Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 18,465	$ 18,650
Leasehold improvement receivable	10,787
Prepaid clinical and pre-clinical expenses	10,658	5,175
Prepaid maintenance and license fees	2,415	1,711
Prepaid research expenses	1,939	2,896
Prepaid commercial expenses	2,125	1,589
Asset held for sale		1,501
Other prepaids	3,537	2,726
Other	4,874	2,263
Total other current assets	$ 54,800	$ 36,511