v2.4.0.8
Document and Entity Information (USD $)
12 Months Ended
Dec. 31, 2014
Mar. 01, 2015
Jun. 30, 2014
Document Information [Line Items]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2014    
Document Fiscal Year Focus 2014    
Document Fiscal Period Focus FY    
Trading Symbol ACHN    
Entity Registrant Name ACHILLION PHARMACEUTICALS INC    
Entity Central Index Key 0001070336    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Accelerated Filer    
Entity Common Stock, Shares Outstanding   117,539,994  
Entity Public Float     $ 522,706,085