Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued clinical and preclinical costs	$ 12,283	$ 9,587
Accrued up-front license payment to UWA (Note 3)	7,000
Accrued employee compensation costs	5,567	8,189
Accrued contract manufacturing costs	3,755	4,830
Accrued professional fees	2,600	4,258
Accrued research costs	1,310	629
Other	2,549	1,560
Total accrued expenses	$ 35,064	$ 29,053