Basis of Presentation and Summary of Significant Accounting Policies - Insurance Subsidiary (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for policy claims	$ 60.9	$ 61.5
Other Current Liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for policy claims	13.2	13.2
Other Noncurrent Liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for policy claims	$ 47.7	$ 48.3