Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital.	Retained Earnings.	Total
Balance at Dec. 31, 2017	$ 396	$ 148,293	$ (35,292)	$ 113,397
Stock-based compensation	5	2,633		2,638
Net income (loss)			25,074	25,074
Balance at Dec. 31, 2018	401	150,926	(10,218)	141,109
Restricted stock surrendered for withholding taxes payable		(20)		(20)
Stock-based compensation	9	4,051		4,060
Net income (loss)			24,934	24,934
Balance at Dec. 31, 2019	410	154,957	14,716	170,083
Restricted stock surrendered for withholding taxes payable	(1)	(220)		(221)
Stock-based compensation	18	4,122		4,140
Net income (loss)			(4,907)	(4,907)
Balance at Dec. 31, 2020	$ 427	$ 158,859	$ 9,809	$ 169,095