Acquisitions Acquisitions (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Oct. 05, 2015	Mar. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 774.7	$ 778.3			$ 632.1
Wolverine Advanced Materials Acquisition [Member]
Business Acquisition [Line Items]
Cash			$ 8.5
Receivables			31.6
Inventory			35.0
Plant, property and equipment			28.5
Goodwill			164.2
Other intangible assets			86.0
Other assets			10.7
Accounts payable and accrued liabilities			(21.2)
Postretirement liabilities			(14.6)
Other liabilities			(13.2)
Net assets acquired			$ 315.5
Hartzell Aerospace Acquisition [Member]
Business Acquisition [Line Items]
Cash				$ 0.0
Receivables				5.3
Inventory				4.8
Plant, property and equipment				2.6
Goodwill				13.7
Other intangible assets				28.6
Other assets				0.9
Accounts payable and accrued liabilities				(3.0)
Postretirement liabilities				0.0
Other liabilities				0.0
Net assets acquired				$ 52.9