SEGMENT INFORMATION - Geographic Information about Revenue and Long-Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenue and long-lived assets by geography
Revenue	$ 1,104,592	$ 828,434	$ 3,158,789	$ 2,356,654
Property and equipment, net of accumulated depreciation and amortization	308,465		308,465		$ 315,170
United States
Revenue and long-lived assets by geography
Revenue	738,599	577,362	2,104,750	1,670,980
Property and equipment, net of accumulated depreciation and amortization	279,690		279,690		286,541
All other countries
Revenue and long-lived assets by geography
Revenue	365,993	$ 251,072	1,054,039	$ 685,674
Property and equipment, net of accumulated depreciation and amortization	$ 28,775		$ 28,775		$ 28,629