PREFERRED STOCK AND TEMPORARY EQUITY -Series C Convertible Preferred Stock Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 29, 2016	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)		$ 0.001
Series C Preferred
Class of Stock [Line Items]
Preferred stock, shares issued	44,000	0	31,568
Proceeds from issuance of preferred stock	$ 4
Preferred stock, par value (in dollars per share)	$ 100	$ 0.001	$ 0.001
Liquidation preference per share (in dollars per share)	100
Conversion terms (in dollars per share)	$ 1.00
Number of common shares issued for each convertible preferred share (in shares)	100
Assumed conversion price (in dollars per share)	$ 1.05
Conversion terms, beneficial ownership limitation (as a percent)	4.999%
Beneficial ownership limitation, notice period	61 days
Maximum | Series C Preferred
Class of Stock [Line Items]
Conversion terms, beneficial ownership limitation (as a percent)	9.999%