Reportable Segments (Tables)

3 Months Ended

Mar. 31, 2012

Reportable Segments (Tables) [Abstracts]

Reportable Segments Schedule

	Quarter Ended March 31, 2012
	Northeast		Northwest		Southeast		Southwest		Other (3)		Total
Rental income:
Same store (1)	$	174,263	$	95,751	$	91,757	$	112,186	$	—	$	473,957
Non-same store/other (2) (3)	20,378		10,166		4,770		13,930		2,394		51,638
Total rental income	194,641		105,917		96,527		126,116		2,394		525,595
Operating expenses:
Same store (1)	66,000		33,303		36,170		37,581		—		173,054
Non-same store/other (2) (3)	4,583		5,469		1,664		4,662		2,343		18,721
Total operating expenses	70,583		38,772		37,834		42,243		2,343		191,775
NOI:
Same store (1)	108,263		62,448		55,587		74,605		—		300,903
Non-same store/other (2) (3)	15,795		4,697		3,106		9,268		51		32,917
Total NOI	$	124,058	$	67,145	$	58,693	$	83,873	$	51	$	333,820
Total assets	$	6,458,496	$	2,931,942	$	2,483,091	$	3,392,065	$	1,215,653	$	16,481,247
Capital expenditures	$	9,843	$	6,506	$	7,440	$	5,419	$	1,017	$	30,225

(1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2011, less properties subsequently sold, which represented 105,612 apartment units.

(2) Non-same store primarily includes properties acquired after January 1, 2011, plus any properties in lease-up and not stabilized as of January 1, 2011.

(3) Other includes development and other corporate operations.

	Quarter Ended March 31, 2011
	Northeast		Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	164,859	$	88,197	$	88,061	$	108,115	$	—		$	449,232
Non-same store/other (2) (3)	7,658		899		2,924		3,715		122			15,318
Total rental income	172,517		89,096		90,985		111,830		122			464,550
Operating expenses:
Same store (1)	65,195		32,279		35,496		37,047		—			170,017
Non-same store/other (2) (3)	2,486		268		1,134		1,927		3,735			9,550
Total operating expenses	67,681		32,547		36,630		38,974		3,735			179,567
NOI:
Same store (1)	99,664		55,918		52,565		71,068		—			279,215
Non-same store/other (2) (3)	5,172		631		1,790		1,788		(3,613		)	5,768
Total NOI	$	104,836	$	56,549	$	54,355	$	72,856	$	(3,613	)	$	284,983

(1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2011, less properties subsequently sold, which represented 105,612 apartment units.

(2) Non-same store primarily includes properties acquired after January 1, 2011, plus any properties in lease-up and not stabilized as of January 1, 2011.

Reconciliation of NOI

	Quarter Ended March 31,
	2012			2011
Rental income	$	525,595		$	464,550
Property and maintenance expense	(112,379		)	(105,047		)
Real estate taxes and insurance expense	(55,987		)	(52,139		)
Property management expense	(23,409		)	(22,381		)
Total operating expenses	(191,775		)	(179,567		)
Net operating income	$	333,820		$	284,983