CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Total	Redeemable Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Cumulative translation adjustment [Member]	Non-controlling interests [Member]
Balance at Dec. 31, 2014	$ 144,082,664	$ 22,104	$ 8,829,539	$ 83,779,292	$ 49,000,621	$ (482,388)	$ 2,933,496
Balance (in shares) at Dec. 31, 2014		36,840	14,715,899
Issue of share capital	143,218	$ 5,169	$ 6,308	131,741	0	0	0
Issue of share capital (in shares)		8,615	10,514
Conversion of preferred stock	0	$ (4,317)	$ 4,317	0	0	0	0
Conversion of preferred stock (in shares)		(7,195)	7,195
Buyback of preferred stock	(6,014)	$ (449)	$ 0	(5,565)	0	0	0
Buyback of preferred stock (in shares)		(748)	0
Net income	7,925,494	$ 0	$ 0	0	7,518,701	0	406,793
Exercise of options	456,763	$ 775	$ 28,557	427,431	0	0	0
Exercise of options (in shares)		1,292	47,593
Dividends declared	(4,617,810)	$ 0	$ 0	0	(4,435,147)	0	(182,663)
Foreign currency translation adjustment	(53,660)	0	0	0	0	(50,977)	(2,683)
Stock-based compensation	264,450	0	0	264,450	0	0	0
Balance at Dec. 31, 2015	148,195,105	$ 23,282	$ 8,868,721	84,597,349	52,084,175	(533,365)	3,154,943
Balance (in shares) at Dec. 31, 2015		38,804	14,781,201
Issue of share capital	179,573	$ 5,053	$ 15,094	159,426	0	0	0
Issue of share capital (in shares)		8,421	25,156
Conversion of preferred stock	0	$ (6,935)	$ 6,935	0	0	0	0
Conversion of preferred stock (in shares)		(11,558)	11,558
Buyback of preferred stock	(14,054)	$ (1,053)	$ 0	(13,001)	0	0	0
Buyback of preferred stock (in shares)		(1,755)	0
Net income	2,777,313	$ 0	$ 0	0	3,960,501	0	(1,183,188)
Exercise of options	568,849	$ 788	$ 32,248	535,813	0	0	0
Exercise of options (in shares)		1,313	53,749
Dividends declared	(4,638,002)	$ 0	$ 0	0	(4,455,339)	0	(182,663)
Foreign currency translation adjustment	(17,042)	0	0	0	0	(16,190)	(852)
Aerex non-controlling interest at acquisition date	6,712,184	0	0	0	0		6,712,184
Stock-based compensation	341,446	0	0	341,446	0	0	0
Balance at Dec. 31, 2016	154,105,372	$ 21,135	$ 8,922,998	85,621,033	51,589,337	(549,555)	8,500,424
Balance (in shares) at Dec. 31, 2016		35,225	14,871,664
Issue of share capital	210,151	$ 5,665	$ 20,995	183,491	0	0	0
Issue of share capital (in shares)		9,441	34,991
Conversion of preferred stock	0	$ (7,328)	$ 7,328	0	0	0	0
Conversion of preferred stock (in shares)		(12,214)	12,214
Buyback of preferred stock	(9,719)	$ (656)	$ 0	(9,063)	0	0	0
Buyback of preferred stock (in shares)		(1,093)	0
Net income	5,732,573	$ 0	$ 0	0	6,144,062	0	(411,489)
Exercise of options	17,777	$ 1,277	$ 0	16,500	0	0	0
Exercise of options (in shares)		2,129	0
Dividends declared	(4,628,203)	$ 0	$ 0	0	(4,628,203)	0	0
Foreign currency translation adjustment	0
Stock-based compensation	593,426	0	0	593,426	0	0	0
Balance at Dec. 31, 2017	$ 156,021,377	$ 20,093	$ 8,951,321	$ 86,405,387	$ 53,105,196	$ (549,555)	$ 8,088,935
Balance (in shares) at Dec. 31, 2017		33,488	14,918,869