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	205,300				205,380
Net income				2,780,411		2,780,411
Translation adjustment					1,028,599	1,028,599
Balance (in shares) at Sep. 30, 2017	9,270,862
Balance at Sep. 30, 2017	$ 27,153	6,797,052	(10,278,584)	62,249,904	(864,530)	57,930,995
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	76,407				76,447
Net income				2,592,177		2,592,177
Translation adjustment					(154,642)	(154,642)
Cumulative effect of accounting change (see Note 1) at Dec. 31, 2017				(168,311)		(168,311)
Purchase of treasury stock (in shares)	(133,302)
Purchase of treasury stock			(995,238)			(995,238)
Balance (in shares) at Sep. 30, 2018	9,154,208
Balance at Sep. 30, 2018	$ 27,193	$ 6,907,678	$ (11,273,822)	$ 66,345,110	$ (1,116,745)	$ 60,889,414