Description of Operations and Summary of Significant Accounting Policies - Summary of Select Unaudited Condensed Consolidated Statement of Operations Reflect Adoption of Accounting Standards (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating expenses
Sales and marketing	$ 24,024	$ 20,992	$ 46,702	$ 40,609
Loss from operations	(3,870)	(7,169)	(11,943)	(14,466)
Foreign exchange loss	(576)	119	(462)	66
Net loss	$ (5,297)	$ (6,912)	$ (13,396)	$ (14,051)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.12)	$ (0.18)	$ (0.31)	$ (0.36)
ASU 2014-09 | As Previously Reported
Operating expenses
Sales and marketing		$ 21,094		$ 40,120
Loss from operations		(7,271)		(13,977)
Foreign exchange loss		120		68
Net loss		$ (7,013)		$ (13,560)
Net loss per share attributable to common stockholders, basic and diluted		$ (0.18)		$ (0.35)
ASU 2014-09 | Adjustments
Operating expenses
Sales and marketing		$ (102)		$ 489
Loss from operations		102		(489)
Foreign exchange loss		(1)		(2)
Net loss		$ 101		$ (491)
Net loss per share attributable to common stockholders, basic and diluted				$ (0.01)