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, 2012	$ 6,625	$ 20,688,706	$ (310,929)	$ (2,926,156)	$ 17,458,346
Balances (in shares) at Dec. 31, 2012	6,625,168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock option plans	$ 30	29,970	0	0	30,000
Issuance of common stock under stock option plans (in shares)	30,000
Effect of canceled of stock options	$ 0	(75,928)	0	0	(75,928)
Stock compensation expense	0	111,636	0	0	111,636
Repurchases of common stock	0	0	0	(674,874)	(674,874)
Excess tax benefits from share-based payment arrangements	0	197,412	0	0	197,412
Net income	0	0	5,285,847	0	5,285,847
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 under stock option plans	$ 407	2,146,414	0	0	2,146,821
Issuance of common stock under stock option plans (in shares)	407,042
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				6,730,622
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock option plans	$ 228	2,823,755	0	0	$ 2,823,983
Issuance of common stock under stock option plans (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