SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Earnings per share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings per share
Net income	$ 10,662,125	$ 3,766,113	$ 28,618,009	$ 4,088,886
Preferred stock dividend requirements	(59,170)	(174,148)	(124,108)	(348,291)
Income applicable to common shareholders	$ 10,602,955	$ 3,591,965	$ 28,493,901	$ 3,740,595
Average common shares outstanding	34,000,771	32,789,047	33,984,271	32,735,126
Average common and common equivalent shares outstanding - assuming dilution	34,376,335	32,985,381	34,365,092	32,856,003
Basic earnings per share	$ 0.31	$ 0.11	$ 0.84	$ 0.11
Diluted earnings per share	$ 0.31	$ 0.11	$ 0.83	$ 0.11