Liabilities Measured at Fair Value Using Level 3 Inputs (Detail) - Contingent Payment $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent acquisition consideration payable, Beginning balance	$ 42,662
Addition of contingent consideration payable related to the Prosensa acquisition	71,402
Reversal of contingent liability related to no early FDA approval for Kyndrisa	(39,726)
Changes in the fair value of other acquisition contingent consideration payable	11,271
Contingent acquisition consideration payable, Ending balance	$ 85,609