Reportable Segments (Tables)

12 Months Ended

Dec. 31, 2010

Reportable Segments (Tables) [Abstracts]

Reportable Segments Schedule

	Year Ended December 31, 2010
	Northeast		Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	574,147	$	353,123	$	383,475	$	417,523	$	—		$	1,728,268
Non-same store/other (2) (3)		112,747		18,042		9,271		33,456		84,259			257,775
Properties sold — March YTD 2011 (4)		—		—		—		—		(28,670	)		(28,670	)
Total rental income		686,894		371,165		392,746		450,979		55,589			1,957,373
Operating expenses:
Same store (1)		215,365		132,331		157,518		149,449		—			654,663
Non-same store/other (2) (3)		54,780		7,950		4,126		15,136		69,823			151,815
Properties sold — March YTD 2011 (4)		—		—		—		—		(11,248	)		(11,248	)
Total operating expenses		270,145		140,281		161,644		164,585		58,575			795,230
NOI:
Same store (1)		358,782		220,792		225,957		268,074		—			1,073,605
Non-same store/other (2) (3)		57,967		10,092		5,145		18,320		14,436			105,960
Properties sold — March YTD 2011 (4)		—		—		—		—		(17,422	)		(17,422	)
Total NOI	$	416,749	$	230,884	$	231,102	$	286,394	$	(2,986	)	$	1,162,143
Total assets	$	6,211,534	$	2,665,707	$	2,602,318	$	3,240,170	$	1,464,465		$	16,184,194

(1)	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2009, less properties subsequently sold, which represented 112,042 apartment units.
(2)	Non-same store primarily includes properties acquired after January 1, 2009, plus any properties in lease-up and not stabilized as of January 1, 2009.
(3)	Other includes ECH, development, condominium conversion overhead of $0.6 million and other corporate operations. Also reflects a $10.5 million elimination of rental income recorded in Northeast, Northwest, Southeast and Southwest operating segments related to ECH.
(4)	Properties sold — March YTD 2011 reflects discontinued operations for properties sold during the first three months of 2011.

	Year Ended December 31, 2009
	Northeast		Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	566,518	$	357,502	$	383,239	$	423,076	$	—		$	1,730,335
Non-same store/other (2) (3)		23,195		2,010		4,268		16,985		69,364			115,822
Properties sold — March YTD 2011 (4)		—		—		—		—		(28,304	)		(28,304	)
Total rental income		589,713		359,512		387,507		440,061		41,060			1,817,853
Operating expenses:
Same store (1)		211,352		129,696		158,977		148,483		—			648,508
Non-same store/other (2) (3)		12,798		1,851		1,727		9,418		68,692			94,486
Properties sold — March YTD 2011 (4)		—		—		—		—		(11,334	)		(11,334	)
Total operating expenses		224,150		131,547		160,704		157,901		57,358			731,660
NOI:
Same store (1)		355,166		227,806		224,262		274,593		—			1,081,827
Non-same store/other (2) (3)		10,397		159		2,541		7,567		672			21,336
Properties sold — March YTD 2011 (4)		—		—		—		—		(16,970	)		(16,970	)
Total NOI	$	365,563	$	227,965	$	226,803	$	282,160	$	(16,298	)	$	1,086,193
Total assets	$	5,435,072	$	2,474,775	$	2,674,499	$	2,971,396	$	1,861,773		$	15,417,515

(1)	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2009, less properties subsequently sold, which represented 112,042 apartment units.
(2)	Non-same store primarily includes properties acquired after January 1, 2009, plus any properties in lease-up and not stabilized as of January 1, 2009.
(3)	Other includes ECH, development, condominium conversion overhead of $1.4 million and other corporate operations. Also reflects a $9.6 million elimination of rental income recorded in Northeast, Northwest, Southeast and Southwest operating segments related to ECH.

(4) Properties sold — March YTD 2011 reflects discontinued operations for properties sold during the first three months of 2011.

	Year Ended December 31, 2008
	Northeast		Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	553,712	$	372,197	$	407,871	$	444,403	$	—		$	1,778,183
Non-same store/other (2) (3)		37,000		18,347		6,090		23,400		101,934			186,771
Properties sold in 2010 (4)		—		—		—		—		(88,681	)		(88,681	)
Properties sold — March YTD 2011 (5)		—		—		—		—		(28,870	)		(28,870	)
Total rental income		590,712		390,544		413,961		467,803		(15,617	)		1,847,403
Operating expenses:
Same store (1)		199,673		128,448		166,022		150,980		—			645,123
Non-same store/other (2) (3)		16,806		7,664		2,995		14,363		101,742			143,570
Properties sold in 2010 (4)		—		—		—		—		(31,205	)		(31,205	)
Properties sold — March YTD 2011 (5)		—		—		—		—		(11,069	)		(11,069	)
Total operating expenses		216,479		136,112		169,017		165,343		59,468			746,419
NOI:
Same store (1)		354,039		243,749		241,849		293,423		—			1,133,060
Non-same store/other (2) (3)		20,194		10,683		3,095		9,037		192			43,201
Properties sold in 2010 (4)		—		—		—		—		(57,476	)		(57,476	)
Properties sold — March YTD 2011 (5)		—		—		—		—		(17,801	)		(17,801	)
Total NOI	$	374,233	$	254,432	$	244,944	$	302,460	$	(75,085	)	$	1,100,984

(1)	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2008, less properties subsequently sold, which represented 113,598 apartment units.
(2)	Non-same store primarily includes properties acquired after January 1, 2008, plus any properties in lease-up and not stabilized as of January 1, 2008.
(3)	Other includes ECH, development, condominium conversion overhead of $2.8 million and other corporate operations. Also reflects a $13.6 million elimination of rental income recorded in Northeast, Northwest, Southeast and Southwest operating segments related to ECH.
(4)	Reflects discontinued operations for properties sold during 2010.
(5)	Properties sold — March YTD 2011 reflects discontinued operations for properties sold during the first three months of 2011.

Reconciliation of NOI

	Year Ended December 31,
	2010			2009			2008
Rental income	$	1,957,373		$	1,817,853		$	1,847,403
Property and maintenance expense		(490,301	)		(456,628	)		(477,814	)
Real estate taxes and insurance expense		(224,842	)		(203,732	)		(191,781	)
Property management expense		(80,087	)		(71,300	)		(76,824	)
Total operating expenses		(795,230	)		(731,660	)		(746,419	)
Net operating income	$	1,162,143		$	1,086,193		$	1,100,984