Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2019		7,688,958
Beginning balance at Dec. 31, 2019	$ 46,870	$ 1	$ 56,557	$ (9,688)
Stock-based compensation	295		295
Shares issued related to vested restricted stock units (in shares)		104,905
Shares issued related to vested restricted stock units	0
Net income	(52)			(52)
Ending balance (in shares) at Mar. 31, 2020		7,793,863
Ending balance at Mar. 31, 2020	47,113	$ 1	56,852	(9,740)
Beginning balance (in shares) at Dec. 31, 2019		7,688,958
Beginning balance at Dec. 31, 2019	46,870	$ 1	56,557	(9,688)
Net income	5,420
Ending balance (in shares) at Sep. 30, 2020		7,894,202
Ending balance at Sep. 30, 2020	53,127	$ 1	57,394	(4,268)
Beginning balance (in shares) at Mar. 31, 2020		7,793,863
Beginning balance at Mar. 31, 2020	47,113	$ 1	56,852	(9,740)
Stock-based compensation	140		140
Shares issued related to vested restricted stock units (in shares)		59,514
Shares issued related to vested restricted stock units	0
Net income	2,947			2,947
Ending balance (in shares) at Jun. 30, 2020		7,853,377
Ending balance at Jun. 30, 2020	50,200	$ 1	56,992	(6,793)
Stock-based compensation	304		304
Shares issued related to vested restricted stock units (in shares)		10,000
Shares issued related to vested restricted stock units	0
Stock issued related to employee stock purchase plan (in shares)		30,825
Shares issued related to employee stock purchase plan	98		98
Net income	2,525			2,525
Ending balance (in shares) at Sep. 30, 2020		7,894,202
Ending balance at Sep. 30, 2020	53,127	$ 1	57,394	(4,268)
Beginning balance (in shares) at Dec. 31, 2020		7,926,137
Beginning balance at Dec. 31, 2020	53,732	$ 1	57,612	(3,881)
Stock-based compensation	677		677
Shares issued related to vested restricted stock units (in shares)		89,446
Shares issued related to vested restricted stock units	0
Tax withholding related to vested restricted stock units	(183)		(183)
Stock issued related to employee stock purchase plan (in shares)		8,928
Shares issued related to employee stock purchase plan	92		92
Shares issued related to exercise of warrants (in shares)		172,869
Shares issued related to the exercise of warrants	1,989		1,989
Shares issued related to offering (in shares)		2,051,025
Shares issued related to sale of common stock	22,773		22,773
Net income	(2,282)			(2,282)
Ending balance (in shares) at Mar. 31, 2021		10,248,405
Ending balance at Mar. 31, 2021	76,798	$ 1	82,960	(6,163)
Beginning balance (in shares) at Dec. 31, 2020		7,926,137
Beginning balance at Dec. 31, 2020	53,732	$ 1	57,612	(3,881)
Net income	2,436
Ending balance (in shares) at Sep. 30, 2021		10,274,242
Ending balance at Sep. 30, 2021	82,975	$ 1	84,419	(1,445)
Beginning balance (in shares) at Mar. 31, 2021		10,248,405
Beginning balance at Mar. 31, 2021	76,798	$ 1	82,960	(6,163)
Stock-based compensation	636		636
Shares issued related to vested restricted stock units (in shares)		3,291
Shares issued related to vested restricted stock units	0
Tax withholding related to vested restricted stock units	(7)		(7)
Net income	732			732
Ending balance (in shares) at Jun. 30, 2021		10,251,696
Ending balance at Jun. 30, 2021	78,159	$ 1	83,589	(5,431)
Stock-based compensation	703		703
Shares issued related to vested restricted stock units (in shares)		6,401
Shares issued related to vested restricted stock units	0
Stock issued related to employee stock purchase plan (in shares)		16,140
Shares issued related to employee stock purchase plan	127		127
Shares issued related to exercise of warrants (in shares)		5
Shares issued related to the exercise of warrants	0
Net income	3,986			3,986
Ending balance (in shares) at Sep. 30, 2021		10,274,242
Ending balance at Sep. 30, 2021	$ 82,975	$ 1	$ 84,419	$ (1,445)