EARNINGS PER SHARE - Earnings per share attributable to common stock and restricted shares of common stock (Details 1) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Line Items]
Basic earnings per share (in dollars per share)	$ 0.08	$ 0.05	$ 0.28	$ 0.19
Common stock
Earnings Per Share [Line Items]
Basic earnings per share (in dollars per share)	0.08	0.05	0.28	0.19
Restricted shares of common stock
Earnings Per Share [Line Items]
Basic earnings per share (in dollars per share)	$ 0.08	$ 0.05	$ 0.27	$ 0.18