Supplemental Balance Sheet Information - Schedule of Accounts Receivable Reserves and Allowances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Reserves and allowances, beginning balance	$ 0.2	$ 0.6
Additions	0.2	0.1
Write-offs, net of recoveries	0.0	(0.5)
Reserves and allowances, ending balance	$ 0.4	$ 0.2