EARNINGS PER SHARE - Earnings per Share (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 2,374,468	$ 1,680,242	$ 2,808,643	$ 2,551,010	$ 1,878,703	$ 1,551,671	$ 6,863,353	$ 5,981,384
Less dividends:
Common stock	2,245,310	2,245,309	2,244,904	2,120,188	1,870,754	1,870,416	6,735,523	5,861,358
Preferred stock	1,198,166	$ 725,667	$ 3,708	3,792	$ 3,750	$ 3,750	1,927,542	11,292
Dividends	3,443,476			2,123,980			8,663,065	5,872,650
Undistributed earnings (deficit)	$ (1,069,008)			$ 427,030			$ (1,799,712)	$ 108,734
Total (in dollars per share)	$ 0.05			$ 0.10			$ 0.20	$ 0.24
Common Stock
Less dividends:
Distributed earnings (in dollars per share)	0.09			0.09			0.27	0.24
Undistributed earnings (deficit) (in dollars per share)	(0.04)			0.01			(0.07)	0
Total (in dollars per share)	0.05			0.10			0.20	0.24
Unvested Share-Based Payment Awards
Less dividends:
Distributed earnings (in dollars per share)	0.09			0.09			0.27	0.24
Undistributed earnings (deficit) (in dollars per share)	0			0.01			0	0
Total (in dollars per share)	$ 0.09			$ 0.10			$ 0.27	$ 0.24