Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
	Feb. 05, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Loss Contingencies [Line Items]
Base rent expense (less than)		$ 0.1	$ 0.1
Cash paid for operating lease liabilities (less than)		$ 0.1
Amount settled in mediation	$ 0.4
Natural Disasters and Other Casualty Events
Loss Contingencies [Line Items]
Insurance proceeds				$ 1.1
Natural Disasters and Other Casualty Events | Cost of Sales
Loss Contingencies [Line Items]
Insurance proceeds				0.6
Natural Disasters and Other Casualty Events | Other Income, Net
Loss Contingencies [Line Items]
Insurance proceeds				$ 0.5