SHAREHOLDERS' EQUITY - Options Outstanding and Exercisable (Details) - Employee Stock Option - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Outstanding at beginning of year (in shares)	596,148	1,001,300	1,410,250
Granted (in shares)	1,038,536	17,550	10,000
Exercised (in shares)	(224,750)	(400,203)	(138,450)
Cancelled or expired (in shares)	(645,150)	(22,499)	(280,500)
Outstanding at end of year (in shares)	764,784	596,148	1,001,300
Options exercisable at year end (in shares)	227,598	341,515	588,802
Weighted average fair value per option granted during the year (in dollars per share)	$ 9.16	$ 12.87	$ 10.69
Weighted Avg. Exercise Price
Outstanding at beginning of year (in dollars per share)	11.64	11.58	12.57
Granted (in dollars per share)	15.76	31.66	24.36
Exercised (in dollars per share)	8.92	12.18	13.49
Cancelled or expired (in dollars per share)	12.50	15.24	16.04
Outstanding at end of year (in dollars per share)	$ 17.31	$ 11.64	$ 11.58