Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued expenses:
Product revenue allowances	$ 15,540	$ 12,858
Selling, general and administrative expenses	5,349	5,544
Research and development expenses	4,363	3,379
Payroll expenses	6,686	7,810
Inventory purchases	2,581	1,230
Other	858	558
Total accrued expenses	35,377	31,379
Other current liabilities:
Lease liability	1,904	1,135
Total other current liabilities	1,904	1,135
Total accrued expenses and other current liabilities	$ 37,281	$ 32,514