Consolidated Statements of Beneficiaries' Equity (USD $) In Thousands, except Share data	Total	Series E Preferred Stock [Member]	Common Stock	Treasury Stock	Deferred Compensation Payable in Common Shares	Common Shares in Grantor Trust	Additional Paid-in Capital	Cumulative Earnings	Accumulated Other Comprehensive Income (Loss)	Cumulative Distributions	Non-Controlling Interests	Subsidiaries [Member]	Subsidiaries [Member] Series E Preferred Stock [Member]	Subsidiaries [Member] Accumulated Other Comprehensive Income (Loss)	Subsidiaries [Member] Non-Controlling Interests	Subsidiaries [Member] Series D Preferred Stock [Member]	Subsidiaries [Member] Total partners equity [Member]	Subsidiaries [Member] Series E-linked Preferred Stock [Member]
Beginning Balance at Dec. 31, 2010	$ 1,977,774	$ 43	$ 1,343	$ (3,074)	$ 5,774	$ (5,774)	$ 2,671,217	$ 483,439	$ (1,945)	$ (1,301,521)	$ 128,272		$ 55,538	$ (2,080)	$ 0	$ 47,912	$ 1,844,919	$ 0
Beginning Balance, shares at Dec. 31, 2010		4,300,000	134,601,796	116,679	291,281								2,300,000			2,000,000		0
Net income (loss)	(4,715)							(4,500)			(215)	(4,715)					(4,715)
Comprehensive income (loss)	(4,346)								(4,134)		(212)	(4,346)		(4,346)			(4,346)
Issuance of Common Shares of Beneficial Interest, shares			679,285
Issuance of Common Shares of Beneficial Interest	8,272		7				8,265
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(377)						(345)				(32)
Conversion of LP Units to Common Shares	0		72				85,966				(86,038)						86,038
Conversion of LP Units to Common Shares, shares			7,204,104
Bonus Share Issuance, shares				(463)	463
Bonus Share Issuance	6			12	6	(6)		(6)									6
Vesting of Restricted Shares, shares			85,248	(116,216)	9,043
Vesting of Restricted Shares, Value	(350)		1	3,062			(1,818)	(1,595)									(352)
Restricted Share Amortization	2,937						2,937										2,937
Restricted Performance Units Amortization	1,679						1,679										1,679
Exercise of Stock Options, shares			120,179
Exercise of Stock Options	350		1				349										350
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition							1,487
Share Issuance from/to Deferred Compensation Plan, shares			(845)		(8,141)
Share Issuance from/to Deferred Compensation Plan	(16)				(149)	149	(16)
Share Option Amortization	1,487																1,487
Outperformance Plan Amortization	123						123										123
Share Choice Plan Issuance Value	(55)						(55)										(55)
Share Choice Plan Issuance Shares			(1,684)
Stock Issued During Period, Shares, Other			2,672
Stock Issued During Period, Value, Other	32						32
Adjustment to Non-controlling Interest	0						6,376				(6,376)
Preferred Share distributions	(7,992)									(7,992)							(7,992)
Preferred share/unit redemption charge	0											0
Distributions declared ($0.60) per share in each of 2013, 2012, and 2011	(85,113)									(82,819)	(2,294)
Ending Balance at Dec. 31, 2011	1,889,696	43	1,424	0	5,631	(5,631)	2,776,197	477,338	(6,079)	(1,392,332)	33,105		55,538	(6,426)	0	47,912	1,851,326	0
Ending Balance, shares at Dec. 31, 2011		4,300,000	142,690,755	0	292,646								2,300,000			2,000,000		0
Net income (loss)	6,529							6,595			(66)	6,529					6,529
Comprehensive income (loss)	(10,026)								(9,839)		(187)	(10,026)		(10,026)			(10,026)
Issuance of Common Shares of Beneficial Interest, shares		4,000,000
Issuance of Common Shares of Beneficial Interest	96,850	40					96,810
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(613)						(613)										(613)
Conversion of LP Units to Common Shares	(167)		1				149	(49)			(268)						(49)
Conversion of LP Units to Common Shares, shares			20,464
Preferred Stock, Shares Issued	4,000,000											4,000,000						4,000,000
Redemption of preferred shares, Shares		(4,300,000)											(2,300,000)			(2,000,000)
Redemption of preferred shares, Value	(103,448)	(43)					(103,405)						55,538			47,912	103,450
Bonus Share Issuance, shares			35,703
Bonus Share Issuance	387						387										387
Partners' Capital Account, Redemptions	(9,741)							(4,185)			(5,556)						9,741
Vesting of Restricted Shares, shares			293,614		9,036
Vesting of Restricted Shares, Value	(1,385)		4				(1,389)										(1,385)
Restricted Share Amortization	3,271						3,271										3,271
Stock Issued During Period, Shares, Vesting of restricted performance units			272,131
Stock Issued During Period, Value, Vesting of restricted performance units	(1,495)		3				(1,498)										(1,495)
Restricted Performance Units Amortization	3,379						3,379										3,379
Restricted Stock Award, Forfeitures	35							35									(35)
Exercise of Stock Options, shares			230,294
Exercise of Stock Options	976		2				974										976
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition							1,636
Share Issuance from/to Deferred Compensation Plan, shares			(5,564)		(10,937)
Share Issuance from/to Deferred Compensation Plan	0				(279)	279
Share Option Amortization	1,636																1,636
Stock Issued During Period, Shares, Other			1,336
Stock Issued During Period, Value, Other	15						15
Adjustment to Non-controlling Interest	0						4,281				(4,281)
Preferred Share distributions	(10,405)									(10,405)							(10,405)
Preferred share/unit redemption charge	(4,052)									(4,052)		(4,052)					(4,052)
Distributions declared ($0.60) per share in each of 2013, 2012, and 2011	(87,926)									(86,417)	(1,509)
Ending Balance at Dec. 31, 2012	1,773,516	40	1,434	0	5,352	(5,352)	2,780,194	479,734	(15,918)	(1,493,206)	21,238	1,746,739	0	(16,452)		0	1,746,739	96,850
Ending Balance, shares at Dec. 31, 2012		4,000,000	143,538,733	0	290,745								0			0		4,000,000
Beginning Balance at Sep. 30, 2012
Net income (loss)	(26,698)
Preferred Stock, Shares Issued	4,000,000																	4,000,000
Ending Balance at Dec. 31, 2012	1,773,516		1,434	0	5,352	(5,352)	2,780,194	479,734	(15,918)	(1,493,206)	21,238	1,746,739		(16,452)	0		1,746,739	96,850
Ending Balance, shares at Dec. 31, 2012			143,538,733	0	290,745													4,000,000
Net income (loss)	43,189							42,777			412	43,189					43,189
Comprehensive income (loss)	13,075								12,923		152	13,075		13,075			13,075
Issuance of Common Shares of Beneficial Interest, shares			12,650,000
Issuance of Common Shares of Beneficial Interest	182,034		127				181,907
Noncontrolling Interest, Increase from Business Combination	946										946				(946)		(946)
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(744)						(744)
Conversion of LP Units to Common Shares	0		1				1,239				(1,240)						1,240
Conversion of LP Units to Common Shares, shares			81,998
Preferred Stock, Shares Issued	4,000,000											4,000,000
Redemption of preferred shares, Value																	(361)
Bonus Share Issuance, shares			27,918
Bonus Share Issuance	361						361										(902)
Partners' Capital Account, Redemptions																	(17)
Vesting of Restricted Shares, shares			147,495		7,050
Vesting of Restricted Shares, Value	(902)		2				(904)
Restricted Share Amortization	3,079						3,079										3,079
Stock Issued During Period, Shares, Vesting of restricted performance units			53,134		27,067
Stock Issued During Period, Value, Vesting of restricted performance units	(159)		1				(160)
Restricted Performance Units Amortization	4,333						4,333										4,333
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	(17)							17
Exercise of Stock Options, shares	236,318		236,318
Exercise of Stock Options	2,380		1				2,379										2,380
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition							670
Share Issuance from/to Deferred Compensation Plan, shares			(5,012)		(12,583)
Share Issuance from/to Deferred Compensation Plan	0				55	(55)
Share Option Amortization	670																670
Share Choice Plan Issuance Value																	(160)
Stock Issued During Period, Shares, Other			1,409
Stock Issued During Period, Value, Other	20						20
Adjustment to Non-controlling Interest	0						(778)				778
Preferred Share distributions	(6,900)									(6,900)							6,900
Preferred share/unit redemption charge	0											0
Distributions declared ($0.60) per share in each of 2013, 2012, and 2011	(93,480)									(92,409)	(1,071)
Ending Balance at Dec. 31, 2013	$ 1,921,435	$ 40	$ 1,566		$ 5,407	$ (5,407)	$ 2,971,596	$ 522,528	$ (2,995)	$ (1,592,515)	$ 21,215	$ 1,894,949	$ 0	$ (3,377)	$ 946	$ 0	$ 1,894,949	$ 96,850
Ending Balance, shares at Dec. 31, 2013		4,000,000	156,731,993		312,279								0			0		4,000,000