Stockholders' Deficit - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ (103,141)
Issuance of shares pursuant to ARIAD stock plans			4,074
Stock-based compensation			9,377
Payments of tax withholding obligations related to stock compensation			(1,337)
Other comprehensive loss			(5,862)
Reclassification of currency translation adjustment and pension obligation adjustments to earnings upon sale of European operations	$ 2,939	$ 0	2,939	$ 0
Net Income	109,848	$ (63,160)	56,061	$ (115,835)
Ending Balance	$ (37,889)		$ (37,889)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)			189,662,148
Beginning Balance			$ 190
Issuance of shares pursuant to ARIAD stock plans (in shares)			2,459,257
Issuance of shares pursuant to ARIAD stock plans			$ 2
Ending Balance (in shares)	192,121,405		192,121,405
Ending Balance	$ 192		$ 192
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			1,338,585
Issuance of shares pursuant to ARIAD stock plans			4,072
Stock-based compensation			9,377
Payments of tax withholding obligations related to stock compensation			(1,337)
Ending Balance	1,350,697		1,350,697
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			3,835
Other comprehensive loss			(5,862)
Reclassification of currency translation adjustment and pension obligation adjustments to earnings upon sale of European operations			2,939
Ending Balance	912		912
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(1,445,751)
Net Income			56,061
Ending Balance	$ (1,389,690)		$ (1,389,690)