SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Basic and Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Warrants
Basic and Diluted Net Loss Per Share
Shares not included in computation of diluted loss per share because they are anti-dilutive	98,013,256	98,686,000
Shares Issued upon conversion of Senior Notes
Basic and Diluted Net Loss Per Share
Shares not included in computation of diluted loss per share because they are anti-dilutive	0	5,910,000
Unvested Stock Awards
Basic and Diluted Net Loss Per Share
Shares not included in computation of diluted loss per share because they are anti-dilutive	421,268	2,401,268
Stock Appreciation Rights
Basic and Diluted Net Loss Per Share
Shares not included in computation of diluted loss per share because they are anti-dilutive	909,837	938,667