Summary of Significant Accounting Policies and Basis of Presentation - Cumulative Adjustments on the Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Inventories — net	$ 198.0	$ 153.4	$ 152.3
Equity:
Retained earnings	$ 230.2	205.6	204.5
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Inventories — net			152.3
Equity:
Retained earnings			$ 204.5
Adjustments Due to ASU 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Assets
Inventories — net		1.1
Equity:
Retained earnings		$ 1.1