FAIR VALUE MEASUREMENT (The liability component was valued based on the Income Approach) (Details) - 2021 Notes [Member] - Fair Value, Inputs, Level 3 [Member] - $ / shares		1 Months Ended	12 Months Ended
	Dec. 07, 2016	Jul. 24, 2017	Dec. 31, 2018
Stock price (USD)			$ 0.31
Expected term	4 years 11 months 8 days	4 years 3 months 25 days	2 years 10 months 17 days
Risk free rate	1.86%	1.74%	2.44%
Volatility	54.12%	63.79%	75.94%
Yield	13.98%	11.56%	13.34%