Segment Information (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2011

Dec. 31, 2010

Segment Reporting Information [Line Items]

Company's Reportable Segments

REGIONS	MARKETS
Northeast	Southeastern PA; Lehigh/Central PA; New Jersey; Maryland
Central	Minnesota; Chicago/Milwaukee; Houston; Arizona
South	Richmond; Virginia Beach; Carolinas; Jacksonville; Orlando; South Florida; Tampa
Metro	Philadelphia; Metro Washington, D.C.
United Kingdom	County of Kent; West Midlands

REGIONS (BEFORE 2011 CHANGES)	MARKETS (BEFORE 2011 CHANGES)
Northeast	Southeastern PA; Lehigh/Central PA; New Jersey
Midwest	Minnesota; Milwaukee; Chicago
Mid-Atlantic	Maryland; Carolinas; Richmond; Virginia Beach
South	Jacksonville; Orlando; South Florida; Tampa; Texas; Arizona
Philadelphia/D.C.	Philadelphia; Metro Washington, D.C.
United Kingdom	County of Kent; West Midlands

Performance of the Reportable Segments Based on Property Level Operating Income

FOR THE THREE MONTHS ENDED SEPTEMBER 30, 2011

	NORTHEAST
	SOUTHEASTERN PA		LEHIGH/ CENTRAL  PA		NORTHEAST - OTHER		CENTRAL		SOUTH		METRO		UNITED KINGDOM		TOTAL
Operating revenue	$	42,673	$	22,523	$	17,312	$	31,055	$	53,469	$	7,039	$	1,108	$	175,179
Rental property expenses and real estate taxes	14,232		5,132		6,673		11,179		17,562		1,718		106		56,602
Property level operating income	$	28,441	$	17,391	$	10,639	$	19,876	$	35,907	$	5,321	$	1,002	118,577
Interest and other income															2,019
Interest expense															(31,188		)
General and administrative															(13,625		)
Depreciation and amortization															(41,414		)
Income before property dispositions, income taxes, equity in earnings of unconsolidated joint ventures and discontinued operations															34,369
Gain on property dispositions															1,898
Income taxes															(356		)
Equity in earnings of unconsolidated joint ventures															827
Discontinued operations															4,943
Net income															$	41,681

FOR THE THREE MONTHS ENDED SEPTEMBER 30, 2010

	NORTHEAST
	SOUTHEASTERN PA		LEHIGH/ CENTRAL PA		NORTHEAST - OTHER		CENTRAL		SOUTH		METRO		UNITED KINGDOM		TOTAL
Operating revenue	$	45,475	$	21,388	$	18,335	$	28,856	$	53,107	$	7,214	$	1,081	$	175,456
Rental property expenses and real estate taxes	14,528		4,752		6,889		10,001		18,010		1,680		236		56,096
Property level operating income	$	30,947	$	16,636	$	11,446	$	18,855	$	35,097	$	5,534	$	845	119,360
Interest and other income															2,400
Interest expense															(32,410		)
General and administrative															(12,608		)
Depreciation and amortization															(39,996		)
Income before property dispositions, income taxes, equity in earnings of unconsolidated joint ventures and discontinued operations															36,746
Gain on property dispositions															691
Income taxes															(475		)
Equity in earnings of unconsolidated joint ventures															385
Discontinued operations															3,659
Net income															$	41,006

FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2011

	NORTHEAST
	SOUTHEASTERN PA		LEHIGH/ CENTRAL PA		NORTHEAST - OTHER		CENTRAL		SOUTH		METRO		UNITED KINGDOM		TOTAL
Operating revenue	$	130,766	$	67,829	$	52,630	$	89,186	$	159,088	$	21,146	$	3,321	$	523,966
Rental property expenses and real estate taxes	44,400		15,489		19,520		31,293		49,140		4,105		594		164,541
Property level operating income	$	86,366	$	52,340	$	33,110	$	57,893	$	109,948	$	17,041	$	2,727	359,425
Interest and other income															7,011
Interest expense															(96,354		)
General and administrative															(42,848		)
Depreciation and amortization															(123,840		)
Income before property dispositions, income taxes, equity in earnings of unconsolidated joint ventures and discontinued operations															103,394
Gain on property dispositions															3,361
Income taxes															(969		)
Equity in earnings of unconsolidated joint ventures															2,470
Discontinued operations															61,209
Net income															$	169,465

FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2010

	NORTHEAST
	SOUTHEASTERN PA		LEHIGH/ CENTRAL PA		NORTHEAST - OTHER		CENTRAL		SOUTH		METRO		UNITED KINGDOM		TOTAL
Operating revenue	$	135,523	$	61,510	$	55,295	$	86,047	$	158,316	$	21,442	$	3,126	$	521,259
Rental property expenses and real estate taxes	44,056		14,100		20,307		30,236		51,936		4,584		687		165,906
Property level operating income	$	91,467	$	47,410	$	34,988	$	55,811	$	106,380	$	16,858	$	2,439	355,353
Interest and other income															7,748
Interest expense															(103,922		)
General and administrative															(40,023		)
Depreciation and amortization															(119,091		)
Income before property dispositions, income taxes, equity in earnings of unconsolidated joint ventures and discontinued operations															100,065
Gain on property dispositions															3,701
Income taxes															(1,430		)
Equity in earnings of unconsolidated joint ventures															1,562
Discontinued operations															12,944
Net income															$	116,842