Fair Value Measurements - Activity of Level 3 Inputs Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning	$ 21,352	$ 23,127
Settlement of Ligand Contingent Consideration liability (Note 10(b))	(6,000)
Ending	14,445	21,352
Deferred Development Costs [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers in (out) of Level 3	(1,556)	(1,099)
Ligand Contingent Consideration [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers in (out) of Level 3	773	326
Talon CVR [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfers in (out) of Level 3	$ (124)	$ (1,002)