EARNINGS PER SHARE - Earnings per share attributable to common stock and restricted shares (Details 2) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Basic (loss) earnings per share
Basic (in dollars per share)	$ (0.16)	$ 0.29	$ (0.12)	$ 0.48
Common Stock
Basic (loss) earnings per share
Basic (in dollars per share)	(0.16)	0.29	(0.12)	0.48
Restricted shares of common stock
Basic (loss) earnings per share
Basic (in dollars per share)	$ (0.13)	$ 0.28	$ (0.13)	$ 0.44