Description of Operations and Summary of Significant Accounting Policies - Summary of Select Unaudited Condensed Consolidated Statement of Cash Flows Reflect Adoption of Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net loss	$ (4,570)	$ (4,112)		$ (17,966)	$ (18,163)
Adjustments to reconcile net loss to net cash provided by operating activities:
Amortization of deferred costs				12,222	10,093	[1]
Foreign exchange loss (gain)				797	(159)	[1]
Change in operating assets and liabilities
Deferred costs				(13,611)	(10,648)	[1]
Net cash provided by operating activities				7,839	10,903	[1]
Foreign currency effect on cash, cash equivalents and restricted cash				(488)	(585)	[1]
Net decrease in cash, cash equivalents and restricted cash				122,608	(12,728)	[1]
Cash, cash equivalents and restricted cash
End of period	$ 177,677	29,279	[1]	$ 177,677	29,279	[1]
ASU 2014-09 | As Previously Reported
Cash flows from operating activities
Net loss		(5,171)			(18,731)
Adjustments to reconcile net loss to net cash provided by operating activities:
Foreign exchange loss (gain)					(173)
Change in operating assets and liabilities
Net cash provided by operating activities					10,876
Foreign currency effect on cash, cash equivalents and restricted cash					(558)
Net decrease in cash, cash equivalents and restricted cash					(12,728)
Cash, cash equivalents and restricted cash
End of period		29,279			29,279
ASU 2014-09 | Adjustments
Cash flows from operating activities
Net loss		$ 1,059			568
Adjustments to reconcile net loss to net cash provided by operating activities:
Amortization of deferred costs					10,093
Foreign exchange loss (gain)					14
Change in operating assets and liabilities
Deferred costs					(10,648)
Net cash provided by operating activities					27
Foreign currency effect on cash, cash equivalents and restricted cash					$ (27)

[1] See Note 1 for a summary of adjustments