Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other expense (income):
Income tax benefit of taxable REIT subsidiary	$ 0	$ (840)	$ 0	$ (608)
Discontinued operations, net:
Gain on sale of operating properties, net	11,410	2,304	11,410	8,605
Parent Company [Member]
Revenues:
Minimum rent	89,611	90,164	178,333	179,533
Percentage rent	298	398	1,846	1,558
Recoveries from tenants and other income	29,192	29,734	55,877	55,918
Management, transaction, and other fees	6,741	6,469	13,502	13,618
Total revenues	125,842	126,765	249,558	250,627
Operating expenses:
Depreciation and amortization	31,930	31,737	63,871	63,108
Operating and maintenance	17,982	17,421	35,563	35,572
General and administrative	14,966	14,020	32,942	30,142
Real estate taxes	14,204	13,799	27,883	28,740
Other expenses	1,580	1,111	3,083	2,447
Total operating expenses	80,662	78,088	163,342	160,009
Other expense (income):
Interest expense, net of interest income of $292 and $377, and $751 and $913 for the three and six months ended June 30, 2013 and 2012, respectively	27,781	28,377	55,613	57,335
Provision for impairment	0	19,008	0	19,008
Net investment loss (income) from deferred compensation plan, including unrealized gains (loss) of $17 and ($499), and $848 and $725 for the three and six months ended June 30, 2013 and 2012, respectively	38	444	(1,034)	(1,084)
Total other expense	27,819	47,829	54,579	75,259
Income before equity in income of investments in real estate partnerships	17,361	848	31,637	15,359
Equity in income of investments in real estate partnerships	6,012	10,804	11,888	13,770
Income from continuing operations before tax	23,373	11,652	43,525	29,129
Income tax benefit of taxable REIT subsidiary	0	(840)	0	(608)
Income from continuing operations	23,373	12,492	43,525	29,737
Discontinued operations, net:
Operating income (loss)	969	(3,427)	1,951	(2,073)
Gain on sale of operating properties, net	11,410	2,304	11,410	8,605
Income (loss) from discontinued operations	12,379	(1,123)	13,361	6,532
Income before gain (loss) on sale of real estate	35,752	11,369	56,886	36,269
Gain (loss) on sale of real estate	(1,717)	21	(1,717)	(1,814)
Net income	37,469	11,348	58,603	38,083
Net Income (Loss) Attributable to Noncontrolling Interest, Preferred Unit Holders (Deprecated 2013-01-31)	0	0	0	629
Noncontrolling interests:
Exchangeable operating partnership units	(70)	(23)	(109)	(77)
Limited partners’ interests in consolidated partnerships	(270)	(232)	(545)	(424)
(Income) loss attributable to noncontrolling interests	(340)	(255)	(654)	128
Net income attributable to the Company	37,129	11,093	57,949	38,211
Preferred stock dividends	(5,265)	(5,396)	(10,531)	(19,333)
Net Income (Loss) attributable to Common Stockholders	31,864	5,697	47,418	18,878
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.21	$ 0.07	$ 0.37	$ 0.14
Discontinued operations (in dollars per share)	$ 0.14	$ (0.01)	$ 0.15	$ 0.07
Net income attributable to common stockholders (in dollars per share)	$ 0.35	$ 0.06	$ 0.52	$ 0.21
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.21	$ 0.07	$ 0.37	$ 0.14
Discontinued operations (in dollars per share)	$ 0.14	$ (0.01)	$ 0.15	$ 0.07
Net income attributable to common stockholders (in dollars per share)	$ 0.35	$ 0.06	$ 0.52	$ 0.21
Partnership Interest [Member]
Revenues:
Minimum rent	89,611	90,164	178,333	179,533
Percentage rent	298	398	1,846	1,558
Recoveries from tenants and other income	29,192	29,734	55,877	55,918
Management, transaction, and other fees	6,741	6,469	13,502	13,618
Total revenues	125,842	126,765	249,558	250,627
Operating expenses:
Depreciation and amortization	31,930	31,737	63,871	63,108
Operating and maintenance	17,982	17,421	35,563	35,572
General and administrative	14,966	14,020	32,942	30,142
Real estate taxes	14,204	13,799	27,883	28,740
Other expenses	1,580	1,111	3,083	2,447
Total operating expenses	80,662	78,088	163,342	160,009
Other expense (income):
Interest expense, net of interest income of $292 and $377, and $751 and $913 for the three and six months ended June 30, 2013 and 2012, respectively	27,781	28,377	55,613	57,335
Provision for impairment	0	19,008	0	19,008
Net investment loss (income) from deferred compensation plan, including unrealized gains (loss) of $17 and ($499), and $848 and $725 for the three and six months ended June 30, 2013 and 2012, respectively	38	444	(1,034)	(1,084)
Total other expense	27,819	47,829	54,579	75,259
Income before equity in income of investments in real estate partnerships	17,361	848	31,637	15,359
Equity in income of investments in real estate partnerships	6,012	10,804	11,888	13,770
Income from continuing operations before tax	23,373	11,652	43,525	29,129
Income tax benefit of taxable REIT subsidiary	0	(840)	0	(608)
Income from continuing operations	23,373	12,492	43,525	29,737
Discontinued operations, net:
Operating income (loss)	969	(3,427)	1,951	(2,073)
Gain on sale of operating properties, net	11,410	2,304	11,410	8,605
Income (loss) from discontinued operations	12,379	(1,123)	13,361	6,532
Income before gain (loss) on sale of real estate	35,752	11,369	56,886	36,269
Gain (loss) on sale of real estate	(1,717)	21	(1,717)	(1,814)
Net income	37,469	11,348	58,603	38,083
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	(270)	(232)	(545)	(424)
(Income) loss attributable to noncontrolling interests	(270)	(232)	(545)	(424)
Net income attributable to the Company	37,199	11,116	58,058	37,659
Preferred unit distributions	(5,265)	(5,396)	(10,531)	(18,704)
Net income attributable to common unit holders	$ 31,934	$ 5,720	$ 47,527	$ 18,955
Income per common share/unit - basic:
Continuing operations (in dollars per share)	$ 0.21	$ 0.07	$ 0.37	$ 0.14
Discontinued operations (in dollars per share)	$ 0.14	$ (0.01)	$ 0.15	$ 0.07
Net income attributable to common unit holders (in dollars per share)	$ 0.35	$ 0.06	$ 0.52	$ 0.21
Income per common share/unit - diluted:
Continuing operations (in dollars per share)	$ 0.21	$ 0.07	$ 0.37	$ 0.14
Discontinued operations (in dollars per share)	$ 0.14	$ (0.01)	$ 0.15	$ 0.07
Net income attributable to common unit holders (in dollars per share)	$ 0.35	$ 0.06	$ 0.52	$ 0.21