Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 48,094	$ 39,036
Investment receivable	20,000
Leasehold improvement receivable	13,474	13,474
Prepaid clinical and pre-clinical expenses	9,504	9,706
Payroll tax receivable	4,025	471
Prepaid maintenance services	3,343	2,994
Prepaid research expenses	2,519	1,932
Prepaid income tax	2,125	2,130
Prepaid commercial expenses	1,788	1,573
Other	5,927	6,466
Total other current assets	$ 110,799	$ 77,782