Basis of Presentation - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reporting segments | segment	1
Unbilled receivables	$ 3.0	$ 2.7
Increase in deferred revenue	(0.3)
Deferred revenue, additional invoicing	0.8
Deferred revenue recognized	1.2
Deferred revenue recognized that was included in the balance at the beginning of the period	0.7
Deferred revenue	1.8
Deferred revenue, long-term	$ 0.1