Beneficiaries Equity of the Parent Company (Textual) (Details) - USD ($)		3 Months Ended		12 Months Ended
	Mar. 09, 2016	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Jul. 22, 2015	Nov. 05, 2013
Class of Stock [Line Items]
Distributions payable		$ 28,295,000		$ 28,249,000
Preferred Stock, Dividend Rate, Percentage		6.90%		6.90%
Dividends, Preferred Stock		$ 1,725,000	$ 1,725,000
Shares Authorized For Equity Offering Program						16,000,000
Authorized Amount					$ 100,000,000
Number of Shares Authorized to be Repurchased					539,200
Repurchased and Retired, Shares		5,209,437
Share Price		$ 12.90
Repurchased and Retired, Value		$ 67,300,000
Shares repurchased		0	0
Common shares price per share		$ 0.01		$ 0.01
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage		6.90%
Preferred Stock, Liquidation Preference Per Share		$ 25.00
Offering Program [Member]
Class of Stock [Line Items]
Remaining Shares Available For Sales		16,000,000
Offering Program [Member] | Maximum [Member]
Class of Stock [Line Items]
Fees and Commissions Percentage		2.00%
Dividend Declared [Member]
Class of Stock [Line Items]
Dividends Payable, Amount Per Share	$ 0.15
Dividend Paid [Member]
Class of Stock [Line Items]
Distributions payable		$ 26,600,000
Dividend Paid [Member] | Series E Preferred Stock [Member]
Class of Stock [Line Items]
Dividends, Preferred Stock	$ 1,700,000
Redeemable Common Limited Partnership Units
Class of Stock [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share		1,535,102	1,535,102