SHAREHOLDERS' EQUITY - Options Outstanding and Exercisable (Details) - Employee Stock Option - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares
Outstanding at beginning of year (in shares)	1,001,300	1,410,250	954,625
Granted (in shares)	17,550	10,000	670,000
Exercised (in shares)	(400,203)	(138,450)	0
Cancelled or expired (in shares)	(22,499)	(280,500)	(214,375)
Outstanding at end of year (in shares)	596,148	1,001,300	1,410,250
Options exercisable at year end (in shares)	341,515	588,802	750,250
Weighted average fair value per option granted during the year (in dollars per share)	$ 12.87	$ 10.69	$ 3.94
Weighted Avg. Exercise Price
Outstanding at beginning of year (in dollars per share)	11.58	12.57	15.98
Granted (in dollars per share)	31.66	24.36	8.43
Exercised (in dollars per share)	12.18	13.49	0.00
Cancelled or expired (in dollars per share)	15.24	16.04	14.86
Outstanding at end of year (in dollars per share)	$ 11.64	$ 11.58	$ 12.57