Acquisitions Acquisitions Textuals (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 26, 2017	Oct. 05, 2015	Mar. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 886.8	$ 774.7	$ 778.3
Axtone Railway Components Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Jan. 26, 2017
Business Acquisition, Name of Acquired Entity	Axtone Railway Components (Axtone)
Payments to Acquire Businesses, Gross	$ 123.1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net				$ 123.1
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period		$ 72.0
Goodwill				$ 83.0
Wolverine Advanced Materials Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Oct. 05, 2015
Business Acquisition, Name of Acquired Entity	Wolverine Advanced Materials LLC (Wolverine)
Payments to Acquire Businesses, Gross			307.0
Goodwill					$ 164.2
Hartzell Aerospace Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Mar. 31, 2015
Business Acquisition, Name of Acquired Entity	Environmental Control Systems (f/k/a Hartzell Aerospace)
Payments to Acquire Businesses, Gross			$ 52.9
Goodwill						$ 13.7