Goodwill and Acquired Intangible Assets, Net (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Goodwill and Finite-lived Intangible Assets Rollforward [Roll Forward]    
Finite-Lived Intangible Assets, Net $ 144,270,000 $ 158,267,000
Finite-Lived Intangible Assets, Amortization Expense (6,192,000)  
Finite-lived intangible assets, other changes (7,805,000)  
Goodwill 560,747,000 599,863,000
Goodwill, Other Changes (39,116,000)  
Intangible Assets, Net (Including Goodwill) 705,017,000 758,130,000
Total intangible assets amortization expense (6,192,000)  
Total intangible assets, other changes (46,921,000)  
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year 14,300,000  
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 19,000,000  
Finite-Lived Intangible Assets, Amortization Expense, Year Two 17,100,000  
Finite-Lived Intangible Assets, Amortization Expense, Year Three 15,000,000  
Finite-Lived Intangible Assets, Amortization Expense, Year Four 14,300,000  
Finite-Lived Intangible Assets, Amortization Expense, Year Five $ 13,900,000