XML 23 R1.htm IDEA: XBRL DOCUMENT v3.10.0.1
Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2018
Feb. 22, 2019
Jun. 29, 2018
Document Information [Line Items]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2018    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Entity Registrant Name REPLIGEN CORP    
Trading Symbol RGEN    
Entity Central Index Key 0000730272    
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 Large Accelerated Filer    
Entity Shell Company false    
Emerging growth company false    
Smaller reporting company false    
Entity Common Stock, Shares Outstanding   43,921,488  
Entity Public Float     $ 1,569,493,598