Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Document Fiscal Year Focus			2014
Discontinued operations, net:
Gain on sale of real estate	$ (1,691)	$ (13,127)	$ (2,406)	$ (13,127)
Parent Company [Member]
Revenues:
Minimum rent	97,778	87,006	192,314	173,151
Percentage rent	545	297	1,930	1,842
Recoveries from tenants and other income	30,316	28,263	61,357	54,190
Management, transaction, and other fees	6,253	6,741	12,572	13,502
Total revenues	134,892	122,307	268,173	242,685
Operating expenses:
Depreciation and amortization	36,023	31,082	73,929	62,199
Operating and maintenance	19,498	17,481	40,003	34,622
General and administrative	15,223	14,966	29,421	32,942
Real estate taxes	14,898	13,750	29,697	26,980
Other operating expenses	1,795	1,579	3,968	3,098
Total operating expenses	87,437	78,858	177,018	159,841
Other expense (income):
Interest expense, net of interest income of $465 and $292, and $681 and $751 for the three and six months ended June 30, 2014 and 2013, respectively	27,445	27,781	54,580	55,613
Provision for impairment	0	0	225	0
Net investment (income) loss from deferred compensation plan, including unrealized (gains) loss of ($290) and $17, and ($183) and $848 for the three and six months ended June 30, 2014 and 2013, respectively	(628)	38	(821)	(1,034)
Total other expense	26,817	27,819	53,984	54,579
Income before equity in income of investments in real estate partnerships	20,638	15,630	37,171	28,265
Equity in income of investments in real estate partnerships	8,832	6,012	16,640	11,888
Income from continuing operations	29,470	21,642	53,811	40,153
Discontinued operations, net:
Operating income	0	2,700	0	5,323
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	11,410	0	11,410
Income from discontinued operations	0	14,110	0	16,733
Income before gain on sale of real estate	29,470	35,752	53,811	56,886
Gain on sale of real estate	(1,691)	(1,717)	(2,406)	(1,717)
Net income	31,161	37,469	56,217	58,603
Noncontrolling interests:
Exchangeable operating partnership units	(53)	(70)	(95)	(109)
Limited partners’ interests in consolidated partnerships	(360)	(270)	(719)	(545)
Income attributable to noncontrolling interests	(413)	(340)	(814)	(654)
Net income attributable to the Company	30,748	37,129	55,403	57,949
Preferred stock dividends	(5,266)	(5,265)	(10,531)	(10,531)
Net income attributable to common stockholders	25,482	31,864	44,872	47,418
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.28	$ 0.19	$ 0.48	$ 0.34
Discontinued operations (in dollars per share)	$ 0.00	$ 0.16	$ 0.00	$ 0.18
Net income attributable to common stockholders (in dollars per share)	$ 0.28	$ 0.35	$ 0.48	$ 0.52
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.28	$ 0.19	$ 0.48	$ 0.34
Discontinued operations (in dollars per share)	$ 0.00	$ 0.16	$ 0.00	$ 0.18
Net income attributable to common stockholders (in dollars per share)	$ 0.28	$ 0.35	$ 0.48	$ 0.52
Partnership Interest [Member]
Revenues:
Minimum rent	97,778	87,006	192,314	173,151
Percentage rent	545	297	1,930	1,842
Recoveries from tenants and other income	30,316	28,263	61,357	54,190
Management, transaction, and other fees	6,253	6,741	12,572	13,502
Total revenues	134,892	122,307	268,173	242,685
Operating expenses:
Depreciation and amortization	36,023	31,082	73,929	62,199
Operating and maintenance	19,498	17,481	40,003	34,622
General and administrative	15,223	14,966	29,421	32,942
Real estate taxes	14,898	13,750	29,697	26,980
Other operating expenses	1,795	1,579	3,968	3,098
Total operating expenses	87,437	78,858	177,018	159,841
Other expense (income):
Interest expense, net of interest income of $465 and $292, and $681 and $751 for the three and six months ended June 30, 2014 and 2013, respectively	27,445	27,781	54,580	55,613
Provision for impairment	0	0	225	0
Net investment (income) loss from deferred compensation plan, including unrealized (gains) loss of ($290) and $17, and ($183) and $848 for the three and six months ended June 30, 2014 and 2013, respectively	(628)	38	(821)	(1,034)
Total other expense	26,817	27,819	53,984	54,579
Income before equity in income of investments in real estate partnerships	20,638	15,630	37,171	28,265
Equity in income of investments in real estate partnerships	8,832	6,012	16,640	11,888
Income from continuing operations	29,470	21,642	53,811	40,153
Discontinued operations, net:
Operating income	0	2,700	0	5,323
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	11,410	0	11,410
Income from discontinued operations	0	14,110	0	16,733
Income before gain on sale of real estate	29,470	35,752	53,811	56,886
Gain on sale of real estate	(1,691)	(1,717)	(2,406)	(1,717)
Net income	31,161	37,469	56,217	58,603
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(360)	(270)	(719)	(545)
Income attributable to noncontrolling interests	(360)	(270)	(719)	(545)
Net income attributable to the Company	30,801	37,199	55,498	58,058
Preferred unit distributions	(5,266)	(5,265)	(10,531)	(10,531)
Net income attributable to common unit holders	$ 25,535	$ 31,934	$ 44,967	$ 47,527
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.28	$ 0.19	$ 0.48	$ 0.34
Discontinued operations (in dollars per share)	$ 0.00	$ 0.16	$ 0.00	$ 0.18
Net income attributable to common unit holders (in dollars per share)	$ 0.28	$ 0.35	$ 0.48	$ 0.52
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.28	$ 0.19	$ 0.48	$ 0.34
Discontinued operations (in dollars per share)	$ 0.00	$ 0.16	$ 0.00	$ 0.18
Net income attributable to common unit holders (in dollars per share)	$ 0.28	$ 0.35	$ 0.48	$ 0.52