SHARE-BASED COMPENSATION - Deferred Compensation Costs (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation costs related to unvested awards	$ 30,356	$ 14,669
Service based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation costs related to unvested awards	17,845	8,918
Performance based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation costs related to unvested awards	9,475	4,752
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation costs related to unvested awards	27,320	13,670
SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation costs related to unvested awards	3,036	999
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation costs related to unvested awards	$ 0	$ 0