Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock-Based Compensation
Stock-based compensation expense	$ 3,400		$ 3,100		$ 5,800	$ 4,800
Proceeds from exercise of stock options					$ 3,075	$ 7,282
Common Stock
Stock-Based Compensation
Exercise of stock options (in shares)	72,000	268,000	343,000	540,000
Common Stock | 2020 Employee stock purchase plan
Stock-Based Compensation
Exercise of stock options (in shares)	300,000		600,000		700,000	1,200,000
Proceeds from exercise of stock options	$ 1,100		$ 3,300		$ 3,600	$ 7,800
2000 Stock Plan
Stock-Based Compensation
Awards granted (in shares)					0
2000 Stock Plan | Stock Options
Stock-Based Compensation
Options Expiration period					10 years