CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($)	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2016		25,955,759
Beginning balance, amount at Dec. 31, 2016	$ 86,997,000	$ 26,000	$ 252,158,000	$ (1,612,000)	$ (163,575,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock units (in shares)		893,843
Exercise of stock options and vesting of restricted stock units		$ 1,000	1,427,000
Stock-based compensation expense			11,947,000
Statutory tax withholding related to net-share settlement of restricted stock units (in shares)		(247,976)
Statutory tax withholding related to net-share settlement of restricted stock units			(2,727,000)
Net income (loss)	(16,557,000)				(16,557,000)
Foreign currency translation adjustments	823,000			823,000
Ending balance (in shares) at Dec. 31, 2017		26,601,626
Ending balance, amount at Dec. 31, 2017	81,911,000	$ 27,000	262,805,000	(789,000)	(180,132,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock units (in shares)		1,034,146
Exercise of stock options and vesting of restricted stock units	1,106,000	$ 0	1,106,000
Stock-based compensation expense	10,598,000		10,598,000
Statutory tax withholding related to net-share settlement of restricted stock units (in shares)		(288,657)
Statutory tax withholding related to net-share settlement of restricted stock units	(2,959,000)		(2,959,000)
Net income (loss)	(7,601,000)				(7,601,000)
Foreign currency translation adjustments	(918,000)			(918,000)
Ending balance (in shares) at Dec. 31, 2018		27,347,115
Ending balance, amount at Dec. 31, 2018	89,638,000	$ 27,000	271,550,000	(1,707,000)	(180,232,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of restricted stock units (in shares)		1,021,730
Exercise of stock options and vesting of restricted stock units	975,000	$ 1,000	974,000
Stock-based compensation expense	8,976,000		8,976,000
Statutory tax withholding related to net-share settlement of restricted stock units (in shares)		(291,376)
Statutory tax withholding related to net-share settlement of restricted stock units	(3,389,000)		(3,389,000)
Net income (loss)	3,482,000				3,482,000
Foreign currency translation adjustments	(33,000)			(33,000)
Ending balance (in shares) at Dec. 31, 2019		28,077,469
Ending balance, amount at Dec. 31, 2019	$ 99,649,000	$ 28,000	$ 278,111,000	$ (1,740,000)	$ (176,750,000)