Consolidated Statements of Operations (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Parent Company [Member]
Revenues
Minimum rent	$ 90,129	$ 86,486	$ 268,169	$ 257,389
Percentage rent	430	400	1,488	1,023
Recoveries from tenants and other income	28,248	27,383	83,040	83,150
Management, transaction, and other fees	6,940	6,524	26,993	22,974
Total revenues	125,747	120,793	379,690	364,536
Operating Expenses
Depreciation and amortization	33,166	30,181	100,006	92,324
Operating and maintenance	18,101	17,147	55,106	51,521
General and administrative	11,671	17,761	43,801	45,734
Real estate taxes	13,533	13,788	42,163	42,267
Provision for doubtful accounts	326	248	2,534	2,634
Other expenses (income)	1,901	2,380	1,737	4,071
Total operating expenses	78,698	81,505	245,347	238,551
Other expense (income):
Interest expense, net of interest income	30,867	32,209	92,297	91,972
Loss (gain) on sale of properties in development	0	(479)	0	(1,044)
Provision for Impairment	6,362	0	6,362	0
(Income) loss from deferred compensation plan	2,283	(1,398)	1,395	(1,026)
Loss on derivatve instruments	0	2,341	0	1,419
Total other expense (income)	(39,512)	(27,991)	(100,054)	(88,483)
Income before equity in income (loss) of investments in real estate partnerships	7,537	11,297	34,289	37,502
Equity in income (loss) of investments in real estate partnerships	4,825	2,102	4,788	(8)
Income from continuing operations	12,362	13,399	39,077	37,494
Discontinued operations, net:
Operating (loss) income	(142)	470	210	756
(Loss) gain on sale of operating properties and properties in development	2,321	4	2,321	6,767
(Loss) income from discontinued operations	2,179	474	2,531	7,523
Net income	14,541	13,873	41,608	45,017
Noncontrolling interests:
Preferred units	(931)	(931)	(2,794)	(2,794)
Exchangeable operating partnership units	(27)	(34)	(77)	(155)
Limited partners' interest in consolidated partnerships	(154)	(95)	(425)	(271)
Net income attributable to noncontrolling interests	(1,112)	(1,060)	(3,296)	(3,220)
Net income attributable to controlling interests	13,429	12,813	38,312	41,797
Preferred stock dividends	(4,919)	(4,919)	(14,756)	(14,756)
Net income attributable to common stockholders	8,510	7,894	23,556	27,041
Income per common share/unit - basic:
Continuing operations	$ 0.07	$ 0.09	$ 0.23	$ 0.24
Discontinued operations	$ 0.02	$ 0.01	$ 0.03	$ 0.09
Net income attributable to common stockholders	$ 0.09	$ 0.10	$ 0.26	$ 0.33
Income per common share/unit - diluted:
Continuing operations	$ 0.07	$ 0.09	$ 0.23	$ 0.23
Discontinued operations	$ 0.02	$ 0.00	$ 0.03	$ 0.09
Net income attributable to common stockholders	$ 0.09	$ 0.09	$ 0.26	$ 0.32
Partnership Interest [Member]
Revenues
Minimum rent	90,129	86,486	268,169	257,389
Percentage rent	430	400	1,488	1,023
Recoveries from tenants and other income	28,248	27,383	83,040	83,150
Management, transaction, and other fees	6,940	6,524	26,993	22,974
Total revenues	125,747	120,793	379,690	364,536
Operating Expenses
Depreciation and amortization	33,166	30,181	100,006	92,324
Operating and maintenance	18,101	17,147	55,106	51,521
General and administrative	11,671	17,761	43,801	45,734
Real estate taxes	13,533	13,788	42,163	42,267
Provision for doubtful accounts	326	248	2,534	2,634
Other expenses (income)	1,901	2,380	1,737	4,071
Total operating expenses	78,698	81,505	245,347	238,551
Other expense (income):
Interest expense, net of interest income	30,867	32,209	92,297	91,972
Loss (gain) on sale of properties in development	0	(479)	0	(1,044)
Provision for Impairment	6,362	0	6,362	0
(Income) loss from deferred compensation plan	2,283	(1,398)	1,395	(1,026)
Loss on derivatve instruments	0	2,341	0	1,419
Total other expense (income)	(39,512)	(27,991)	(100,054)	(88,483)
Income before equity in income (loss) of investments in real estate partnerships	7,537	11,297	34,289	37,502
Equity in income (loss) of investments in real estate partnerships	4,825	2,102	4,788	(8)
Income from continuing operations	12,362	13,399	39,077	37,494
Discontinued operations, net:
Operating (loss) income	(142)	470	210	756
(Loss) gain on sale of operating properties and properties in development	2,321	4	2,321	6,767
(Loss) income from discontinued operations	2,179	474	2,531	7,523
Net income	14,541	13,873	41,608	45,017
Noncontrolling interests:
Limited partners' interest in consolidated partnerships	(154)	(95)	(425)	(271)
Net income attributable to noncontrolling interests	(154)	(95)	(425)	(271)
Net income attributable to controlling interests	14,387	13,778	41,183	44,746
Preferred unit distributions	(5,850)	(5,850)	(17,550)	(17,550)
Net income attributable to common unit holders	$ 8,537	$ 7,928	$ 23,633	$ 27,196
Income per common share/unit - basic:
Continuing operations	$ 0.07	$ 0.09	$ 0.23	$ 0.24
Discontinued operations	$ 0.02	$ 0.01	$ 0.03	$ 0.09
Net income attributable to common unit holders	$ 0.09	$ 0.10	$ 0.26	$ 0.33
Income per common share/unit - diluted:
Continuing operations	$ 0.07	$ 0.09	$ 0.23	$ 0.23
Discontinued operations	$ 0.02	$ 0.00	$ 0.03	$ 0.09
Net income attributable to common unit holders	$ 0.09	$ 0.09	$ 0.26	$ 0.32