STOCK-BASED PLANS (Summary of Restricted Stock Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Weighted Average Grant Date Fair Value
Stock based compensation expense	$ 19,502	$ 12,128	$ 7,385
Restricted Stock
Restricted stock activity
Restricted stock outstanding at the beginning of the period (in shares)	406,544	354,519	289,112
Granted (in shares)	236,145	142,332	177,708
Vested (in shares)	(118,560)	(52,479)	(68,819)
Forfeited (in shares)	(117,327)	(37,828)	(43,482)
Restricted stock outstanding at the end of the period (in shares)	406,802	406,544	354,519
Weighted Average Grant Date Fair Value
Restricted stock outstanding at the beginning of the period (in dollars per share)	$ 82.10	$ 89.00	$ 88.88
Granted (in dollars per share)	98.78	83.09	85.88
Vested (in dollars per share)	122.51	124.50	88.58
Forfeited (in dollars per share)	95.03	91.71	76.10
Restricted stock outstanding at the end of the period (in dollars per share)	$ 76.27	$ 82.10	$ 89.00
Fair value of restricted stock vested	$ 14,900
Unamortized restricted stock expense	$ 18,400
Weighted-average period for recognition of unamortized restricted stock expense	3 years
Restricted Stock | General and Administrative Expense
Weighted Average Grant Date Fair Value
Stock based compensation expense	$ 16,700	$ 7,500	$ 5,700
Minimum | Restricted Stock
Stock-based plans
Vesting period	3 years
Maximum | Restricted Stock
Stock-based plans
Vesting period	5 years