CONSOLIDATED STATEMENT OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Stockholders' Equity, Beginning Balance at Dec. 31, 2018	$ 486,365	$ 27	$ 633,251	$ (223)	$ (146,690)
Stockholders' Equity, Beginning Balance (in shares) at Dec. 31, 2018		26,922,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under employee stock plans	574		574
Shares issued under employee stock plans (in shares)		84,000
Stock-based compensation	2,867		2,867
Comprehensive income (loss), net	427			427
Net loss	(22,078)				(22,078)
Stockholders' Equity, Ending Balance at Mar. 31, 2019	468,155	$ 27	636,692	204	(168,768)
Stockholders' Equity, Ending Balance (in shares) at Mar. 31, 2019		27,006,000
Stockholders' Equity, Beginning Balance at Dec. 31, 2019	405,008	$ 27	648,669	338	(244,026)
Stockholders' Equity, Beginning Balance (in shares) at Dec. 31, 2019		27,255,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under employee stock plans	$ 36		36
Shares issued under employee stock plans (in shares)	22,033	22,000
Stock-based compensation	$ 2,975		2,975
Comprehensive income (loss), net	807			807
Net loss	(8,262)				(8,262)
Stockholders' Equity, Ending Balance at Mar. 31, 2020	$ 400,564	$ 27	$ 651,680	$ 1,145	$ (252,288)
Stockholders' Equity, Ending Balance (in shares) at Mar. 31, 2020		27,277,000