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	9,266,496
Balance at Dec. 31, 2016	$ 27,142	$ 6,368,279	$ (10,278,584)	$ 59,469,493	$ (1,893,129)	$ 53,693,201
Stock-based compensation (in shares)	9,005
Stock-based compensation	$ 22	44,772				44,794
Net income				1,231,265		1,231,265
Translation adjustment					356,340	356,340
Balance (in shares) at Mar. 31, 2017	9,275,501
Balance at Mar. 31, 2017	$ 27,164	6,413,051	(10,278,584)	60,700,758	(1,536,789)	55,325,600
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
Cumulative effect of accounting change (see Note 1) at Dec. 31, 2017				(168,311)		(168,311)
Stock-based compensation (in shares)	16,648
Stock-based compensation	$ 40	28,929				28,969
Purchase of treasury stock (in shares)	(72,400)
Purchase of treasury stock			(540,940)			(540,940)
Net income				1,273,619		1,273,619
Translation adjustment					21,791	21,791
Balance (in shares) at Mar. 31, 2018	9,215,110
Balance at Mar. 31, 2018	$ 27,193	$ 6,860,200	$ (10,819,524)	$ 65,026,552	$ (940,312)	$ 60,154,109