Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock [Member]	Additional Paid in Capital [Member]	Retained Earning [Member]	Treasury Stock [Member]	Total
Balances at Dec. 31, 2013	$ 6,655	$ 20,951,796	$ 4,975,018	$ (3,601,030)	$ 22,332,439
Balances (in shares) at Dec. 31, 2013	6,655,168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon stock option exercise	$ 407	2,146,414	0	0	2,146,821
Issuance of common stock upon stock option exercise (in shares)	407,041
Stock compensation expense	$ 0	21,416	0	0	21,416
Repurchases of common stock	0	0	0	(829,613)	(829,613)
Excess tax benefits from share-based payment arrangements	0	1,939,832	0	0	1,939,832
Net income	0	0	4,645,960	0	4,645,960
Balances at Dec. 31, 2014	$ 7,062	25,059,458	9,620,978	(4,430,643)	30,256,855
Balances (in shares) at Dec. 31, 2014	7,062,209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon stock option exercise	$ 228	2,823,755	0	0	2,823,983
Issuance of common stock upon stock option exercise (in shares)	227,958
Stock compensation expense	$ 0	105,782	0	0	105,782
Repurchases of common stock	0	0	0	(1,802,466)	(1,802,466)
Excess tax benefits from share-based payment arrangements	0	3,808,423	0	0	3,808,423
Net income	0	0	9,617,632	0	9,617,632
Balances at Dec. 31, 2015	$ 7,290	31,797,418	19,238,610	(6,233,109)	$ 44,810,209
Balances (in shares) at Dec. 31, 2015	7,290,167				6,918,579
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon stock option exercise	$ 265	711,135	0	0	$ 711,400
Issuance of common stock upon stock option exercise (in shares)	265,000
Stock compensation expense	$ 0	133,904	0	0	133,904
Repurchases of common stock	0	0	0	(1,048,592)	(1,048,592)
Excess tax benefits from share-based payment arrangements	0	302,783	0	0	302,783
Net income	0	0	11,372,239	0	11,372,239
Balances at Dec. 31, 2016	$ 7,555	$ 32,945,240	$ 30,610,849	$ (7,281,701)	$ 56,281,943
Balances (in shares) at Dec. 31, 2016	7,555,167				7,156,281