Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 114,659	$ 134,430
Prepaid clinical and pre-clinical expenses	17,539	16,224
Collaboration receivable	15,105	34,184
Prepaid maintenance services	8,063	6,411
Prepaid research expenses	4,620	5,854
Prepaid income tax	3,930	4,939
Leasehold improvement receivable	3,059	3,059
Prepaid insurance	2,637	4,158
Other	5,369	4,065
Total other current assets	$ 174,981	$ 213,324