Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2022	Dec. 31, 2020	Dec. 31, 2019
Stock Option Activity and Outstanding Options
Options outstanding (in shares)	740	710
Forfeited, canceled or expired (in shares)	(22)	(1)
Exercised (in shares)	(9)	(238)
Options outstanding (in shares)	710	471	740
Stock Option Activity and Weighted-Average Exercise Price
Beginning of period, Weighted Average Exercise Price (in dollars per share)	$ 2.20	$ 1.89
Forfeited, canceled or expired, Weighted Average Exercise Price (in dollars per share)	8.22	2.72
Exercises, Weighted Average Exercise Price (in dollars per share)	11.5	2.01
End of period, Weighted Average Exercise Price (in dollars per share)	$ 1.89	$ 1.82	$ 2.20
Options outstanding, Number (in shares)	710	471	740
Options outstanding, Weighted Average Exercise Price (in dollars per share)	$ 1.89	$ 1.82	$ 2.20
Options outstanding, Aggregate Intrinsic Value		$ 1,101
Options outstanding, Weighted-Average Remaining Contractual Life		5 years 4 months 24 days
Options exercisable, Number of Options Exercisable		244
Options exercisable, Weighted-Average Exercise Price (in dollars per share)		$ 1.85
Options exercisable, aggregate intrinsic value		$ 1,101
Options exercisable, Weighted average remaining contractual term		5 years 6 months
Vested and expected to vest (in shares)		471
Vested and expected to vest, Weighted Average Exercise Price (in dollars per share)		$ 1.82
Vested and expected to vest, Aggregate Intrinsic Value		$ 571
Vested and expected to vest, remaining contractual term (in years)		5 years 4 months 24 days
General and administrative	$ 1,172	$ 6,262	$ 3,734	$ 619
Stock options
Stock Option Activity and Weighted-Average Exercise Price
General and administrative	$ 45	177	$ 182	$ 61
Compensation expense for unvested stock options		$ 14,400
Minimum | Stock options
Stock Option Activity and Weighted-Average Exercise Price
Weighted average period for unvested stock options		2 months 12 days
Maximum | Stock options
Stock Option Activity and Weighted-Average Exercise Price
Weighted average period for unvested stock options		1 year 8 months 12 days