Summary of Significant Accounting Policies - Product Revenue Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Movement In Product Revenue Allowance And Reserve [Roll Forward]
Balance at January 1	$ 534
Provision related to current period sales	182	$ 635
Adjustment related to prior period sales	194
Credit or payments made during the period	(248)	(101)
Balance at December 31	$ 662	$ 534