SEGMENTS INFORMATION - Major Customers (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)
Revenue, Major Customer [Line Items]
Revenues	$ 283,832	$ 217,781	$ 548,314	$ 417,826
Operating Segments
Revenue, Major Customer [Line Items]
Revenues	283,977	218,069	548,791	418,263
Operating Segments | Europe
Revenue, Major Customer [Line Items]
Revenues	$ 115,726	$ 98,160	$ 223,569	$ 189,312
Sales Revenue, Net | Customer Concentration Risk | Operating Segments | Europe | UBS AG
Revenue, Major Customer [Line Items]
Number of customers	1	1	1	1
Revenues	$ 36,570	$ 31,933	$ 72,239	$ 62,867
Accounts Receivable | Customer Concentration Risk | Unbilled Revenues
Revenue, Major Customer [Line Items]
Number of customers			0
Accounts Receivable | Customer Concentration Risk | UBS AG | Billed Revenues
Revenue, Major Customer [Line Items]
Number of customers			1
Concentration percentage			14.20%
Accounts Receivable | Customer Concentration Risk | UBS AG | Unbilled Revenues
Revenue, Major Customer [Line Items]
Concentration percentage			0.00%