CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Redeemable preferred stock [Member]	Common stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Non controlling interests [Member]	Total
Balance at Dec. 31, 2019	$ 20,251	$ 9,029,765	$ 88,356,509	$ 66,352,733	$ 14,193,616	$ 177,952,874
Balance (in shares) at Dec. 31, 2019	33,751	15,049,608
Issuance of share capital	$ 0	$ 38,939	(38,939)	0	0	0
Issuance of share capital (in shares)	0	64,898
Net income	$ 0	$ 0	0	2,888,607	360,998	3,249,605
Purchase of noncontrolling interests in Aerex and PERC			(2,444,047)		(6,055,953)	(8,500,000)
Dividends declared	0	0	0	(1,289,378)	0	(1,289,378)
Stock-based compensation	0	0	161,406	0	0	161,406
Balance at Mar. 31, 2020	$ 20,251	$ 9,068,704	86,034,929	67,951,962	8,498,661	171,574,507
Balance (in shares) at Mar. 31, 2020	33,751	15,114,506
Balance at Dec. 31, 2020	$ 18,641	$ 9,086,210	86,893,486	64,910,709	8,103,503	169,012,549
Balance (in shares) at Dec. 31, 2020	31,068	15,143,683
Issuance of share capital	$ 0	$ 34,546	(34,546)	0	0	0
Issuance of share capital (in shares)	0	57,577
Conversion of preferred stock	$ (129)	$ 129
Conversion of preferred stock (in shares)	(215)	215
Buyback of preferred stock	$ (448)		(7,065)			(7,513)
Buyback of preferred stock (in shares)	(747)
Net income	$ 0	$ 0	0	988,772	128,793	1,117,565
Dividends declared	0	0	0	(1,296,197)	(649,880)	(1,946,077)
Stock-based compensation	0	0	176,210	0	0	176,210
Balance at Mar. 31, 2021	$ 18,064	$ 9,120,885	$ 87,028,085	$ 64,603,284	$ 7,582,416	$ 168,352,734
Balance (in shares) at Mar. 31, 2021	30,106	15,201,475