DERIVATIVE FINANCIAL INSTRUMENTS - Derivative Warrant Issuances (Details) - Derivative - Warrants	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Shares
Outstanding, beginning balance (in shares) | shares	1,159,424
Issued (in shares) | shares	0
Canceled (in shares) | shares	554
Exercised (in shares) | shares	1,158,870
Outstanding, ending balance (in shares) | shares	0
Weighted Average Exercise Price
Outstanding, beginning balance (in USD per share)	$ 7.86
Issued (in USD per share)	0
Cancelled (in USD per share)	5.99
Exercised (in USD per share)	7.88
Outstanding, ending balance (in USD per share)	0
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in USD per share)	4.15
Issued (in USD per share)	0
Cancelled (in USD per share)	3.33
Exercised (in USD per share)	4.15
Outstanding, Ending Balance (in USD per share)	$ 0