Prepaid Expenses - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid expenses	$ 10,124	$ 8,863
Prepaid R&D clinical costs	8,499	8,498
Prepaid insurance	1,170	181
Other prepaid costs	$ 455	$ 184