SEGMENT INFORMATION - Schedule of Total Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Items excluded from segment assets:
Deferred tax assets	$ 72,120	$ 75,065
Segment Assets	2,745,928	$ 2,707,099	$ 2,588,529
Corporate Reconciling Items and Eliminations
Items excluded from segment assets:
Cash and other investments	275,377		86,131
Deferred tax assets	72,120		189,380
Reportable Segments | Operating Segments
Items excluded from segment assets:
Segment Assets	1,891,606		1,912,656
All Other Segments | Operating Segments
Items excluded from segment assets:
Segment Assets	$ 506,825		$ 400,362