Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Mar. 06, 2017	Jun. 30, 2016
Document and Entity Information
Entity Registrant Name	Celldex Therapeutics, Inc.
Entity Central Index Key	0000744218
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 435
Entity Common Stock, Shares Outstanding		123,213,438
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY