SEGMENT REPORTING - Total Revenues Based on Location of the Customer and Long-Lived Assets by Geographic Regions (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total revenues
Total Revenues	$ 3,959,786	$ 3,784,451	$ 3,710,018	$ 3,415,125	$ 3,414,975	$ 3,355,754	$ 3,299,741	$ 3,073,943	$ 14,869,380	$ 13,144,413	$ 13,476,084
Long-lived assets
Total long-lived assets	442,212				444,610				442,212	444,610	345,323
United States
Total revenues
Total Revenues									12,865,087	11,749,602	12,097,633
Long-lived assets
Total long-lived assets	335,072				348,299				335,072	348,299	320,445
Other locations
Total revenues
Total Revenues									2,004,293	1,394,811	1,378,451
Long-lived assets
Total long-lived assets	$ 107,140				$ 96,311				$ 107,140	$ 96,311	$ 24,878