SEGMENTS INFORMATION - Major Customers (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Revenue, Major Customer [Line Items]
Revenues	$ 324,651	$ 264,482
Operating Segments
Revenue, Major Customer [Line Items]
Revenues	324,703	264,814
Operating Segments | Europe
Revenue, Major Customer [Line Items]
Revenues	$ 132,707	$ 107,843
Sales Revenue, Net | Customer Concentration Risk | Operating Segments
Revenue, Major Customer [Line Items]
Number of customers	0
Sales Revenue, Net | Customer Concentration Risk | Operating Segments | Europe | UBS AG
Revenue, Major Customer [Line Items]
Number of customers		1
Revenues		$ 35,669
Accounts Receivable | Customer Concentration Risk | UBS AG | Billed Revenues
Revenue, Major Customer [Line Items]
Number of customers	1
Concentration percentage	11.90%
Accounts Receivable | Customer Concentration Risk | Expedia | Unbilled Revenues
Revenue, Major Customer [Line Items]
Number of customers	1
Concentration percentage	10.30%