Consolidated Statements of Beneficiaries' Equity (USD $) In Thousands, except Share data	Total	7.375% Series D Preferred Shares	Common Stock	Treasury Stock	Deferred Compensation Payable in Common Stock	Common Shares in Grantor Trust	Additional Paid-in Capital	Cumulative Earnings	Accumulated Other Comprehensive Income (Loss)	Cumulative Distributions	Non-Controlling Interests
Beginning Balance at Dec. 31, 2008	$ 1,722,498	$ 43	$ 882	$ (14,121)	$ 6,274	$ (6,274)	$ 2,351,428	$ 498,716	$ (17,005)	$ (1,150,406)	$ 52,961
Beginning Balance, shares at Dec. 31, 2008		4,300,000	88,610,053	451,116	215,742
Net income (loss)	8,089							8,026			63
Comprehensive income	7,086								7,376		(290)
Issuance of Common Shares of Beneficial Interest	242,323		403				241,920
Issuance of Common Shares of Beneficial Interest, shares			40,250,000
Bonus Share Issuance	123			1,228				(1,105)
Bonus Share Issuance, shares				(36,826)
Vesting of Restricted Stock	(212)		2	2,960	56	(56)	(852)	(2,322)
Vesting of Restricted Stock, shares				(86,172)	(8,971)
Restricted Stock Amortization	3,286						3,286
Restricted Performance Units Amortization	288						288
Conversion of LP Units to Common Shares	0			432				(178)			(254)
Conversion of LP Units to Common Shares, shares				(7,513)
Share Issuance from/to Deferred Compensation Plan	131			1,830	(816)	816	(29)	(1,670)
Share Issuance from/to Deferred Compensation Plan, shares			(3,796)	(54,854)	26,092
Share Choice Plan Issuance Shares			(7,081)
Share Choice Plan Issuance	(46)		(1)				(45)
Stock Option Amortization	602						602
Outperformance Plan Amortization	927						927
Trustee Fees Paid in Shares	152			466	35	(35)		(314)
Trustee Fees Paid in Shares, shares				(13,987)	(4,895)
Other — consolidated real estate ventures	34										34
Other Activity	678						187		491
Adjustment to Non-controlling Interest	0						12,709	231			(12,940)
Preferred Share distributions	(7,992)									(7,992)
Distributions declared ($0.60), ($0.60), and ($0.45) per share in 2011, 2010 and 2009, respectively	(56,227)									(54,961)	(1,266)
Ending Balance at Dec. 31, 2009	1,921,740	43	1,286	(7,205)	5,549	(5,549)	2,610,421	501,384	(9,138)	(1,213,359)	38,308
Ending Balance, shares at Dec. 31, 2009		4,300,000	128,849,176	251,764	255,700
Net income (loss)	(17,606)							(17,074)			(532)
Comprehensive income	7,348								7,193		155
Issuance of Common Shares of Beneficial Interest	71,981		57				71,924
Issuance of Common Shares of Beneficial Interest, shares			5,742,268
Equity issuance costs	(1,214)						(1,214)
Noncontrolling Interest, Increase from Equity Issuance or Sale of Parent Equity Interest	77,732										77,732
Bonus Share Issuance	369			871	369	(369)		(502)
Bonus Share Issuance, shares				(32,607)	(32,607)
Vesting of Restricted Stock	(227)			2,304	103	(103)	(1,114)	(1,417)
Vesting of Restricted Stock, shares				(76,598)	(8,989)
Restricted Stock Amortization	3,483						3,483
Restricted Performance Units Amortization	965						965
Conversion of LP Units to Common Shares				732				(266)			(466)
Conversion of LP Units to Common Shares, shares				(17,468)
Share Issuance from/to Deferred Compensation Plan	0				(282)	282
Share Issuance from/to Deferred Compensation Plan, shares			(2,409)		(9,035)
Stock Option Amortization	1,131						1,131
Outperformance Plan Amortization	380						380
Trustee Fees Paid in Shares	99			224	35	(35)		(125)
Trustee Fees Paid in Shares, shares				(8,412)	(3,020)
Exercise of Stock Options	37						37
Exercise of Stock Options, shares			12,761
Adjustment to Non-controlling Interest	0						(14,796)				14,796
Cumulative effect of accounting change for variable interest entities	1,401							1,439			(38)
Preferred Share distributions	(7,992)									(7,992)
Distributions declared ($0.60), ($0.60), and ($0.45) per share in 2011, 2010 and 2009, respectively	(81,853)									(80,170)	(1,683)
Ending 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
Ending Balance, shares at Dec. 31, 2010		4,300,000	134,601,796	116,679	291,281
Net income (loss)	(4,715)							(4,500)			(215)
Comprehensive income	(4,346)								(4,134)		(212)
Issuance of Common Shares of Beneficial Interest	8,272		7				8,265
Issuance of Common Shares of Beneficial Interest, shares	679,285		679,285
Equity issuance costs	(377)						(345)				(32)
Bonus Share Issuance	6			12	6	(6)		(6)
Bonus Share Issuance, shares				(463)	(463)
Vesting of Restricted Stock	(350)		1	3,062			(1,818)	(1,595)
Vesting of Restricted Stock, shares			(85,248)	(116,216)	(9,043)
Restricted Stock Amortization	2,937						2,937
Restricted Performance Units Amortization	1,679						1,679
Conversion of LP Units to Common Shares	0		72				85,966				(86,038)
Conversion of LP Units to Common Shares, shares			(7,204,104)
Share Issuance from/to Deferred Compensation Plan	(16)				(149)	149	(16)
Share Issuance from/to Deferred Compensation Plan, shares			(845)		(8,141)
Share Choice Plan Issuance Shares			(1,684)
Share Choice Plan Issuance	(55)						(55)
Stock Option Amortization	1,487						1,487
Outperformance Plan Amortization	123						123
Trustee Fees Paid in Shares	32						32
Trustee Fees Paid in Shares, shares			(2,672)
Exercise of Stock Options	350		1				349
Exercise of Stock Options, shares	120,180		120,179
Adjustment to Non-controlling Interest	0						6,376				(6,376)
Preferred Share distributions	(7,992)									(7,992)
Distributions declared ($0.60), ($0.60), and ($0.45) per share in 2011, 2010 and 2009, respectively	(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
Ending Balance, shares at Dec. 31, 2011		4,300,000	142,690,755	0	292,646