STOCK-BASED COMPENSATION - Stock options (Details) - Stock Options - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Option Awards
Balance at the beginning of the period	2,169,243
Granted		583,565	289,890
Forfeited	(20,948)
Expired	(41,892)
Balance at the end of the period	2,106,403	2,169,243
Exercisable at end of the period	1,632,958
Unrecognized cost inclusive of directors' awards	$ 805,000
Weighted average remaining recognition period (years)	1 year 1 month 13 days
Weighted Average Exercise Price
Balance at the beginning of the period	$ 9.87
Forfeited	10.23
Expired	10.23
Balance at the end of the period	9.86	$ 9.87
Exercisable at end of the period	$ 10.05
Weighted Average Remaining Contractual Term (years)
Weighted average remaining contractual term, balance (years)	7 years 2 months 19 days
Exercisable at end of the period	6 years 11 months 15 days
Aggregate Intrinsic Value
Balance at the end of the period	$ 2,097,257
Exercisable at end of the period	$ 1,321,686
Stock Option Awards, Nonvested
Balance at the beginning of the period	1,196,545
Granted		583,565	289,890
Vested	(702,155)
Forfeited	(20,948)
Expired	(41,892)
Balance at the end of the period	431,550	1,196,545
Weighted Average Exercise Price, Nonvested
Balance at the beginning of the period	$ 2.66
Vested	2.73
Forfeited	2.82
Expired	2.82
Balance at the end of the period	$ 2.55	$ 2.66