Other Balance Sheet Items - Components of Accounts Payable, Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Clinical and preclinical	$ 44,749	$ 48,975
Accrued professional services and other current liabilities	24,893	14,282
Payroll and payroll-related	22,980	29,215
Royalties payable	22,740	20,665
Accounts payable	19,664	22,696
Taxes payable		32,565
Other payable to licensor		17,500
Interest payable		305
Total	$ 135,026	$ 186,203