Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Document Fiscal Year Focus	2013
Other expense (income) [Abstract]
Provision for impairment	$ 6,000	$ 74,816	$ 15,883
Equity in income of investments in real estate partnerships (note 4)	31,718	23,807	9,643
Federal Income Tax Expense (Benefit), Continuing Operations	0	13,224	2,994
Parent Company [Member]
Revenues:
Minimum rent	353,833	340,940	332,027
Percentage rent	3,583	3,323	2,989
Recoveries from tenants and other income	106,494	103,155	101,453
Total revenues	489,007	473,929	470,449
Management Transaction And Other Fees	25,097	26,511	33,980
Operating expenses:
Depreciation and amortization	130,630	119,008	120,803
Operating and maintenance	71,018	66,687	68,501
General and administrative	61,234	61,700	56,117
Real estate taxes	53,726	52,911	52,039
Other expenses	8,079	7,187	6,516
Total operating expenses	324,687	307,493	303,976
Other expense (income) [Abstract]
Interest Expense	108,966	112,129	123,645
Provision for impairment	6,000	20,316	12,466
Early extinguishment of debt	32	852	0
Net investment (income) loss from deferred compensation plan, including unrealized (gains) losses of $(2,231), $(888), and $567 in 2013, 2012, and 2011, respectively (note 13)	(3,257)	(2,057)	206
Total other expense (income)	111,741	131,240	136,317
Income before equity in income of investments in real estate partnerships	52,579	35,196	30,156
Equity in income of investments in real estate partnerships (note 4)	31,718	23,807	9,643
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	84,297	59,003	39,799
Federal Income Tax Expense (Benefit), Continuing Operations	0	13,224	2,994
Income from continuing operations before tax	84,297	45,779	36,805
Discontinued operations, net (note 3):
Operating income (loss)	7,332	(43,583)	10,637
Gain on sale of operating properties, net	57,953	21,855	5,942
Income (loss) from discontinued operations	65,285	(21,728)	16,579
Income before gain on sale of real estate	149,582	24,051	53,384
Gain on sale of real estate	(1,703)	(2,158)	(2,404)
Net income	151,285	26,209	55,788
Noncontrolling interests:
Net Income (Loss) Attributable to Noncontrolling Interest, Preferred Unit Holders (Deprecated 2013-01-31)	0	629	(3,725)
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Nonredeemable	(276)	(106)	(103)
Noncontrolling Interest in Net Income (Loss) Limited Partnerships, Nonredeemable	(1,205)	(865)	(590)
Income attributable to noncontrolling interests	(1,481)	(342)	(4,418)
Net income attributable to the Company	149,804	25,867	51,370
Preferred stock dividends	(21,062)	(32,531)	(19,675)
Net income (loss) attributable to common stockholders	128,294	(7,236)	31,080
Net income (loss) attributable to common stockholders	128,742	(6,664)	31,695
Income (loss) per common share - basic (note 14):
Continuing operations (in dollars per share)	$ 0.69	$ 0.16	$ 0.16
Discontinued operations (in dollars per share)	$ 0.71	$ (0.24)	$ 0.19
Net income attributable to common stockholders (in dollars per share)	$ 1.40	$ (0.08)	$ 0.35
Income (loss) per common share - diluted (note 14):
Continuing operations (in dollars per share)	$ 0.69	$ 0.16	$ 0.16
Discontinued operations (in dollars per share)	$ 0.71	$ (0.24)	$ 0.19
Net income (loss) attributable to common stockholders (in dollars per share)	$ 1.40	$ (0.08)	$ 0.35
Partnership Interest [Member]
Revenues:
Minimum rent	353,833	340,940	332,027
Percentage rent	3,583	3,323	2,989
Recoveries from tenants and other income	106,494	103,155	101,453
Total revenues	489,007	473,929	470,449
Management Transaction And Other Fees	25,097	26,511	33,980
Operating expenses:
Depreciation and amortization	130,630	119,008	120,803
Operating and maintenance	71,018	66,687	68,501
General and administrative	61,234	61,700	56,117
Real estate taxes	53,726	52,911	52,039
Other expenses	8,079	7,187	6,516
Total operating expenses	324,687	307,493	303,976
Other expense (income) [Abstract]
Interest Expense	108,966	112,129	123,645
Provision for impairment	6,000	20,316	12,466
Early extinguishment of debt	32	852	0
Net investment (income) loss from deferred compensation plan, including unrealized (gains) losses of $(2,231), $(888), and $567 in 2013, 2012, and 2011, respectively (note 13)	(3,257)	(2,057)	206
Total other expense (income)	111,741	131,240	136,317
Income before equity in income of investments in real estate partnerships	52,579	35,196	30,156
Equity in income of investments in real estate partnerships (note 4)	31,718	23,807	9,643
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	84,297	59,003	39,799
Federal Income Tax Expense (Benefit), Continuing Operations	0	13,224	2,994
Income from continuing operations before tax	84,297	45,779	36,805
Discontinued operations, net (note 3):
Operating income (loss)	7,332	(43,583)	10,637
Gain on sale of operating properties, net	57,953	21,855	5,942
Income (loss) from discontinued operations	65,285	(21,728)	16,579
Income before gain on sale of real estate	149,582	24,051	53,384
Gain on sale of real estate	(1,703)	(2,158)	(2,404)
Net income	151,285	26,209	55,788
Noncontrolling interests:
Noncontrolling Interest in Net Income (Loss) Limited Partnerships, Nonredeemable	(1,205)	(865)	(590)
Income attributable to noncontrolling interests	(1,205)	(865)	(590)
Net income attributable to the Company	150,080	25,344	55,198
Preferred unit distributions	(21,062)	(31,902)	(23,400)
Net (loss) income attributable to common unit holders	129,018	(6,558)	31,798
Net income (loss) attributable to common stockholders	$ 128,570	$ (7,130)	$ 31,183
Income (loss) per common share - basic (note 14):
Continuing operations (in dollars per share)	$ 0.69	$ 0.16	$ 0.16
Discontinued operations (in dollars per share)	$ 0.71	$ (0.24)	$ 0.19
Net income attributable to common unit holders (in dollars per share)	$ 1.40	$ (0.08)	$ 0.35
Income (loss) per common share - diluted (note 14):
Continuing operations (in dollars per share)	$ 0.69	$ 0.16	$ 0.16
Discontinued operations (in dollars per share)	$ 0.71	$ (0.24)	$ 0.19
Net Income (Loss), Per Outstanding Limited Partnership Unit, Diluted	$ 1.40	$ (0.08)	$ 0.35