Stockholders' Deficit - Schedule of Changes in Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ (103,141)
Issuance of shares pursuant to ARIAD stock plans			14,234
Stock-based compensation			14,659
Payments of tax withholding obligations related to stock compensation			(1,541)
Other comprehensive loss			(1,733)
Reclassification of currency translation adjustment and pension obligation adjustments to earnings upon sale of European operations	$ 0	$ 0	2,939	$ 0
Net Income	(27,827)	$ (55,451)	28,234	$ (171,285)
Ending Balance	$ (46,349)		$ (46,349)
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)			4,429,744
Issuance of shares pursuant to ARIAD stock plans			$ 4
Ending Balance (in shares)	194,091,892		194,091,892
Ending Balance	$ 194		$ 194
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			1,338,585
Issuance of shares pursuant to ARIAD stock plans			14,230
Stock-based compensation			14,659
Payments of tax withholding obligations related to stock compensation			(1,541)
Ending Balance	1,365,933		1,365,933
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	912		3,835
Other comprehensive loss			(1,733)
Reclassification of currency translation adjustment and pension obligation adjustments to earnings upon sale of European operations			2,939
Ending Balance	5,041		5,041
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(1,445,751)
Net Income			28,234
Ending Balance	$ (1,417,517)		$ (1,417,517)