Property and Equipment (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property, Plant and Equipment [Line Items]      
Cost $ 354,247,000 $ 300,865,000  
Accumulated Depreciation (144,220,000) (103,858,000)  
Net Book Value 210,027,000 197,007,000  
Depreciation 63,468,000 42,232,000 20,234,000
Depreciation, cost of revenue 4,000,000 4,300,000 3,500,000
Furniture and equipment      
Property, Plant and Equipment [Line Items]      
Cost 39,690,000 30,374,000  
Accumulated Depreciation (13,577,000) (10,815,000)  
Net Book Value 26,113,000 19,559,000  
Computer equipment and software      
Property, Plant and Equipment [Line Items]      
Cost 208,628,000 168,463,000  
Accumulated Depreciation (107,565,000) (77,880,000)  
Net Book Value 101,063,000 90,583,000  
Leasehold improvements      
Property, Plant and Equipment [Line Items]      
Cost 96,784,000 91,294,000  
Accumulated Depreciation (23,078,000) (15,163,000)  
Net Book Value 73,706,000 76,131,000  
Construction in progress      
Property, Plant and Equipment [Line Items]      
Cost 9,145,000 10,734,000  
Accumulated Depreciation 0 0  
Net Book Value $ 9,145,000 $ 10,734,000