SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,661	2,044
Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	266	298
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	336	924
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	64	403
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	995	419