Stockholders' Deficit - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stockholders Equity Note [Line Items]
Beginning Balance	$ (103,141)
Issuance of shares pursuant to ARIAD stock plans	777
Stock-based compensation	6,719
Payments of tax withholding obligations related to stock compensation	(617)
Other comprehensive loss	(3,963)	$ 313
Net Loss	(53,787)	$ (52,676)
Ending Balance	$ (154,012)
Common Stock
Stockholders Equity Note [Line Items]
Beginning Balance (in shares)	189,662,148
Beginning Balance	$ 190
Issuance of shares pursuant to ARIAD stock plans (in shares)	1,397,992
Issuance of shares pursuant to ARIAD stock plans	$ 1
Ending Balance (in shares)	191,060,140
Ending Balance	$ 191
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Beginning Balance	1,338,585
Issuance of shares pursuant to ARIAD stock plans	776
Stock-based compensation	6,719
Payments of tax withholding obligations related to stock compensation	(617)
Ending Balance	1,345,463
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Beginning Balance	3,835
Other comprehensive loss	(3,963)
Ending Balance	(128)
Accumulated Deficit
Stockholders Equity Note [Line Items]
Beginning Balance	(1,445,751)
Net Loss	(53,787)
Ending Balance	$ (1,499,538)