Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 134,430	$ 54,276
Collaboration receivable	34,184
Prepaid clinical and pre-clinical expenses	16,224	8,263
Prepaid maintenance services	6,411	4,366
Prepaid research expenses	5,854	2,007
Prepaid income tax	4,939	2,114
Prepaid insurance	4,158	2,573
Leasehold improvement receivable	3,059	3,059
Other	4,065	5,249
Total other current assets	$ 213,324	$ 81,907