FINANCING RECEIVABLES - Components of Receivables (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Less: allowance for expected credit losses	$ (879)	$ (722)	$ (1,489)
Total financing receivables	11,752	13,719
Long-Term Financing Arrangement
Financing Receivable, Recorded Investment, Past Due [Line Items]
Long-term financing arrangements, gross	13,704	15,659
Less: allowance for expected credit losses	(875)	(716)
Less: unearned income	(1,147)	(1,339)
Total financing receivables	$ 11,682	$ 13,604