STOCKHOLDERS' (DEFICIT) EQUITY - Common Stock (Details)	12 Months Ended
	Dec. 31, 2019 vote $ / shares shares	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Common stock, shares issued (in shares)	106,801,409	77,456,180
Common Stock
Class of Stock [Line Items]
Common stock, shares outstanding (in shares)	106,801,409	77,456,180	34,702,565	24,531,964
Number of votes | vote	1