CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Treasury Stock	Total
Balance at Dec. 31, 2018	$ 36	$ 378,352	$ 738	$ (205,134)	$ (132)	$ 173,860
Balance (in shares) at Dec. 31, 2018	36,135				(28)
Stockholders' Deficit
Common stock issued under stock plans		5,406				5,406
Common stock issued under stock plans (in shares)	226
Stock-based compensation		7,129				7,129
Other comprehensive income (loss)			436			436
Net income (loss)				(1,342)		(1,342)
Balance at Mar. 31, 2019	$ 36	390,887	1,174	(206,476)	$ (132)	185,489
Balance (in shares) at Mar. 31, 2019	36,361				(28)
Balance at Dec. 31, 2019	$ 44	861,740	1,330	(189,710)	$ (132)	$ 673,272
Balance (in shares) at Dec. 31, 2019	43,530				(28)	43,502
Stockholders' Deficit
Common stock issued under stock plans		4,220				$ 4,220
Common stock issued under stock plans (in shares)	589
Stock-based compensation		17,176				17,176
Other comprehensive income (loss)			689			689
Net income (loss)				(54,058)		(54,058)
Balance at Mar. 31, 2020	$ 44	$ 883,136	$ 2,019	$ (243,768)	$ (132)	$ 641,299
Balance (in shares) at Mar. 31, 2020	44,119				(28)	44,091