Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2011	Feb. 15, 2012	Jun. 30, 2011
Document Type	10-K
Amendment Flag	true
AmendmentDescription	The sole purpose of this Amendment No. 1 to the Annual Report on Form 10-K of ARIAD Pharmaceuticals, Inc. (the “Company”) for the fiscal year ended December 31, 2011, filed with the Securities and Exchange Commission on February 29, 2012 (the “Form 10-K”), is to furnish the Interactive Data Files on Exhibit 101. As permitted by Rule 405(a)(2)(ii) of Regulation S-T, the Company is furnishing the Interactive Data Files on Exhibit 101 by amendment within 30 days of the original filing date of the Form 10-K. No other changes have been made to the Form 10-K, and this Amendment has not been updated to reflect events occurring subsequent to the filing of the Form 10-K. Pursuant to Rule 406T of Regulation S-T, the Interactive Data Files on Exhibit 101 are deemed not filed or part of a registration statement or prospectus for purposes of Sections 11 or 12 of the Securities Act of 1933, as amended, are deemed not filed for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, and are otherwise not subject to liability under those sections.
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