XML 11 R1.htm IDEA: XBRL DOCUMENT v3.19.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2019
May 03, 2019
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Mar. 31, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1  
Entity Registrant Name REPLIGEN CORP  
Entity Central Index Key 0000730272  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Trading Symbol RGEN  
Entity Common Stock, Shares Outstanding   47,225,369
Emerging growth company false  
Smaller reporting company false