Discontinued Operations - Narrative (Details) $ in Millions			12 Months Ended
	Oct. 01, 2018 USD ($) shares	Mar. 07, 2018 company	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating segments | segment			2
Cash paid to company for direct sales of assets and liabilities			$ 0.0	$ 21.5	$ 9.0
A&S Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration, number of shares (in shares) | shares	15,800,000
A&S Business | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating segments | company		4
Consideration	$ 2,700.0
Exchange offer	$ 1,300.0
Consideration, number of shares (in shares) | shares	15,824,931
Cash paid to company for direct sales of assets and liabilities	$ 1,000.0
Debt-for-debt exchange	250.0
Cash paid to company as a dividend	$ 150.0
After tax gain on transaction			1,900.0
Pretax transaction-related costs			$ 77.0
A&S Business | Discontinued Operations | Stevens Holding Company, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stockholders right to exchange (in shares) | shares	35,000,000