Document and Entity Information
3 Months Ended
Mar. 31, 2012
Apr. 26, 2012
Document and Entity Information    
Entity Registrant Name Celldex Therapeutics, Inc.  
Entity Central Index Key 0000744218  
Document Type 10-Q  
Document Period End Date Mar. 31, 2012  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   58,735,636
Document Fiscal Year Focus 2012  
Document Fiscal Period Focus Q1