Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2011

Schedule of Quarterly Financial Information [Table Text Block]

	First Quarter			Second Quarter		Third Quarter		Fourth Quarter
2011	3/31			6/30		9/30		12/31
Total revenues (1)	$	466,356		$	484,290	$	504,496	$	514,127
Operating income (1)	115,953			141,104		147,850		159,953
(Loss) income from continuing operations (1)	(8,913		)	16,298		32,287		36,771
Discontinued operations, net (1)	141,979			565,455		80,690		70,630
Net income *	133,066			581,753		112,977		107,401
Net income available to Common Shares	123,865			552,457		104,382		99,016
Earnings per share – basic:
Net income available to Common Shares	$	0.42		$	1.88	$	0.35	$	0.33
Weighted average Common Shares outstanding	292,895			294,663		295,831		295,990
Earnings per share – diluted:
Net income available to Common Shares	$	0.42		$	1.85	$	0.35	$	0.33
Weighted average Common Shares outstanding	292,895			312,199		312,844		312,731

(1) The amounts presented for 2011 are not equal to the same amounts previously reported in the Form 10-K filed with the SEC on February 24, 2012 as a result of changes in discontinued operations due to additional property sales which occurred throughout the first three months of 2012. Below is a reconciliation to the amounts previously reported in the Form 10-K:

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2011	3/31			6/30			9/30			12/31
Total revenues previously reported in 2011 Form 10-K	$	471,230		$	489,353		$	509,623		$	519,257
Total revenues subsequently reclassified to discontinued operations	(4,874		)	(5,063		)	(5,127		)	(5,130		)
Total revenues disclosed in Form 8-K	$	466,356		$	484,290		$	504,496		$	514,127
Operating income previously reported in 2011 Form 10-K	$	117,910		$	143,295		$	149,979		$	162,148
Operating income subsequently reclassified to discontinued operations	(1,957		)	(2,191		)	(2,129		)	(2,195		)
Operating income disclosed in Form 8-K	$	115,953		$	141,104		$	147,850		$	159,953
(Loss) income from continuing operations previously reported in 2011    Form 10-K	$	(7,569	)	$	18,185		$	34,416		$	38,966
Income from continuing operations subsequently reclassified to    discontinued operations	(1,344		)	(1,887		)	(2,129		)	(2,195		)
(Loss) income from continuing operations disclosed in Form 8-K	$	(8,913	)	$	16,298		$	32,287		$	36,771
Discontinued operations, net previously reported in 2011 Form 10-K	$	140,635		$	563,568		$	78,561		$	68,435
Discontinued operations, net from properties sold subsequent to the    respective reporting period	1,344			1,887			2,129			2,195
Discontinued operations, net disclosed in Form 8-K	$	141,979		$	565,455		$	80,690		$	70,630

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2010	3/31			6/30			9/30			12/31
Total revenues (2)	$	416,844		$	434,499		$	446,934		$	455,967
Operating income (2)	95,837			95,644			102,631			74,578
(Loss) from continuing operations (2)	(22,381		)	(13,921		)	(2,276		)	(49,721		)
Discontinued operations, net (2)	80,237			24,010			32,102			247,933
Net income *	57,856			10,089			29,826			198,212
Net income available to Common Shares	51,863			6,343			25,166			185,870
Earnings per share – basic:
Net income available to Common Shares	$	0.18		$	0.02		$	0.09		$	0.65
Weighted average Common Shares outstanding	280,645			282,217			282,717			285,916
Earnings per share – diluted:
Net income available to Common Shares	$	0.18		$	0.02		$	0.09		$	0.65
Weighted average Common Shares outstanding	280,645			282,217			282,717			285,916

(2) The amounts presented for 2010 are not equal to the same amounts previously reported in the Form 10-K filed with the SEC on February 24, 2012 as a result of changes in discontinued operations due to additional property sales which occurred throughout the first three months of 2012. Below is a reconciliation to the amounts previously reported in the Form 10-K:

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2010	3/31			6/30			9/30			12/31
Total revenues previously reported in 2011 Form 10-K	$	421,517		$	439,258		$	451,745		$	460,748
Total revenues subsequently reclassified to discontinued operations	(4,673		)	(4,759		)	(4,811		)	(4,781		)
Total revenues disclosed in Form 8-K	$	416,844		$	434,499		$	446,934		$	455,967
Operating income previously reported in 2011 Form 10-K	$	97,540		$	97,590		$	104,444		$	76,503
Operating income subsequently reclassified to discontinued    operations	(1,703		)	(1,946		)	(1,813		)	(1,925		)
Operating income disclosed in Form 8-K	$	95,837		$	95,644		$	102,631		$	74,578
(Loss) from continuing operations previously reported in 2011 Form    10-K	$	(21,315	)	$	(12,607	)	$	(1,088	)	$	(48,416	)
Income from continuing operations subsequently reclassified to     discontinued operations	(1,066		)	(1,314		)	(1,188		)	(1,305		)
(Loss) from continuing operations disclosed in Form 8-K	$	(22,381	)	$	(13,921	)	$	(2,276	)	$	(49,721	)
Discontinued operations, net previously reported in 2011 Form 10-K	$	79,171		$	22,696		$	30,914		$	246,628
Discontinued operations, net from properties sold subsequent to the     respective reporting period	1,066			1,314			1,188			1,305
Discontinued operations, net disclosed in Form 8-K	$	80,237		$	24,010		$	32,102		$	247,933

* The Company did not have any extraordinary items or cumulative effect of change in accounting principle during the years ended December 31, 2011 and 2010. Therefore, income before extraordinary items and cumulative effect of change in accounting principle is not shown as it was equal to the net income amounts disclosed above.

Operating Partnership [Member]

Schedule of Quarterly Financial Information [Table Text Block]

	First Quarter			Second Quarter		Third Quarter		Fourth Quarter
2011	3/31			6/30		9/30		12/31
Total revenues (1)	$	466,356		$	484,290	$	504,496	$	514,127
Operating income (1)	115,953			141,104		147,850		159,953
(Loss) income from continuing operations (1)	(8,913		)	16,298		32,287		36,771
Discontinued operations, net (1)	141,979			565,455		80,690		70,630
Net income *	133,066			581,753		112,977		107,401
Net income available to Units	129,640			578,215		109,124		103,521
Earnings per Unit – basic:
Net income available to Units	$	0.42		$	1.88	$	0.35	$	0.33
Weighted average Units outstanding	306,248			307,954		308,884		309,120
Earnings per Unit – diluted:
Net income available to Units	$	0.42		$	1.85	$	0.35	$	0.33
Weighted average Units outstanding	306,248			312,199		312,844		312,731

(1) The amounts presented for 2011 are not equal to the same amounts previously reported in the Form 10-K filed with the SEC on February 24, 2012 as a result of changes in discontinued operations due to additional property sales which occurred throughout the first three months of 2012. Below is a reconciliation to the amounts previously reported in the Form 10-K:

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2011	3/31			6/30			9/30			12/31
Total revenues previously reported in 2011 Form 10-K	$	471,230		$	489,353		$	509,623		$	519,257
Total revenues subsequently reclassified to discontinued operations	(4,874		)	(5,063		)	(5,127		)	(5,130		)
Total revenues disclosed in Form 8-K	$	466,356		$	484,290		$	504,496		$	514,127
Operating income previously reported in 2011 Form 10-K	$	117,910		$	143,295		$	149,979		$	162,148
Operating income subsequently reclassified to discontinued operations	(1,957		)	(2,191		)	(2,129		)	(2,195		)
Operating income disclosed in Form 8-K	$	115,953		$	141,104		$	147,850		$	159,953
(Loss) income from continuing operations previously reported in 2011    Form 10-K	$	(7,569	)	$	18,185		$	34,416		$	38,966
Income from continuing operations subsequently reclassified to    discontinued operations	(1,344		)	(1,887		)	(2,129		)	(2,195		)
(Loss) income from continuing operations disclosed in Form 8-K	$	(8,913	)	$	16,298		$	32,287		$	36,771
Discontinued operations, net previously reported in 2011 Form 10-K	$	140,635		$	563,568		$	78,561		$	68,435
Discontinued operations, net from properties sold subsequent to the    respective reporting period	1,344			1,887			2,129			2,195
Discontinued operations, net disclosed in Form 8-K	$	141,979		$	565,455		$	80,690		$	70,630

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2010	3/31			6/30			9/30			12/31
Total revenues (2)	$	416,844		$	434,499		$	446,934		$	455,967
Operating income (2)	95,837			95,644			102,631			74,578
(Loss) from continuing operations (2)	(22,381		)	(13,921		)	(2,276		)	(49,721		)
Discontinued operations, net (2)	80,237			24,010			32,102			247,933
Net income *	57,856			10,089			29,826			198,212
Net income available to Units	54,486			6,656			26,397			194,802
Earnings per Unit – basic:
Net income available to Units	$	0.18		$	0.02		$	0.09		$	0.65
Weighted average Units outstanding	294,450			295,898			296,348			299,363
Earnings per Unit – diluted:
Net income available to Units	$	0.18		$	0.02		$	0.09		$	0.65
Weighted average Units outstanding	294,450			295,898			296,348			299,363

(2) The amounts presented for 2010 are not equal to the same amounts previously reported in the Form 10-K filed with the SEC on February 24, 2012 as a result of changes in discontinued operations due to additional property sales which occurred throughout the first three months of 2012. Below is a reconciliation to the amounts previously reported in the Form 10-K:

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
2010	3/31			6/30			9/30			12/31
Total revenues previously reported in 2011 Form 10-K	$	421,517		$	439,258		$	451,745		$	460,748
Total revenues subsequently reclassified to discontinued operations	(4,673		)	(4,759		)	(4,811		)	(4,781		)
Total revenues disclosed in Form 8-K	$	416,844		$	434,499		$	446,934		$	455,967
Operating income previously reported in 2011 Form 10-K	$	97,540		$	97,590		$	104,444		$	76,503
Operating income subsequently reclassified to discontinued    operations	(1,703		)	(1,946		)	(1,813		)	(1,925		)
Operating income disclosed in Form 8-K	$	95,837		$	95,644		$	102,631		$	74,578
(Loss) from continuing operations previously reported in 2011 Form    10-K	$	(21,315	)	$	(12,607	)	$	(1,088	)	$	(48,416	)
Income from continuing operations subsequently reclassified to    discontinued operations	(1,066		)	(1,314		)	(1,188		)	(1,305		)
(Loss) from continuing operations disclosed in Form 8-K	$	(22,381	)	$	(13,921	)	$	(2,276	)	$	(49,721	)
Discontinued operations, net previously reported in 2011 Form 10-K	$	79,171		$	22,696		$	30,914		$	246,628
Discontinued operations, net from properties sold subsequent to the    respective reporting period	1,066			1,314			1,188			1,305
Discontinued operations, net disclosed in Form 8-K	$	80,237		$	24,010		$	32,102		$	247,933

* The Operating Partnership did not have any extraordinary items or cumulative effect of change in accounting principle during the years ended December 31, 2011 and 2010. Therefore, income before extraordinary items and cumulative effect of change in accounting principle is not shown as it was equal to the net income amounts disclosed above.