Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2019	4,644,522
Balance at Dec. 31, 2019	$ 46,445	$ 22,733,933	$ 26,635,732	$ 49,416,110
Stock-based compensation	$ 0	271,631	0	271,631
401(K) stock match (in shares)	28,154
401(K) stock match	$ 282	293,693	0	293,975
Net income	$ 0	0	923,036	923,036
Exercise of stock options (in shares)	24,250
Exercise of stock options	$ 242	200,548	0	200,790
Dividend distribution	$ 0	0	(4,148)	(4,148)
Issuance of deferred stock awards (in shares)	27,917
Issuance of deferred stock awards	$ 279	(72,659)	0	(72,380)
Shares issued under Employee Stock Purchase Plan (in shares)	3,902
Shares issued under Employee Stock Purchase Plan	$ 39	36,246	0	36,285
Other share retirements (in shares)	(9,920)
Other share retirements	$ (99)	(44,587)	(79,512)	(124,198)
Balance (in shares) at Sep. 30, 2020	4,718,825
Balance at Sep. 30, 2020	$ 47,188	23,418,805	27,475,108	50,941,101
Balance (in shares) at Jun. 30, 2020	4,706,814
Balance at Jun. 30, 2020	$ 47,068	23,096,660	25,626,591	48,770,319
Stock-based compensation	$ 0	203,966	0	203,966
401(K) stock match (in shares)	9,657
401(K) stock match	$ 97	118,202	0	118,299
Net income	0	0	1,849,012	1,849,012
Dividend distribution	$ 0	0	(495)	(495)
Issuance of deferred stock awards (in shares)	2,354
Issuance of deferred stock awards	$ 23	(23)	0	0
Balance (in shares) at Sep. 30, 2020	4,718,825
Balance at Sep. 30, 2020	$ 47,188	23,418,805	27,475,108	50,941,101
Balance (in shares) at Dec. 31, 2020	4,748,012
Balance at Dec. 31, 2020	$ 47,480	23,631,618	27,614,087	51,293,185
Stock-based compensation	$ 0	400,215	0	400,215
401(K) stock match (in shares)	24,700
401(K) stock match	$ 247	396,480	0	396,727
Net income	$ 0	0	5,177,975	$ 5,177,975
Exercise of stock options (in shares)	3,654			3,654
Exercise of stock options	$ 36	48,562	0	$ 48,598
Dividend distribution	$ 0	0	(1,706)	(1,706)
Issuance of deferred stock awards (in shares)	14,597
Issuance of deferred stock awards	$ 146	(26,094)	0	(25,948)
Shares issued under Employee Stock Purchase Plan (in shares)	5,290
Shares issued under Employee Stock Purchase Plan	$ 53	53,799	0	53,852
Balance (in shares) at Sep. 30, 2021	4,796,253
Balance at Sep. 30, 2021	$ 47,962	24,504,580	32,790,356	57,342,898
Balance (in shares) at Jun. 30, 2021	4,786,173
Balance at Jun. 30, 2021	$ 47,861	24,200,481	30,032,958	54,281,300
Stock-based compensation	$ 0	130,623	0	130,623
401(K) stock match (in shares)	10,080
401(K) stock match	$ 101	173,476	0	173,577
Net income	$ 0	0	2,757,398	2,757,398
Balance (in shares) at Sep. 30, 2021	4,796,253
Balance at Sep. 30, 2021	$ 47,962	$ 24,504,580	$ 32,790,356	$ 57,342,898