PROPERTY AND EQUIPMENT (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment
Property and equipment, gross	$ 312,787	$ 232,483
Less: accumulated depreciation and amortization	(177,734)	(143,214)
Property and equipment, net	135,053	89,269
Depreciation	48,365	32,818	20,648
Computer equipment and software
Property, Plant and Equipment
Property and equipment, gross	244,845	193,282
Office equipment, furniture and fixtures and leasehold improvements
Property, Plant and Equipment
Property and equipment, gross	$ 67,942	$ 39,201
Minimum [Member] | Computer equipment and software
Property, Plant and Equipment
Estimated Useful Lives (years)	2 years
Minimum [Member] | Office equipment, furniture and fixtures and leasehold improvements
Property, Plant and Equipment
Estimated Useful Lives (years)	2 years
Maximum [Member] | Computer equipment and software
Property, Plant and Equipment
Estimated Useful Lives (years)	5 years
Maximum [Member] | Office equipment, furniture and fixtures and leasehold improvements
Property, Plant and Equipment
Estimated Useful Lives (years)	11 years