STOCK BASED COMPENSATION - Nonvested stock option (Details) - Stock option - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Number of shares
Nonvested at December 31, 2015 (in shares)	565,798
Granted (in shares)	182,118	176,093
Vested (in shares)	(132,184)
Forfeited (in shares)	(25,956)
Nonvested at December 31, 2016 (in shares)	589,776	565,798
Weighted average grant date fair value
Nonvested at December 31, 2015 (in dollars per shares)	$ 2.61
Granted (in dollars per shares)	2.94
Vested (in dollars per shares)	2.41
Forfeited (in dollars per shares)	2.18
Nonvested at December 31, 2016 (in dollars per shares)	$ 2.73	$ 2.61