SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred commission cost (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Deferred costs - current	$ 87	$ 103
Deferred costs - noncurrent	28	34
Accounting Standards Update 2014-09 [Member]
Deferred costs - current	87	103
Deferred costs - noncurrent	28	34
Total deferred costs	$ 115	$ 137