v2.4.0.8
Document and Entity Information
3 Months Ended
Mar. 31, 2014
Apr. 17, 2014
Common Stock
Apr. 17, 2014
Class A Stock
Entity Information [Line Items]      
Entity Registrant Name REGENERON PHARMACEUTICALS INC    
Entity Central Index Key 0000872589    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Document Type 10-Q    
Document Period End Date Mar. 31, 2014    
Document Fiscal Year Focus 2014    
Document Fiscal Period Focus Q1    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   98,879,794 2,000,781