SHARE-BASED COMPENSATION (Details)	6 Months Ended
	Jun. 30, 2018 $ / shares shares
2007 EIP
SHARE-BASED COMPENSATION
Number of shares of common stock reserved for grants	691,051
Common stock issued under share-based compensation plan	253,659
2012 EIP
SHARE-BASED COMPENSATION
Number of shares of common stock reserved for grants	1,200,000
Common stock issued under share-based compensation plan	635,089
2015 EIP
SHARE-BASED COMPENSATION
Number of shares of common stock reserved for grants	1,100,000
Common stock issued under share-based compensation plan	302,360
Stock Options
SHARE-BASED COMPENSATION
Expiration term	10 years
Summary of the stock option activity
Outstanding at the beginning of the period (in shares)	67,188
Granted (in shares)	0
Expired (in shares)	(4,750)
Outstanding at the end of the period (in shares)	62,438
Exercisable (in shares)	62,438
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 24.65
Expired (in dollars per share) | $ / shares	111.42
Outstanding at the end of the period (in dollars per share) | $ / shares	18.05
Exercisable (in dollars per share) | $ / shares	$ 18.05
Stock Options | 2007 EIP
SHARE-BASED COMPENSATION
Number of shares reserved	25,233
Stock Options | 2012 EIP
SHARE-BASED COMPENSATION
Number of shares reserved	37,205
Stock Options | Minimum
SHARE-BASED COMPENSATION
Vesting term	1 year
Stock Options | Maximum
SHARE-BASED COMPENSATION
Vesting term	5 years
RSU | 2007 EIP
SHARE-BASED COMPENSATION
Number of shares reserved	0
RSU | 2015 EIP
SHARE-BASED COMPENSATION
Number of shares reserved	879,940
RSU | Minimum
SHARE-BASED COMPENSATION
Vesting term	1 year
RSU | Maximum
SHARE-BASED COMPENSATION
Vesting term	5 years