Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2016	9,193,162
Balance at Dec. 31, 2016	$ 26,966	$ 6,368,455	$ (10,278,584)	$ 59,469,493	$ (1,893,129)	$ 53,693,201
Exercise of stock options (in shares)	44,400
Exercise of stock options	$ 107	223,297				223,404
Stock-based compensation (in shares)	33,300
Stock-based compensation	$ 80	171,080				171,160
Net income				2,258,997		2,258,997
Translation adjustment					658,359	658,359
Balance (in shares) at Jun. 30, 2017	9,270,862
Balance at Jun. 30, 2017	$ 27,153	6,762,832	(10,278,584)	61,728,490	(1,234,770)	57,005,121
Balance (in shares) at Dec. 31, 2017	9,270,862
Balance at Dec. 31, 2017	$ 27,153	6,831,271	(10,278,584)	63,921,244	(962,103)	59,538,981
Stock-based compensation (in shares)	16,648
Stock-based compensation	$ 40	52,648				52,688
Net income				2,713,711		2,713,711
Translation adjustment					(272,807)	(272,807)
Balance (in shares) at Jun. 30, 2018	9,154,215
Balance at Jun. 30, 2018	$ 27,193	$ 6,883,919	(11,273,770)	66,466,644	$ (1,234,910)	60,869,076
Cumulative effect of accounting change (see Note 1) at Dec. 31, 2017				$ (168,311)		(168,311)
Purchase of treasury stock (in shares)	(133,295)
Purchase of treasury stock			$ (995,186)			$ (995,186)