CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2012		167,075,758
Beginning Balance at Dec. 31, 2012	$ 112,851	$ 167	$ 890,499	$ 20	$ (777,835)
Issuance of shares pursuant to ARIAD stock plans (in shares)		2,330,429
Issuance of shares pursuant to ARIAD stock plans	6,284	$ 2	6,282
Issuance of common stock, net of issuance costs (in shares)		16,489,893
Issuance of common stock, net of issuance costs	310,037	$ 17	310,020
Stock-based compensation	35,421		35,421
Payments of tax withholding obligations related to stock compensation	(3,363)		(3,363)
Net loss	(274,158)				(274,158)
Other comprehensive income (loss)	(1,555)			(1,555)
Ending Balance (in shares) at Dec. 31, 2013		185,896,080
Ending Balance at Dec. 31, 2013	185,517	$ 186	1,238,859	(1,535)	(1,051,993)
Issuance of shares pursuant to ARIAD stock plans (in shares)		1,398,014
Issuance of shares pursuant to ARIAD stock plans	3,694	$ 1	3,693
Equity component of convertible debt issuance	25,255		25,255
Stock-based compensation	32,403		32,403
Payments of tax withholding obligations related to stock compensation	(816)		(816)
Net loss	(162,602)				(162,602)
Other comprehensive income (loss)	(2,650)			(2,650)
Ending Balance (in shares) at Dec. 31, 2014		187,294,094
Ending Balance at Dec. 31, 2014	80,801	$ 187	1,299,394	(4,185)	(1,214,595)
Issuance of shares pursuant to ARIAD stock plans (in shares)		2,368,054
Issuance of shares pursuant to ARIAD stock plans	4,436	$ 3	4,433
Stock-based compensation	37,020		37,020
Payments of tax withholding obligations related to stock compensation	(2,262)		(2,262)
Net loss	(231,156)				(231,156)
Other comprehensive income (loss)	8,020			8,020
Ending Balance (in shares) at Dec. 31, 2015		189,662,148
Ending Balance at Dec. 31, 2015	$ (103,141)	$ 190	$ 1,338,585	$ 3,835	$ (1,445,751)