Supplemental Balance Sheet Information - Schedule of Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet Related Disclosures [Abstract]
Accrued payroll	$ 1.5	$ 2.6
Deferred revenue	7.2	6.7
Restructuring accruals	0.3	0.0
Levy accruals	5.6	4.9
Other current liabilities	2.1	1.8
Total other current liabilities	$ 16.7	$ 16.0