STOCK-BASED COMPENSATION - Stock-Based Comp Expense (Details) - Time Lapse Restricted Shares - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	$ 12,399	$ 12,415	$ 12,110
Tax benefit	(4,799)	(4,805)	(4,687)
Restricted stock expense, net of tax	$ 7,600	$ 7,610	$ 7,423