Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other expense (income) [Abstract]
Provision for impairment	$ 74,800	$ 15,900	$ 23,900
Equity in income (loss) of investments in real estate partnerships (note 4)	23,807	9,643	(12,884)
Income Tax Expense (Benefit), Continuing Operations	(13,224)	(2,994)	1,333
Parent Company [Member]
Revenues:
Minimum rent	359,350	350,223	332,159
Percentage rent	3,327	2,996	2,540
Recoveries from tenants and other income	107,732	105,899	104,092
Management, transaction, and other fees	26,511	33,980	29,400
Total revenues	496,920	493,098	468,191
Operating expenses:
Depreciation and amortization	126,808	128,963	118,398
Operating and maintenance	69,900	71,707	67,514
General and administrative	61,700	56,117	61,505
Real estate taxes	55,604	54,622	52,386
Other expenses	7,246	6,719	6,297
Total operating expenses	321,258	318,128	306,100
Other expense (income) [Abstract]
Interest Expense	112,129	123,645	125,287
Provision for impairment	74,816	12,424	19,886
Early extinguishment of debt	852	0	4,243
Net investment (income) loss from deferred compensation plan, including unrealized (gains) losses of $(888), $567, and $(1,342) in 2012, 2011, and 2010, respectively (note 13)	(2,057)	206	(1,982)
Total other expense (income)	185,740	136,275	147,434
(Loss) income before equity in income (loss) of investments in real estate partnerships	(10,078)	38,695	14,657
Equity in income (loss) of investments in real estate partnerships (note 4)	23,807	9,643	(12,884)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	13,729	48,338	1,773
Income Tax Expense (Benefit), Continuing Operations	(13,224)	(2,994)	1,333
Income from continuing operations before tax	505	45,344	3,106
Discontinued operations, net (note 3):
Operating income	1,691	2,098	1,325
Gain on sale of operating properties, net	21,855	5,942	7,577
Income from discontinued operations	23,546	8,040	8,902
Income before gain on sale of real estate	24,051	53,384	12,008
Gain on sale of real estate	(2,158)	(2,404)	(993)
Net income	26,209	55,788	13,001
Noncontrolling interests:
Preferred units	629	(3,725)	(3,725)
Exchangeable operating partnership units	(106)	(103)	(84)
Limited partners’ interests in consolidated partnerships	(865)	(590)	(376)
Income attributable to noncontrolling interests	(342)	(4,418)	(4,185)
Net income attributable to the Company	25,867	51,370	8,816
Preferred stock dividends	(32,531)	(19,675)	(19,675)
Net (loss) income attributable to common stockholders	(6,664)	31,695	(10,859)
(Loss) income per common share - basic (note 14):
Continuing operations (in dollars per share)	$ (0.34)	$ 0.26	$ (0.25)
Discontinued operations (in dollars per share)	$ 0.26	$ 0.09	$ 0.11
Net income attributable to common stockholders (in dollars per share)	$ (0.08)	$ 0.35	$ (0.14)
(Loss) income per common share - diluted (note 14):
Continuing operations (in dollars per share)	$ (0.34)	$ 0.26	$ (0.25)
Discontinued operations (in dollars per share)	$ 0.26	$ 0.09	$ 0.11
Net income (loss) attributable to common stockholders (in dollars per share)	$ (0.08)	$ 0.35	$ (0.14)
Partnership Interest [Member]
Revenues:
Minimum rent	359,350	350,223	332,159
Percentage rent	3,327	2,996	2,540
Recoveries from tenants and other income	107,732	105,899	104,092
Management, transaction, and other fees	26,511	33,980	29,400
Total revenues	496,920	493,098	468,191
Operating expenses:
Depreciation and amortization	126,808	128,963	118,398
Operating and maintenance	69,900	71,707	67,514
General and administrative	61,700	56,117	61,505
Real estate taxes	55,604	54,622	52,386
Other expenses	7,246	6,719	6,297
Total operating expenses	321,258	318,128	306,100
Other expense (income) [Abstract]
Interest Expense	112,129	123,645	125,287
Provision for impairment	74,816	12,424	19,886
Early extinguishment of debt	852	0	4,243
Net investment (income) loss from deferred compensation plan, including unrealized (gains) losses of $(888), $567, and $(1,342) in 2012, 2011, and 2010, respectively (note 13)	(2,057)	206	(1,982)
Total other expense (income)	185,740	136,275	147,434
(Loss) income before equity in income (loss) of investments in real estate partnerships	(10,078)	38,695	14,657
Equity in income (loss) of investments in real estate partnerships (note 4)	23,807	9,643	(12,884)
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	13,729	48,338	1,773
Income Tax Expense (Benefit), Continuing Operations	(13,224)	(2,994)	1,333
Income from continuing operations before tax	505	45,344	3,106
Discontinued operations, net (note 3):
Operating income	1,691	2,098	1,325
Gain on sale of operating properties, net	21,855	5,942	7,577
Income from discontinued operations	23,546	8,040	8,902
Income before gain on sale of real estate	24,051	53,384	12,008
Gain on sale of real estate	(2,158)	(2,404)	(993)
Net income	26,209	55,788	13,001
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(865)	(590)	(376)
Income attributable to noncontrolling interests	(865)	(590)	(376)
Net income attributable to the Company	25,344	55,198	12,625
Preferred unit distributions	(31,902)	(23,400)	(23,400)
Net (loss) income attributable to common unit holders	$ (6,558)	$ 31,798	$ (10,775)
(Loss) income per common share - basic (note 14):
Continuing operations (in dollars per share)	(0.34)	0.26	(0.25)
Discontinued operations (in dollars per share)	0.26	0.09	0.11
Net income attributable to common unit holders (in dollars per share)	(0.08)	0.35	(0.14)
(Loss) income per common share - diluted (note 14):
Continuing operations (in dollars per share)	(0.34)	0.26	(0.25)
Discontinued operations (in dollars per share)	0.26	0.09	0.11
Net Income (Loss), Per Outstanding Limited Partnership Unit, Diluted	(0.08)	0.35	(0.14)