Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income/(Loss)	Accumulated Deficit	Cumulative Effect Adjustment	Cumulative Effect Adjustment Accumulated Deficit
Common stock, beginning balance (in shares) at Dec. 31, 2018		43,535
Beginning balance at Dec. 31, 2018	$ 158,900	$ 4	$ 331,355	$ (37)	$ (172,422)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	9,154		9,154
Exercise of stock options (in shares)		272
Exercise of stock options	3,741		3,741
Shares acquired to settle the exercise of stock options (in shares)		(3)
Shares acquired to settle the exercise of stock options	(217)		(217)
Shares issued for the vesting of restricted stock awards (in shares)		312
Shares issued for the vesting of restricted stock awards	0
Other comprehensive loss	126			126
Net loss	(19,311)				(19,311)
Common stock, ending balance (in shares) at Mar. 31, 2019		44,116
Ending balance at Mar. 31, 2019	$ 152,393	$ 4	344,033	89	(191,733)
Common stock, beginning balance (in shares) at Dec. 31, 2019	48,386	48,386
Beginning balance at Dec. 31, 2019	$ 379,412	$ 5	622,692	14	(243,299)	$ (268)	$ (268)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	14,866		14,866
Exercise of stock options (in shares)		136
Exercise of stock options	1,449		1,449
Shares acquired to settle the exercise of stock options (in shares)		(3)
Shares acquired to settle the exercise of stock options	(264)		(264)
Shares issued for the vesting of restricted stock awards (in shares)		444
Shares issued for the vesting of restricted stock awards	0
Other comprehensive loss	(177)			(177)
Net loss	$ (34,108)				(34,108)
Common stock, ending balance (in shares) at Mar. 31, 2020	48,963	48,963
Ending balance at Mar. 31, 2020	$ 360,910	$ 5	$ 638,743	$ (163)	$ (277,675)