SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Common Shares Excluded from EPS Calculations (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	3,435,390	2,668,331
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	1,632,495	55,360
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from the calculation of EPS (in shares)	1,802,895	1,347,500
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
Warrants to purchase 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	9,005