Basis of Presentation and Summary of Significant Accounting Policies - Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue - current	$ 28,227	$ 33,558
Accumulated deficit	$ (152,675)	(134,855)
As Originally Reported | Accounting Standards Update 2014-09
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue - current		22,500
Accumulated deficit		(123,797)
Effect of Change | Accounting Standards Update 2014-09
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue - current		11,058
Accumulated deficit		$ (11,058)