OPERATING SEGMENTS (Major Customers) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Revenue, Major Customer [Line Items]
Revenues	$ 260,253	$ 236,049	$ 217,781	$ 200,045	$ 202,184	$ 192,764	$ 174,695	$ 160,384	$ 914,128	$ 730,027	$ 555,117
Operating Segments
Revenue, Major Customer [Line Items]
Revenues									914,966	730,003	555,043
Operating Segments | Europe
Revenue, Major Customer [Line Items]
Revenues									$ 400,460	$ 299,279	$ 204,150
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	1
Revenues									$ 130,605	$ 97,872
Accounts Receivable | Customer Concentration Risk | Operating Segments | Europe | UBS AG | Billed Revenues [Member]
Revenue, Major Customer [Line Items]
Number of customers									1
Concentration percentage									12.40%
Accounts Receivable | Customer Concentration Risk | Operating Segments | Europe | UBS AG | Unbilled Revenues [Member]
Revenue, Major Customer [Line Items]
Number of customers									1
Concentration percentage									19.80%