STOCK OPTIONS - Stock option activity (Details) - 2008 Stock Option Plan - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Shares
Outstanding at beginning of period	173,050	199,450	639,300
Exercised	(11,200)	(25,400)	(431,550)
Forfeited	(14,700)	(1,000)	(8,300)
Outstanding at end of period	147,150	173,050	199,450
Exercisable at end of period	147,150	173,050	199,450
Weighted Average Exercise Price (in $ per share)
Outstanding at beginning of period (in dollars per share)	$ 2.06	$ 2.05	$ 2.12
Exercised	1.23	1.91	2.14
Forfeited	2.75	2.75	2.75
Outstanding at end of period (in dollars per share)	2.06	2.06	2.05
Exercisable at end of period	$ 2.06	$ 2.06	$ 2.05