STOCK-BASED PLANS (Summary of Restricted Stock Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Average Grant Date Fair Value
Stock based compensation expense	$ 12,128	$ 7,385	$ 6,707
Restricted Stock
Stock-based plans
Vesting period	5 years
Restricted stock activity
Restricted stock outstanding at the beginning of the period (in shares)	354,519	289,112	242,556
Granted (in shares)	142,332	177,708	136,198
Vested (in shares)	(52,479)	(68,819)	(37,670)
Forfeited (in shares)	(37,828)	(43,482)	(51,972)
Restricted stock outstanding at the end of the period (in shares)	406,544	354,519	289,112
Weighted Average Grant Date Fair Value
Restricted stock outstanding at the beginning of the period (in dollars per share)	$ 89.00	$ 88.88	$ 100.15
Granted (in dollars per share)	83.09	85.88	67.80
Vested (in dollars per share)	124.50	88.58	83.47
Forfeited (in dollars per share)	91.71	76.10	90.14
Restricted stock outstanding at the end of the period (in dollars per share)	$ 82.10	$ 89.00	$ 88.88
Fair value of restricted stock vested	$ 5,500
Unamortized restricted stock expense	$ 21,600
Weighted-average period for recognition of unamortized restricted stock expense	3 years 9 months 18 days
Restricted Stock | General and Administrative Expense
Weighted Average Grant Date Fair Value
Stock based compensation expense	$ 7,500	$ 5,700	$ 4,500