Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Dec. 31, 2015		57,374,907	(821,756.000)
Beginning Balance at Dec. 31, 2015	$ 165,305	$ 57	$ (1)	$ 286,856	$ (119,071)	$ (2,536)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options (in shares)	325,000	324,502
Common stock issued upon exercise of stock options	$ 1,806			1,806
Common stock issued upon vesting of restricted stock units (in shares)		393,504
Common stock issued upon vesting of restricted stock units	1	$ 1
Stock-based compensation	9,736			9,736
Common stock issued under Employee Stock Purchase Plan (in shares)		183,534
Common stock issued under Employee Stock Purchase Plan	1,092			1,092
Common stock repurchase (in shares)			(1,518,349)
Common stock repurchase	(9,967)		$ (1)	(9,966)
Net loss	(25,873)				(25,873)
Other comprehensive income (loss)	(3,624)					(3,624)
Ending Balance (in shares) at Dec. 31, 2016		58,276,447	(2,340,105)
Ending Balance at Dec. 31, 2016	$ 138,476	$ 58	$ (2)	289,524	(144,944)	(6,160)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options (in shares)	854,000	853,885
Common stock issued upon exercise of stock options	$ 7,491	$ 1		7,490
Common stock issued upon vesting of restricted stock units (in shares)		363,429
Common stock issued upon vesting of restricted stock units	1	$ 1
Stock-based compensation	8,944			8,944
Common stock issued under Employee Stock Purchase Plan (in shares)		170,208
Common stock issued under Employee Stock Purchase Plan	1,459			1,459
Common stock repurchase (in shares)			(247,430)
Common stock repurchase	(1,742)		$ (1)	(1,741)
Net loss	(18,191)				(18,191)
Other comprehensive income (loss)	3,625					3,625
Ending Balance (in shares) at Dec. 31, 2017		59,663,969	(2,587,535)
Ending Balance at Dec. 31, 2017	$ 140,063	$ 60	$ (3)	305,676	(163,135)	(2,535)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options (in shares)	3,120,000	3,120,404
Common stock issued upon exercise of stock options	$ 32,791	$ 3		32,788
Common stock issued upon vesting of restricted stock units (in shares)		361,539
Common stock issued upon vesting of restricted stock units	1	$ 1
Stock-based compensation	14,841			14,841
Common stock issued under Employee Stock Purchase Plan (in shares)		150,989
Common stock issued under Employee Stock Purchase Plan	2,480			2,480
Common stock repurchase (in shares)			(93,750)
Common stock repurchase	(1,345)		$ 0	(1,345)
ASC 606 prior period adjustment	676
Issuance of common stock in connection with acquisitions (in shares)		379,328
Issuance of common stock in connection with acquisitions	8,150			8,150
Net loss	(25,032)
Other comprehensive income (loss)	(1,896)					(1,896)
Ending Balance (in shares) at Dec. 31, 2018		63,676,229	(2,681,285)
Ending Balance at Dec. 31, 2018	$ 170,729	$ 64	$ (3)	$ 362,590	$ (187,491)	$ (4,431)