Other Balance Sheet Items - Components of Accounts Payable, Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Clinical and preclinical	$ 45,635	$ 48,975
Accounts payable	23,791	22,696
Payroll and payroll-related	15,988	29,215
Royalties payable	21,015	20,665
Accrued professional services and other current liabilities	15,566	14,282
Taxes payable		32,565
Other payable to licensor		17,500
Interest payable		305
Total	$ 121,995	$ 186,203