Property and Equipment - Schedule of Property and Equipment (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Property, Plant and Equipment [Line Items]    
Property and equipment, gross $ 98,657 $ 84,502
Less accumulated depreciation (64,917) (51,876)
Property and equipment, net 33,740 32,626
Computers and other related equipment [Member]
   
Property, Plant and Equipment [Line Items]    
Property and equipment, gross 40,016 33,680
Purchased and internally developed software [Member]
   
Property, Plant and Equipment [Line Items]    
Property and equipment, gross 52,616 45,074
Furniture and fixtures [Member]
   
Property, Plant and Equipment [Line Items]    
Property and equipment, gross 2,610 2,380
Leasehold improvements [Member]
   
Property, Plant and Equipment [Line Items]    
Property and equipment, gross $ 3,415 $ 3,368