Stock-Based Compensation - Schedule of option activity (Details) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, Options outstanding (in shares)				2,320,318	2,543,125		2,473,198
Options granted (in shares)				223,638	528,077		0
Options exercised (in shares)				(500)	(52,799)		(6,821)
Options cancelled (in shares)				(331)	(139,395)		(146,059)
Ending balance, Options outstanding (in shares)	2,543,125	2,320,318	2,473,198	2,543,125	2,879,008	2,543,125	2,320,318
Exercisable at period end (in shares)	2,283,243	2,267,154		2,283,243	2,206,259	2,283,243	2,267,154
Weighted Average Exercise Price per Share
Beginning of period (in dollars per share)				$ 4.67	$ 4.82		$ 4.67
Options granted (in dollars per share)				6.37	6.31		0
Options exercised (in dollars per share)				3.14	4.19		3.78
Options cancelled (in dollars per share)				9.29	9.52		5.88
End of period (in dollars per share)	$ 4.82	$ 4.67	$ 4.67	4.82	4.88	$ 4.82	4.67
Exercisable at end of period (in usd per share)	$ 4.70	$ 4.70		$ 4.70	$ 4.44	$ 4.70	$ 4.70
Weighted Average Remaining Contractual Term (in Years)
Options outstanding, weighted average remaining contractual term (in years)	6 years 18 days	5 years 11 months 1 day	6 years 10 months 2 days		6 years 7 days	6 years 18 days
Options exercisable, weighted average remaining contractual term (in years)	5 years 7 months 24 days	5 years 10 months 9 days			4 years 11 months 26 days
Aggregate Intrinsic Value (in thousands)
Options outstanding, aggregate intrinsic value	$ 0	$ 0	$ 0	$ 0	$ 6,747	$ 0	$ 0
Options exercisable, aggregate intrinsic value	$ 0	$ 0		$ 0	$ 5,984	$ 0	$ 0
Closing stock price (in dollars per share)	$ 3.75	$ 3.01		$ 3.75	$ 7.07	$ 3.75	$ 3.01