Consolidated Statements of Beneficiaries' Equity (USD $) In Thousands, except Share data	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Deferred Compensation, Share-based Payments [Member]	Common Stock In Grantor Trust [Member]	Cumulative Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Distributions [Member]	Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2012	$ 1,773,516	$ 40	$ 1,434	$ 2,780,194	$ 5,352	$ (5,352)	$ 479,734	$ (15,918)	$ (1,493,206)	$ 21,238
Beginning Balance, Shares at Dec. 31, 2012		4,000,000	143,538,733		290,745
Net income (loss)	11,099						11,011			88
Comprehensive Income (Loss)	11,451							11,317		134
Stock Issued During Period, Shares, New Issues			12,650,000
Stock Issued During Period, Value, New Issues	182,034		127	181,907
Equity Issuance Costs	(380)			(380)
Stock Issued During Period, Shares, Conversion of Units			81,998
Bonus Share Issuance, Shares			27,918
Stock Issued During Period, Value, Conversion of Units	0		1	1,240						(1,241)
Bonus Share Issuance, Value	361			361
Share Based Compensation Activity, Shares			341,591		7,050
Share Based Compensation Activity, Value	5,219		3	5,207			9
Share Issuance from/to Deferred Compensation Plan, Shares			22,404		17,958
Share issuance from/to Deferred Compensation Plan, Value	0				164	(164)
Adjustments to Non-controlling Interest	0			(739)						739
Preferred Share distributions	(3,450)								(3,450)
Distributions declared ($0.30 per share)	(45,781)								(45,240)	(541)
Ending Balance at Jun. 30, 2013	1,934,069	40	1,565	2,967,790	5,516	(5,516)	490,754	(4,601)	(1,541,896)	20,417
Ending Balance, Shares at Jun. 30, 2013		4,000,000	156,662,644		315,753
Beginning Balance at Dec. 31, 2013	1,921,435	40	1,566	2,971,596	5,407	(5,407)	522,528	(2,995)	(1,592,515)	21,215
Beginning Balance, Shares at Dec. 31, 2013		4,000,000	156,731,993		312,280
Net income (loss)	(71)						(20)			(51)
Comprehensive Income (Loss)	(3,145)							(3,110)		(35)
Equity Issuance Costs	(60)			(60)
Share Based Compensation Activity, Shares			279,913
Share Based Compensation Activity, Value	3,629		5	3,612			12
Share Issuance from/to Deferred Compensation Plan, Shares			79,077		74,808
Share issuance from/to Deferred Compensation Plan, Value	(90)			(90)	896	(896)
Adjustments to Non-controlling Interest	0			12						(12)
Preferred Share distributions	(3,450)								(3,450)
Distributions declared ($0.30 per share)	(47,806)								(47,276)	(530)
Ending Balance at Jun. 30, 2014	$ 1,870,442	$ 40	$ 1,571	$ 2,975,070	$ 6,303	$ (6,303)	$ 522,520	$ (6,105)	$ (1,643,241)	$ 20,587
Ending Balance, Shares at Jun. 30, 2014		4,000,000	157,090,983		387,088