CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenue	$ 16,821	$ 14,991
Cost of goods sold	1,932	1,526
Gross profit	14,889	13,465
Operating expenses:
Sales and marketing	19,281	15,815
Research and development	2,090	1,683
General and administrative	5,400	4,766
Total operating expenses	26,771	22,264
Loss from operations	(11,882)	(8,799)
Interest and other income (expense), net:
Interest income	498	744
Interest expense	(1,231)	(1,230)
Other expense, net	(157)	(60)
Net loss	(12,772)	(9,345)
Other comprehensive income (loss):
Changes in foreign currency translation	12	(19)
Unrealized gain on marketable securities	221	25
Comprehensive loss	$ (12,539)	$ (9,339)
Net loss per share, basic and diluted (in dollars per share)	$ (0.47)	$ (0.38)
Weighted-average number of common shares used to compute basic and diluted net loss per share (in shares)	27,252,409	24,390,648