STOCK-BASED COMPENSATION (Fair Value of Restricted Stock and Restricted Stock Units Vested) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Service Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	$ 27,038	$ 14,363	$ 20,397
Performance Targets
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	9,085	8,993	8,152
Equity Classified Award | Service Period | Equity-Settled Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	12,607	11,431	19,305
Equity Classified Award | Service Period | Equity-Settled Award | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	10,620	2,932	1,092
Equity Classified Award | Performance Targets | Equity-Settled Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	452	690	789
Equity Classified Award | Performance Targets | Equity-Settled Award | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	0	348	0
Liability Classified Award | Service Period | Cash-Settled Award | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	3,811	0	0
Liability Classified Award | Performance Targets | Equity-Settled Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	$ 8,633	$ 7,955	$ 7,363