Stockholders' Equity - Summary of Stock Option Activity (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Equity [Abstract]
Number of shares outstanding	18,912,000
Number of shares granted	885,000
Number of shares exercised	(369,978)
Number of shares expired and forfeited	(1,170,000)
Number of shares outstanding	18,257,000	18,912,000
Number of shares outstanding, weighted average exercise price	$ 19.59
Number of shares granted, weighted average exercise price	14.96
Number of shares exercised, weighted average exercise price	15.29
Number of shares expired and forfeited, weighted average exercise price	22.15
Number of shares outstanding, weighted average exercise price	$ 19.29	$ 19.59
Number of shares outstanding, weighted average remaining contractual term (Year)	6 years 6 months 10 days	7 years 2 months 15 days