STOCK INCENTIVE PLANS - Stock Option Roll-forward (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Shares
Beginning balance (in shares)	7,193,193
Options granted (in shares)	0
Options exercised (in shares)	(205,730)
Options cancelled/forfeited/expired (in shares)	(184,391)
Ending balance (in shares)	6,803,072	7,193,193
Options exercisable (in shares)	6,564,742
Weighted average exercise price per share
Beginning balance (in dollars per share)	$ 1.87
Options granted (in dollars per share)	0
Options exercised (in dollars per share)	1.60
Options cancelled/forfeited/expired (in dollars per share)	1.73
Ending balance (in dollars per share)	1.85	$ 1.87
Options exercisable (in dollars per share)	$ 1.06
Weighted average remaining contractual life, options outstanding (in years)	6 years 14 days	6 years 5 months 12 days
Weighted average remaining contractual life, options exercisable (in years)	6 years 3 months 14 days