SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Common Shares Excluded from EPS Calculations (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	21,387,384	2,399,800	21,387,384	2,399,800
Outstanding warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	19,556,108	349,074	19,556,108	349,074
Outstanding options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	1,578,231	625,428	1,578,231	625,428
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	253,045	0	253,045	0
Redeemable convertible preferred stock (as converted into common stock)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	0	1,256,466	0	1,256,466
Promissory notes (as converted into common stock)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	0	168,832	0	168,832