Business Combinations - Catalyst Merger (Details) (USD $)
12 Months Ended 0 Months Ended 12 Months Ended 0 Months Ended 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Jul. 02, 2012
Catalyst
Dec. 31, 2013
Catalyst
Dec. 31, 2012
Catalyst
Jul. 02, 2012
Catalyst
Common Shares
Sep. 30, 2012
Catalyst
Initial Amounts Recognized at Acquisition Date
Dec. 31, 2013
Catalyst
Measurement Period Adjustments
Dec. 31, 2012
Catalyst
Measurement Period Adjustments
Dec. 31, 2013
Catalyst
Current Amounts Recognized at Acquisition Date
Dec. 31, 2012
Catalyst
Employees Settlements
Dec. 31, 2012
Catalyst
Severence Cost
Business Acquisition [Line Items]                          
Future amortization expense, 2014 $ 213,200,000                        
Merger Agreement [Abstract]                          
Stock conversion, share received per share converted             1.3212            
Stock conversion, cash received per share converted, prior to stock split             0.6606            
Stock conversion, cash received per share converted       $ 28                  
Shares issued             66,800,000            
Warrants, Issued             500,000            
Goodwill expected to be tax deductible       525,000,000                  
Amortization of intangible assets 203,192,000 130,116,000 16,385,000   166,100,000                
Fair value of intangible assets         1,200,000,000                
Customer relationships, weighted average useful life         9 years                
Business Combination, Consideration Transferred [Abstract]                          
Cash paid to shareholders       1,415,276,000                  
Fair value of common shares issued       3,238,141,000                  
Fair value of warrants and stock options issued       19,824,000                  
Total purchase price       4,673,241,000                  
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]                          
Cash and cash equivalents               93,775,000 0 (315,000) 93,460,000    
Other current assets               695,888,000 2,411,000 5,202,000 703,501,000    
Total current assets               789,663,000 2,411,000 4,887,000 796,961,000    
Goodwill 4,720,275,000 4,478,038,000 291,045,000         4,010,235,000 16,141,000 8,492,000 4,034,868,000    
Intangible assets               1,184,800,000 0 0 1,184,800,000    
Other long-term assets               87,174,000 8,000 1,547,000 88,729,000    
Total assets acquired               6,071,872,000 18,560,000 14,926,000 6,105,358,000    
Accounts payable               338,819,000 5,000 0 338,824,000    
Pharmacy benefit management rebates payable               176,202,000 (1,522,000) 2,935,000 177,615,000    
Accrued expenses and other current liabilities               187,851,000 5,473,000 1,348,000 194,672,000    
Long-term debt               311,994,000 0 0 311,994,000    
Other long-term liabilities               385,375,000 14,604,000 10,643,000 410,622,000    
Total liabilities assumed               1,400,241,000 18,560,000 14,926,000 1,433,727,000    
Non-controlling interest               (1,610,000) 0 0 (1,610,000)    
Net assets acquired               4,673,241,000 0 0 4,673,241,000    
Separate Tranactions and Preexisting Relationships [Abstract]                          
Integration and transaction related costs           27,200,000              
Transactions expenses           22,800,000              
Acquisition costs included in selling, general and administrative expenses           17,000,000              
Contract settlements and termination charges recorded           3,500,000              
Expenses and losses recognized                       3,100,000 10,400,000
Accounts receivable with acquired business           $ 4,100,000