Recent Transactions (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			9 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018	Sep. 27, 2017	Nov. 10, 2015
Business Acquisition [Line Items]
Payments for businesses acquired, net of cash acquired					$ 0.0	$ 185.7	$ 0.0
Goodwill	$ 1,881.8				1,853.4	1,881.8
Proceeds from sale of businesses, net of cash divested					0.0	0.0	85.8
Asset impairment and loss on divestiture					25.6	71.0	127.1
Assets	9,787.6	$ 8,834.7			10,095.3	9,787.6	$ 8,834.7
Inventories, net	766.3				780.8	$ 766.3			$ 758.9
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%
Payments for businesses acquired, net of cash acquired						$ 185.7
Business Combination, Consideration Transferred, Liabilities Incurred				$ 26.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables										$ 15.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory										16.7
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										127.6
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										(9.2)
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										(2.9)
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					(6.0)
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											$ 29.50
Payments for businesses acquired, net of cash acquired								$ 1,187.0
Business Combination, Consideration Transferred, Liabilities Incurred					$ 361.0
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]
Noncontrolling Interest, Parent Ownership of Interests Sold							60.00%
Proceeds from sale 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