Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 39,036	$ 18,650
Leasehold improvement receivable	13,474
Prepaid clinical and pre-clinical expenses	9,706	5,175
Prepaid maintenance services	2,994	1,711
Prepaid income tax	2,130
Prepaid research expenses	1,932	2,896
Interest receivable	1,918	709
Prepaid commercial expenses	1,573	1,589
Asset held for sale		1,501
Other prepaids	3,671	2,726
Other	1,348	1,554
Total other current assets	$ 77,782	$ 36,511