SEGMENTS INFORMATION - Major Customers (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Revenue, Major Customer [Line Items]
Revenues	$ 348,977	$ 283,832	$ 673,628	$ 548,314
Operating Segments
Revenue, Major Customer [Line Items]
Revenues	349,021	283,977	673,724	548,791
Operating Segments | Europe
Revenue, Major Customer [Line Items]
Revenues	$ 141,319	$ 115,726	$ 274,026	$ 223,569
Sales Revenue, Net | Customer Concentration Risk | Operating Segments
Revenue, Major Customer [Line Items]
Number of customers	0		0
Sales Revenue, Net | Customer Concentration Risk | Operating Segments | Europe | UBS AG
Revenue, Major Customer [Line Items]
Number of customers		1		1
Revenues		$ 36,570		$ 72,239
Accounts Receivable | Customer Concentration Risk | Billed Revenues
Revenue, Major Customer [Line Items]
Number of customers			0
Accounts Receivable | Customer Concentration Risk | UBS AG | Unbilled Revenues
Revenue, Major Customer [Line Items]
Number of customers			1
Concentration percentage			16.00%