NET INCOME PER COMMON SHARE - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2013
Cumulative Redeemable Preferred Stock, Series E [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Preferred stock, dividend rate	7.50%	7.50%	7.50%