Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Parent Company [Member]
Revenues
Minimum rent	$ 92,365	$ 87,173
Percentage rent	1,160	907
Recoveries from tenants and other income	26,714	28,390
Management, transaction, and other fees	7,150	7,858
Total revenues	127,389	124,328
Operating Expenses
Depreciation and amortization	32,841	34,499
Operating and maintenance	18,594	18,984
General and administrative	16,122	16,953
Real estate taxes	15,289	14,357
Other expenses	1,589	(321)
Total operating expenses	84,435	84,472
Other expense (income):
Interest expense, net of interest income of $535 and $601 in 2012 and 2011, respectively	28,958	30,865
Gain on sale of real estate	(1,834)	0
Net investment income from deferred compensation plan, including $1,224 and $643 of unrealized gains	(1,528)	(745)
Total other expense (income)	25,596	30,120
Income before equity in income (loss) of investments in real estate partnerships	17,358	9,736
Equity in income (loss) of investments in real estate partnerships	2,966	(2,725)
Income from continuing operations	20,324	7,011
Discontinued operations, net:
Operating income	110	1,119
Gain on sale of operating properties, net	6,301	0
Income from discontinued operations	6,411	1,119
Net income	26,735	8,130
Noncontrolling interests:
Preferred units	629	(931)
Exchangeable operating partnership units	(54)	(13)
Limited partners' interest in consolidated partnerships	(192)	(82)
Loss (income) attributable to noncontrolling interests	383	(1,026)
Net income attributable to controlling interests	27,118	7,104
Preferred stock dividends	(13,937)	(4,919)
Net income attributable to common stockholders	13,181	2,185
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.07	$ 0.01
Discontinued operations (in dollars per share)	$ 0.07	$ 0.01
Net income attributable to common stockholders (in dollars per share)	$ 0.14	$ 0.02
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.07	$ 0.01
Discontinued operations (in dollars per share)	$ 0.07	$ 0.01
Net income attributable to common stockholders (in dollars per share)	$ 0.14	$ 0.02
Partnership Interest [Member]
Revenues
Minimum rent	92,365	87,173
Percentage rent	1,160	907
Recoveries from tenants and other income	26,714	28,390
Management, transaction, and other fees	7,150	7,858
Total revenues	127,389	124,328
Operating Expenses
Depreciation and amortization	32,841	34,499
Operating and maintenance	18,594	18,984
General and administrative	16,122	16,953
Real estate taxes	15,289	14,357
Other expenses	1,589	(321)
Total operating expenses	84,435	84,472
Other expense (income):
Interest expense, net of interest income of $535 and $601 in 2012 and 2011, respectively	28,958	30,865
Gain on sale of real estate	(1,834)	0
Net investment income from deferred compensation plan, including $1,224 and $643 of unrealized gains	(1,528)	(745)
Total other expense (income)	25,596	30,120
Income before equity in income (loss) of investments in real estate partnerships	17,358	9,736
Equity in income (loss) of investments in real estate partnerships	2,966	(2,725)
Income from continuing operations	20,324	7,011
Discontinued operations, net:
Operating income	110	1,119
Gain on sale of operating properties, net	6,301	0
Income from discontinued operations	6,411	1,119
Net income	26,735	8,130
Noncontrolling interests:
Limited partners' interest in consolidated partnerships	(192)	(82)
Loss (income) attributable to noncontrolling interests	(192)	(82)
Net income attributable to controlling interests	26,543	8,048
Preferred unit distributions	(13,308)	(5,850)
Net income attributable to common unit holders	$ 13,235	$ 2,198
Income per common share/unit - basic:
Continuing operations (in dollars per share)	0.07	0.01
Discontinued operations (in dollars per share)	0.07	0.01
Net income attributable to common unit holders (in dollars per share)	0.14	0.02
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	0.07	0.01
Discontinued operations (in dollars per share)	0.07	0.01
Net income attributable to common unit holders (in dollars per share)	0.14	0.02
Net Income (Loss), Per Outstanding Limited Partnership Unit, Diluted	0.14	0.02