Unaudited Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital.	Retained Earnings.	Total
Balance at Dec. 31, 2019	$ 410	$ 154,957	$ 14,716	$ 170,083
Stock-based compensation	17	906		923
Net income			1,962	1,962
Balance at Mar. 31, 2020	427	155,863	16,678	172,968
Balance at Dec. 31, 2019	410	154,957	14,716	170,083
Net income				(162)
Balance at Sep. 30, 2020	427	157,866	14,554	172,847
Balance at Mar. 31, 2020	427	155,863	16,678	172,968
Restricted stock surrendered for withholding taxes payable	(1)	(192)		(193)
Stock-based compensation		1,106		1,106
Net income			2,652	2,652
Balance at Jun. 30, 2020	426	156,777	19,330	176,533
Stock-based compensation	1	1,089		1,090
Net income			(4,776)	(4,776)
Balance at Sep. 30, 2020	427	157,866	14,554	172,847
Balance at Dec. 31, 2020	427	158,859	9,809	169,095
Stock-based compensation	15	1,040		1,055
Net income			4,143	4,143
Balance at Mar. 31, 2021	442	159,899	13,952	174,293
Balance at Dec. 31, 2020	427	158,859	9,809	169,095
Net income				21,120
Balance at Sep. 30, 2021	441	162,437	30,929	193,807
Balance at Mar. 31, 2021	442	159,899	13,952	174,293
Restricted stock surrendered for withholding taxes payable	(1)	(326)		(327)
Stock-based compensation		1,522		1,522
Net income			9,942	9,942
Balance at Jun. 30, 2021	441	161,095	23,894	185,430
Stock-based compensation		1,342		1,342
Net income			7,035	7,035
Balance at Sep. 30, 2021	$ 441	$ 162,437	$ 30,929	$ 193,807