v2.4.0.8
Document and Entity Information
6 Months Ended
Jun. 30, 2015
Jul. 17, 2015
Common Stock
Jul. 17, 2015
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 Jun. 30, 2015    
Document Fiscal Year Focus 2015    
Document Fiscal Period Focus Q2    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   101,736,534 1,951,868