Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2011	Feb. 15, 2012	Jun. 30, 2011
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Trading Symbol	ARIA
Entity Registrant Name	ARIAD PHARMACEUTICALS INC
Entity Central Index Key	0000884731
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		158,929,544
Entity Public Float			$ 1,220,167,480