SEGMENT INFORMATION - Schedule of Total Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Items excluded from segment assets:
Deferred tax assets	$ 72,490	$ 75,065
Segment Assets	2,756,502	$ 2,707,099	$ 2,626,610
Corporate Reconciling Items and Eliminations
Items excluded from segment assets:
Cash and other investments	283,841		98
Deferred tax assets	72,490		192,563
Reportable Segments | Operating Segments
Items excluded from segment assets:
Segment Assets	1,903,324		1,938,811
All Other Segments | Operating Segments
Items excluded from segment assets:
Segment Assets	$ 496,847		$ 495,138