Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 15, 2018	Dec. 31, 2017
Supplemental Balance Sheet Disclosures [Line Items]
Income taxes receivable	$ 2.1
Required contributions by employer	1.7	$ 1.7	$ 0.0
Other Noncurrent Assets
Supplemental Balance Sheet Disclosures [Line Items]
Income taxes receivable	2.1
Equity securities	4.0
Other Current Liabilities
Supplemental Balance Sheet Disclosures [Line Items]
Levy accruals	5.4		5.6
Accrued payroll	0.2		0.6
Other Liabilities
Supplemental Balance Sheet Disclosures [Line Items]
Pension liabilities	$ 20.9		$ 24.3