CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		77,456,180
Beginning balance (in shares)		77,464,781
Beginning balance at Dec. 31, 2018	$ 44,207	$ 77	$ 230,154	$ (186,024)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(6,480)			(6,480)
Share-based compensation	326		326
Sales of common stock under 2014 ESPP (in shares)		8,601
Sales of common stock under 2014 ESPP	7		7
Ending balance (in shares) at Mar. 31, 2019		77,464,781
Ending balance at Mar. 31, 2019	38,060	$ 77	230,487	(192,504)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		77,464,781
Beginning balance (in shares)		106,801,409
Beginning balance (in shares)		109,991,553
Beginning balance at Dec. 31, 2019	(26,700)	$ 107	266,717	(293,524)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	41,564			41,564
Share-based compensation	407		407
Sales of common stock under 2014 ESPP (in shares)		2,785
Sales of common stock under 2014 ESPP	1		1
Issuance of common stock under ATM offering, net of issuance costs of $xxx (in shares)		3,187,359
Issuance of common stock under ATM Offering, net of issuance costs of $98	3,179	$ 3	3,176
Ending balance (in shares) at Mar. 31, 2020		109,991,553
Ending balance at Mar. 31, 2020	$ 18,451	$ 110	$ 270,301	$ (251,960)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		109,991,553