STOCKHOLDERS' EQUITY-Common stock and warrants (Details) $ / shares in Units, $ in Thousands					9 Months Ended	12 Months Ended
	Oct. 08, 2019 series $ / shares shares	Oct. 02, 2019 $ / shares	Feb. 09, 2018 USD ($) $ / shares shares	Apr. 06, 2017 shares	Oct. 01, 2019 USD ($)	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2019 $ / shares shares	Aug. 02, 2019	Sep. 09, 2016 $ / shares shares
Stockholders' equity
Shares issued	16,200,000		9,200,000	55,200,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001		$ 0.0001			$ 0.0001	$ 0.0001
Share price (in dollars per share) | $ / shares		$ 19.74	$ 6.90
Proceeds from Issuance of Common Stock | $			$ 60,400		$ 155,929	$ 63,480
Number of warrants issued									4,700,000
Equivalent number shares of the warrants									4,700,000
Annualized Rate Of Increase To The Strike Price Of Warrants Issued	6.75	6.75
Exercise price (in dollars per share) | $ / shares									$ 14.04
Warrant term (in years)	3 years
Authorized shares of capital stock, after amendment of certificate of incorporation	101,000,000
Authorized shares of common stock, after amendment of certificate of incorporation	100,000,000					1,000,000,000	100,000,000
Number of series of warrants | series	3
Number of shares of common stock that can be purchased from warrants	1
Series A Warrants
Stockholders' equity
Warrants issued	1,798,322
Exercise price (in dollars per share) | $ / shares	$ 40.17						$ 40.51
Series B Warrants
Stockholders' equity
Warrants issued	2,247,985
Exercise price (in dollars per share) | $ / shares	$ 48.28						48.71
Series C Warrants
Stockholders' equity
Warrants issued	2,890,271
Exercise price (in dollars per share) | $ / shares	$ 60.45						$ 61.02
The Restructuring Support Agreement
Stockholders' equity
Warrant term (in years)								3 years
Convertible Preferred stock
Stockholders' equity
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001
Authorized shares of preferred stock, after amendment of certificate of incorporation	1,000,000