Condensed consolidated Statements of Stockholders' Equity (unaudited) - USD ($)	Common Stock [Member]	Additional Paid in Capital [Member]	Retained Earning [Member]	Treasury Stock [Member]	Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to adoption of ASC606 | ASU 2014-09 [Member]	$ 0	$ 0	$ 10,184,335	$ 0	$ 10,184,335
Balances at Dec. 31, 2017	$ 7,600	33,468,323	41,939,115	(7,898,200)	67,516,838
Balances (in shares) at Dec. 31, 2017	7,600,167
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon stock option exercise	$ 55	859,995	0	0	860,050
Issuance of common stock upon stock option exercise (in shares)	55,000
Stock compensation expense	$ 0	96,314	0	0	96,314
Net income	0	0	8,826,535	0	8,826,535
Balances at Jun. 30, 2018	$ 7,655	34,424,632	60,949,985	(7,898,200)	87,484,072
Balances (in shares) at Jun. 30, 2018	7,655,167
Balances at Mar. 31, 2018	$ 7,610	33,633,225	56,102,054	(7,898,200)	81,844,689
Balances (in shares) at Mar. 31, 2018	7,610,167
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon stock option exercise	$ 45	727,605	0	0	727,650
Issuance of common stock upon stock option exercise (in shares)	45,000
Stock compensation expense	$ 0	63,802	0	0	63,802
Net income	0	0	4,847,931	0	4,847,931
Balances at Jun. 30, 2018	$ 7,655	34,424,632	60,949,985	(7,898,200)	87,484,072
Balances (in shares) at Jun. 30, 2018	7,655,167
Balances at Dec. 31, 2018	$ 7,738	36,302,446	72,176,719	(10,898,383)	$ 97,588,520
Balances (in shares) at Dec. 31, 2018	7,738,167				7,275,902
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon stock option exercise	$ 58	1,736,888	0	0	$ 1,736,946
Issuance of common stock upon stock option exercise (in shares)	58,063
Stock compensation expense	$ 0	260,466	0	0	260,466
Repurchases of common stock	0	0	0	(118,566)	(118,566)
Net income	0	0	10,843,055	0	10,843,055
Balances at Jun. 30, 2019	$ 7,796	38,299,800	83,019,774	(11,016,949)	$ 110,310,421
Balances (in shares) at Jun. 30, 2019	7,796,230				7,331,917
Balances at Mar. 31, 2019	$ 7,740	36,502,652	76,593,314	(10,898,383)	$ 102,205,323
Balances (in shares) at Mar. 31, 2019	7,740,167
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon stock option exercise	$ 56	1,678,470	0	0	1,678,526
Issuance of common stock upon stock option exercise (in shares)	56,063
Stock compensation expense	$ 0	118,678	0	0	118,678
Repurchases of common stock	0	0	0	(118,566)	(118,566)
Net income	0	0	6,426,460	0	6,426,460
Balances at Jun. 30, 2019	$ 7,796	$ 38,299,800	$ 83,019,774	$ (11,016,949)	$ 110,310,421
Balances (in shares) at Jun. 30, 2019	7,796,230				7,331,917