COMMON STOCK PLANS - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted Average Price
Share-based compensation expense	$ 15,402	$ 19,641	$ 12,910
Restricted Stock and Restricted Stock Units | Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, vesting period	3 years
Shares
Nonvested, Beginning of Period (in shares)	325,643	184,942	99,574
Granted (in shares)	128,272	197,473	99,814
Forfeited (in shares)	(2,803)	(435)
Vested (in shares)	(45,576)	(56,337)	(14,446)
Nonvested, End of Period (in shares)	405,536	325,643	184,942
Weighted Average Price
Nonvested, Beginning of Period, Weighted Average Price (in dollars per share)	$ 44.44	$ 63.09	$ 59.60
Granted, Weighted Average Price (in dollars per share)	52.42	29.89	65.15
Forfeited, Weighted Average Price (in dollars per share)	44.68	40.73
Vested and paid, Weighted Average Price (in dollars per share)	65.68	54.70	53.20
Nonvested, End of Period, Weighted Average Price (in dollars per share)	$ 44.58	$ 44.44	$ 63.09
Share-based compensation expense	$ 6,700	$ 5,300	$ 6,000
Tax benefit related to stock-based compensation	1,300	$ 1,100	$ 1,000
Unrecognized compensation cost	$ 2,300
Remaining requisite service period (in years)	1 year 2 months 5 days