STOCKHOLDERS' EQUITY - Schedule of Series E Preferred Stock Issued Prices and Proceeds Presented Net of Underwriting Fees and Other Costs (Details) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Net Proceeds		$ 1,898,000	$ 13,266,000	$ 18,180,000
Cumulative Redeemable Preferred Stock, Series E [Member]
Class of Stock [Line Items]
Net Proceeds	$ 164,300,000
Continuous Offering Program [Member] | Cumulative Redeemable Preferred Stock, Series E [Member]
Class of Stock [Line Items]
Shares		78,000	538,000	757,000
Net Issue Price		$ 24.23	$ 24.61	$ 24.01
Net Proceeds		$ 1,887,000	$ 13,236,000	$ 18,180,000