SHAREHOLDERS' EQUITY - Options Outstanding and Exercisable (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares
Outstanding at beginning of year (in shares)	1,410,250	954,625	1,127,250
Granted (in shares)	10,000	670,000	25,000
Exercised (in shares)	(138,450)	0	(4,000)
Cancelled or expired (in shares)	(280,500)	(214,375)	(193,625)
Outstanding at end of year (in shares)	1,001,300	1,410,250	954,625
Options exercisable at year end (in shares)	588,802	750,250	832,125
Weighted average fair value per option granted during the year (in dollars per share)	$ 10.69	$ 3.94	$ 4.44
Weighted Avg. Exercise Price
Outstanding at beginning of year (in dollars per share)	12.57	15.98	16.12
Granted (in dollars per share)	24.36	8.43	10.62
Exercised (in dollars per share)	13.49	0.00	6.30
Cancelled or expired (in dollars per share)	16.04	14.86	16.29
Outstanding at end of year (in dollars per share)	$ 11.58	$ 12.57	$ 15.98
Total intrinsic value of options exercised	$ 1.3	$ 0.0	$ 0.0