CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2008	$ (69,198)	$ 71	$ 369,313	$ 18	$ (438,600)
Beginning Balance (in shares) at Dec. 31, 2008		71,365,339
Issuance of shares pursuant to ARIAD stock plans (in shares)		995,893
Issuance of shares pursuant to ARIAD stock plans	568	1	567
Issuance of shares to minority shareholders of AGTI (in shares)		452,852
Issuance of shares to minority shareholders of AGTI	474	1	473
Issuance of common stock, net of issuance costs (in shares)		36,228,698
Issuance of common stock, net of issuance costs	58,370	36	58,334
Issuance of warrants	(3,559)		(3,559)
Stock-based compensation	4,355		4,355
Comprehensive (loss) income:
Net (loss) income	(80,008)				(80,008)
Net unrealized losses on marketable securities	(18)			(18)
Total comprehensive (loss) income	(80,026)
Ending Balance at Dec. 31, 2009	(89,016)	109	429,483		(518,608)
Ending Balance (in shares) at Dec. 31, 2009		109,042,782
Issuance of shares pursuant to ARIAD stock plans (in shares)		679,235
Issuance of shares pursuant to ARIAD stock plans	789	1	788
Issuance of common stock, net of issuance costs (in shares)		16,000,000
Issuance of common stock, net of issuance costs	57,515	16	57,499
Issuance of common stock from warrant exercise (in shares)	1,220,414	1,220,414
Issuance of common stock from warrant exercise	4,704	1	4,703
Stock-based compensation	4,836		4,836
Comprehensive (loss) income:
Net (loss) income	85,248				85,248
Total comprehensive (loss) income	85,248
Ending Balance at Dec. 31, 2010	64,076	127	497,309		(433,360)
Ending Balance (in shares) at Dec. 31, 2010		126,942,431
Issuance of shares pursuant to ARIAD stock plans (in shares)		2,183,504
Issuance of shares pursuant to ARIAD stock plans	4,791	2	4,789
Issuance of common stock, net of issuance costs (in shares)		24,725,000
Issuance of common stock, net of issuance costs	243,058	25	243,033
Issuance of common stock from warrant exercise (in shares)	3,757,767	3,757,767
Issuance of common stock from warrant exercise	24,971	4	24,967
Stock-based compensation	7,675		7,675
Payments of tax withholding obligations related to stock compensation	(827)		(827)
Comprehensive (loss) income:
Net (loss) income	(123,603)				(123,603)
Total comprehensive (loss) income	(123,603)
Ending Balance at Dec. 31, 2011	$ 220,141	$ 158	$ 776,946		$ (556,963)
Ending Balance (in shares) at Dec. 31, 2011		157,608,702