Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital.	Retained Earnings.	Total
Balance at Dec. 31, 2018	$ 401	$ 150,926	$ (10,218)	$ 141,109
Stock-based compensation	7	887		894
Net income (loss)			6,883	6,883
Balance at Mar. 31, 2019	408	151,813	(3,335)	148,886
Balance at Dec. 31, 2018	401	150,926	(10,218)	141,109
Net income (loss)				23,046
Balance at Sep. 30, 2019	409	153,976	12,828	167,213
Balance at Mar. 31, 2019	408	151,813	(3,335)	148,886
Stock-based compensation	1	1,059		1,060
Net income (loss)			10,613	10,613
Balance at Jun. 30, 2019	409	152,872	7,278	160,559
Stock-based compensation		1,104		1,104
Net income (loss)			5,550	5,550
Balance at Sep. 30, 2019	409	153,976	12,828	167,213
Balance at Dec. 31, 2019	410	154,957	14,716	170,083
Stock-based compensation	17	906		923
Net income (loss)			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 (loss)				(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 (loss)			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 (loss)			(4,776)	(4,776)
Balance at Sep. 30, 2020	$ 427	$ 157,866	$ 14,554	$ 172,847