Assets and Liabilities Held for Sale (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset impairment expense		$ 25.6	$ 71.0	$ 25.6	$ 71.0	$ 127.1
Costs to sell				3.5
Receivables, net		14.8	21.0	14.8	21.0
Inventories, net		41.6	30.4	41.6	30.4
Prepayments and other current assets		11.9	10.3	11.9	10.3
Property, plant and equipment, net		44.9	47.7	44.9	47.7
Goodwill		7.0	7.3	7.0	7.3
Other intangible assets, net		20.2	21.1	20.2	21.1
Other assets		0.1	0.5	0.1	0.5
Impairment of carrying value		(93.5)	(71.0)	(93.5)	(71.0)
Total assets held for sale		47.0	67.3	47.0	67.3
Accounts payable and accrued expenses		18.3	24.6	18.3	24.6
Other liabilities		4.8	4.9	4.8	4.9
Total liabilities held for sale		$ 23.1	$ 29.5	$ 23.1	$ 29.5
Scenario, Forecast [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses	$ 28.0