.6			72.6
Liabilities					$ 93.2			$ 93.2