Segment Information (Tables)

3 Months Ended

Mar. 31, 2012

Mar. 31, 2011

Segment Reporting, Measurement Disclosures [Abstract]

Company's Reportable Segments [Table Text Block]

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

N

Schedule of Segment Reporting Information, by Segment, Revenue and Net Operating Income [Table Text Block]

		For the Three Months Ended
		March 31,
		2012			2011
Operating revenue
	Northeast - Southeastern PA	$	42,195		$	45,265
	Northeast - Lehigh / Central PA	24,077			28,200
	Northeast - Other	17,400			18,293
	Central	32,144			31,692
	South	54,012			56,364
	Metro	8,188			7,149
	United Kingdom	1,162			1,132
Segment-level operating revenue		179,178			188,095
Reconciliation to total operating revenues
	Discontinued operations	(9,409		)	(21,961		)
	Other	168			—
Total operating revenue		$	169,937		$	166,134
Net operating income
	Northeast - Southeastern PA	$	25,170		$	25,524
	Northeast - Lehigh / Central PA	16,195			17,449
	Northeast - Other	9,105			9,194
	Central	17,747			17,472
	South	32,654			34,002
	Metro	5,629			5,957
	United Kingdom	(229		)	(49		)
Segment-level net operating income		106,271			109,549
Reconciliation to income from continuing operations
	Interest expense (1)	(30,904		)	(36,169		)
	Depreciation/amortization expense (2)	(25,652		)	(28,406		)
	Gain on property dispositions	523			1,161
	Equity in earnings of unconsolidated joint ventures	916			534
	General and administrative expense (2)	(11,550		)	(10,449		)
	Discontinued operations excluding gain on property dispositions	(2,847		)	(3,759		)
	Income taxes	(178		)	(550		)
	Other	(888		)	(1,197		)
Income from continuing operations		$	35,691		$	30,714