Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Common Stock	Common Stock Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent	$ 52,137	$ 23	$ 257,955	$ (205,825)	$ (16)
Accounting Standards Codification 326 cumulative effect adjustment upon adoption	52,137	$ 23	257,955	(205,825)	(16)
Beginning balance (in shares) at Dec. 31, 2018		24,368,073
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee equity incentive plans, net (in shares)		260,570
Issuance of common stock in connection with employee equity incentive plans, net		$ 1				$ 2,121	$ 2,120
Tax withholding upon vesting of restricted stock awards	(3,259)			0	0
Stock-based compensation expense	4,856		4,856	0	0
Net loss	(8,250)		0	(8,250)	0
Net change in unrealized gain on investments	$ 43		0	0	43
Ending balance (in shares) at Mar. 31, 2019		24,628,643
Beginning balance (in shares) at Dec. 31, 2018		24,368,073
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with employee equity incentive plans, net (in shares)	540,307
Ending balance (in shares) at Dec. 31, 2019		26,682,720
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent	$ 47,648	$ 24	261,672	(214,075)	27
Accounting Standards Codification 326 cumulative effect adjustment upon adoption	47,648	24	261,672	(214,075)	27
Stockholders' Equity Attributable to Parent	135,409	25	395,695	(260,393)	82
Accounting Standards Codification 326 cumulative effect adjustment upon adoption	$ 135,409	$ 25	395,695	(260,393)	82
Issuance of common stock in connection with employee equity incentive plans, net (in shares)	264,800	344,255
Issuance of common stock in connection with employee equity incentive plans, net		$ 0				$ 2,969	$ 2,969
Tax withholding upon vesting of restricted stock awards	$ (4,462)			0	0
Stock-based compensation expense	305			0	0
Net loss	(9,065)		0	(9,065)	0
Net change in unrealized gain on investments	282		0	0	282
Ending balance (in shares) at Mar. 31, 2020		27,026,975
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent	124,977	$ 25	394,507	(269,919)	364
Accounting Standards Codification 326 cumulative effect adjustment upon adoption	$ 124,977	$ 25	$ 394,507	$ (269,919)	$ 364