Business Combinations - Salveo Specialty Pharmacy Acquisition - Additional Information (Details) (USD $)
3 Months Ended 0 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Jan. 02, 2015
Business Acquisition [Line Items]      
Revenue $ 5,979,260,000 $ 4,914,479,000  
Amortization of intangible assets 52,619,000 54,986,000  
Future amortization expense, remainder of 2015 151,500,000    
Salveo Specialty Pharmacy, Inc [Member]      
Business Acquisition [Line Items]      
Stated purchase price     260,000,000
Revenue 157,800,000    
Goodwill expected to be tax deductible     199,000,000
Amortization of intangible assets 2,500,000    
Future amortization expense, remainder of 2015 $ 10,000,000