Goodwill and Intangible Assets (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Goodwill [Line Items]      
Goodwill $ 66,548 $ 47,000 $ 15,830
Goodwill Acquired During Period 19,548 31,170  
Finite-Lived Intangible Assets, Net [Abstract]      
Finite-Lived Intangible Assets, Gross 74,774 48,910  
Less: Accumulated amortization (17,250) (10,767)  
Intangible Assets, Net 57,524 38,143  
Amortization expense related to intangible assets 6,500 3,400 3,100
Amortization Expense, Maturity Schedule [Abstract]      
2014 7,921    
2015 7,556    
2016 6,814    
2017 5,248    
2018 4,879    
Minimum [Member]
     
Finite-Lived Intangible Assets, Net [Abstract]      
Useful life of acquired intangible assets 3 years    
Maximum [Member]
     
Finite-Lived Intangible Assets, Net [Abstract]      
Useful life of acquired intangible assets 12 years    
Acquired Technology [Member]
     
Finite-Lived Intangible Assets [Line Items]      
Weighted Average Amortization Period 7 years    
Finite-Lived Intangible Assets, Net [Abstract]      
Finite-Lived Intangible Assets, Gross 14,904 12,483  
Acquired Technology [Member] | Minimum [Member]
     
Finite-Lived Intangible Assets [Line Items]      
Weighted Average Amortization Period 3 years    
Acquired Technology [Member] | Maximum [Member]
     
Finite-Lived Intangible Assets [Line Items]      
Weighted Average Amortization Period 7 years    
Internal Use Software [Member]
     
Finite-Lived Intangible Assets [Line Items]      
Weighted Average Amortization Period 3 years    
Finite-Lived Intangible Assets, Net [Abstract]      
Finite-Lived Intangible Assets, Gross 2,212 422  
Contracts and Customer Lists [Member]
     
Finite-Lived Intangible Assets [Line Items]      
Weighted Average Amortization Period 11 years    
Finite-Lived Intangible Assets, Net [Abstract]      
Finite-Lived Intangible Assets, Gross 46,681 25,441  
Trademarks and Domain Names [Member]
     
Finite-Lived Intangible Assets [Line Items]      
Weighted Average Amortization Period 9 years    
Finite-Lived Intangible Assets, Net [Abstract]      
Finite-Lived Intangible Assets, Gross 1,150 1,150  
Covenants Not to Compete [Member]
     
Finite-Lived Intangible Assets [Line Items]      
Weighted Average Amortization Period 5 years    
Finite-Lived Intangible Assets, Net [Abstract]      
Finite-Lived Intangible Assets, Gross 5,016 5,016  
Internal Use Software in Development [Member]
     
Finite-Lived Intangible Assets, Net [Abstract]      
Finite-Lived Intangible Assets, Gross $ 4,811 $ 4,398