STOCKHOLDERS' EQUITY - Summary of restricted shares (Details) - Restricted stock [Member]	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Equity Incentive Plans Restricted Stock Activity [Line Items]
Number of Shares, Outstanding at Beginning Balance | shares	7,091,789
Number of Shares, Granted | shares	774,300
Number of Shares, Vested | shares	(527,237)
Number of Shares, Forfeited | shares	(10,000)
Number of Shares, Outstanding at Ending Balance | shares	7,328,852
Weighted Average Grant Date Fair Value, Outstanding at Beginning Balance | $ / shares	$ 7.78
Weighted Average Grant Date Fair Value, Granted | $ / shares	10.16
Weighted Average Grant Date Fair Value, Vested | $ / shares	7.27
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	7.54
Weighted Average Grant Date Fair Value, Outstanding at Ending Balance | $ / shares	$ 8.07