Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Common stock	Additional paid-in capital	Accumulated other comprehensive loss [Member]	Accumulated deficit	Total
Beginning Balance at Dec. 31, 2018	$ 22	$ 216,931		$ (175,888)	$ 41,065
Beginning balance (in shares) at Dec. 31, 2018	22,369,036
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options and vesting restricted stock	$ 1	502			503
Exercise of common stock options and vesting restricted stock (in shares)	102,361
ESPP stock purchase		328			328
ESPP stock purchase (in shares)	20,050
Stock-based compensation expense		1,284			1,284
Net loss				(9,405)	(9,405)
Ending Balance at Mar. 31, 2019	$ 23	219,045		(184,853)	34,215
Ending Balance (in shares) at Mar. 31, 2019	22,491,447
Increase (Decrease) in Stockholders' Equity
Cumulative-effect adjustment for the adoption of ASC 606				440	440
Beginning Balance at Dec. 31, 2019	$ 28	345,027	$ (153)	(216,244)	128,658
Beginning balance (in shares) at Dec. 31, 2019	28,112,201
Increase (Decrease) in Stockholders' Equity
Exercise of common stock options and vesting restricted stock		496			496
Exercise of common stock options and vesting restricted stock (in shares)	108,548
ESPP stock purchase		440			440
ESPP stock purchase (in shares)	22,693
Stock-based compensation expense		2,109			2,109
Cumulative translation adjustment			(1,047)		(1,047)
Net loss				(11,610)	(11,610)
Ending Balance at Mar. 31, 2020	$ 28	$ 348,072	$ (1,200)	$ (227,854)	$ 119,046
Ending Balance (in shares) at Mar. 31, 2020	28,243,442