CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	ASU 2016-13 Adjustment Accumulated Deficit
Beginning balance at Dec. 31, 2018	$ 170,729	$ 64	$ (3)	$ 362,590	$ (187,491)	$ (4,431)
Beginning balance (in shares) at Dec. 31, 2018		63,676,046	2,681,285
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options	9,081	$ 1		9,080
Common stock issued upon exercise of stock options (in shares)		889,546
Common stock issued upon vesting of restricted stock units	0	$ 0
Common stock issued upon vesting of restricted stock units (in shares)		754,174
Common stock as earnout payment in connection with AdvantageTec Inc.	0
Stock-based compensation	11,689			11,689
Bonus cash payment settled in shares of the Company's common stock	0
Common stock issued under Employee Stock Purchase Plan	1,873			1,873
Common stock issued under Employee Stock Purchase Plan (in shares)		79,032
Common stock repurchase	(709)			(709)
Common stock repurchase (in shares)			(23,421)
Equity component of convertible senior notes	52,900			52,900
Equity component of convertible senior notes issuance costs	(1,986)			(1,986)
Purchase of capped call option	(23,184)			(23,184)
Net loss	(42,877)				(42,877)
Other comprehensive loss	(200)					(200)
Ending balance at Jun. 30, 2019	177,316	$ 65	$ (3)	412,253	(230,368)	(4,631)
Ending balance (in shares) at Jun. 30, 2019		65,398,798	2,704,706
Beginning balance at Dec. 31, 2018	170,729	$ 64	$ (3)	362,590	(187,491)	(4,431)
Beginning balance (in shares) at Dec. 31, 2018		63,676,046	2,681,285
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Purchase of capped call option	(23,200)
Ending balance at Dec. 31, 2019	$ 148,535	$ 67	$ (3)	436,557	(283,562)	(4,524)	$ (729)
Ending balance (in shares) at Dec. 31, 2019	66,543,073	66,543,073	2,709,830
Beginning balance at Mar. 31, 2019	$ 191,039	$ 65	$ (3)	401,996	(206,381)	(4,638)
Beginning balance (in shares) at Mar. 31, 2019		64,747,798	2,704,706
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options	2,604			2,604
Common stock issued upon exercise of stock options (in shares)		263,068
Common stock issued upon vesting of restricted stock units	0
Common stock issued upon vesting of restricted stock units (in shares)		339,249
Stock-based compensation	6,501			6,501
Common stock issued under Employee Stock Purchase Plan	1,152			1,152
Common stock issued under Employee Stock Purchase Plan (in shares)		48,683
Net loss	(23,987)				(23,987)
Other comprehensive loss	7					7
Ending balance at Jun. 30, 2019	177,316	$ 65	$ (3)	412,253	(230,368)	(4,631)
Ending balance (in shares) at Jun. 30, 2019		65,398,798	2,704,706
Beginning balance at Dec. 31, 2019	$ 148,535	$ 67	$ (3)	436,557	(283,562)	(4,524)	$ (729)
Beginning balance (in shares) at Dec. 31, 2019	66,543,073	66,543,073	2,709,830
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options	$ 7,034			7,034
Common stock issued upon exercise of stock options (in shares)	603,000	602,658
Common stock issued upon vesting of restricted stock units	$ 1	$ 1
Common stock issued upon vesting of restricted stock units (in shares)		501,804
Common stock as earnout payment in connection with AdvantageTec Inc.	294	$ 1		293
Common stock as earnout payment in connection with AdvantageTec Inc. (in shares)		11,508
Stock-based compensation	16,952			16,952
Bonus cash payment settled in shares of the Company's common stock	24,656			24,656
Bonus cash payment settled in shares of the Company's common stock (in shares)		991,905
Common stock issued under Employee Stock Purchase Plan	2,737			2,737
Common stock issued under Employee Stock Purchase Plan (in shares)		80,529
Common stock repurchase	0
Equity component of convertible senior notes	0
Equity component of convertible senior notes issuance costs	0
Purchase of capped call option	0
Net loss	(55,628)				(55,628)
Other comprehensive loss	(538)					(538)
Ending balance at Jun. 30, 2020	$ 143,314	$ 69	$ (3)	488,229	(339,919)	(5,062)
Ending balance (in shares) at Jun. 30, 2020	68,731,477	68,731,477	2,709,830
Beginning balance at Mar. 31, 2020	$ 146,386	$ 68	$ (3)	474,606	(321,292)	(6,993)
Beginning balance (in shares) at Mar. 31, 2020		68,000,209	2,709,830
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options	5,079			5,079
Common stock issued upon exercise of stock options (in shares)		403,443
Common stock issued upon vesting of restricted stock units	1	$ 1
Common stock issued upon vesting of restricted stock units (in shares)		298,114
Stock-based compensation	7,433			7,433
Common stock issued under Employee Stock Purchase Plan	1,111			1,111
Common stock issued under Employee Stock Purchase Plan (in shares)		29,711
Net loss	(18,627)				(18,627)
Other comprehensive loss	1,931					1,931
Ending balance at Jun. 30, 2020	$ 143,314	$ 69	$ (3)	$ 488,229	$ (339,919)	$ (5,062)
Ending balance (in shares) at Jun. 30, 2020	68,731,477	68,731,477	2,709,830