Prepaid Expenses - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid expenses	$ 8,863	$ 4,805
Prepaid R&D clinical costs	8,498	4,377
Prepaid insurance	181	245
Other prepaid costs	$ 184	$ 183