Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued expenses and other current liabilities:
Accrued compensation and benefits	$ 11,609	$ 11,169
Accrued consulting and professional fees	3,345	3,810
Accrued research and development expenses	4,379	8,734
Accrued revenue reserves	54,546	38,450
Accrued other	4,927	3,213
Total accrued expenses and other current liabilities	$ 78,806	$ 65,376