Reportable Segments (Tables)

6 Months Ended

Jun. 30, 2011

Reportable Segments [Abstract]

Reportable Segments Schedule

	Six Months Ended June 30, 2011
	Northeast		Northwest		Southeast		Southwest		Other (3)		Total
Rental income:
Same store (1)	$	290,625	$	169,611	$	185,295	$	213,357	$	—	$	858,888
Non-same store/other (2) (3)		64,704		18,504		8,058		17,247		6,695		115,208
Total rental income		355,329		188,115		193,353		230,604		6,695		974,096
Operating expenses:
Same store (1)		107,507		60,614		74,328		72,723		—		315,172
Non-same store/other (2) (3)		26,068		7,294		3,241		7,176		5,947		49,726
Total operating expenses		133,575		67,908		77,569		79,899		5,947		364,898
NOI:
Same store (1)		183,118		108,997		110,967		140,634		—		543,716
Non-same store/other (2) (3)		38,636		11,210		4,817		10,071		748		65,482
Total NOI	$	221,754	$	120,207	$	115,784	$	150,705	$	748	$	609,198
Total assets	$	6,216,580	$	2,664,432	$	2,575,526	$	3,229,298	$	1,712,286	$	16,398,122

(1)	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2010, less properties subsequently sold, which represented 104,163 apartment units.
(2)	Non-same store primarily includes properties acquired after January 1, 2010, plus any properties in lease-up and not stabilized as of January 1, 2010.
(3)	Other includes development, condominium conversion overhead of $0.2 million and other corporate operations.

	Six Months Ended June 30, 2010
	Northeast		Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	275,609	$	160,758	$	178,368	$	207,541	$	—		$	822,276
Non-same store/other (2) (3)		36,915		5,008		4,273		3,313		(694	)		48,815
Total rental income		312,524		165,766		182,641		210,854		(694	)		871,091
Operating expenses:
Same store (1)		106,286		60,215		74,069		75,470		—			316,040
Non-same store/other (2) (3)		16,326		2,261		2,102		1,675		10,649			33,013
Total operating expenses		122,612		62,476		76,171		77,145		10,649			349,053
NOI:
Same store (1)		169,323		100,543		104,299		132,071		—			506,236
Non-same store/other (2) (3)		20,589		2,747		2,171		1,638		(11,343	)		15,802
Total NOI	$	189,912	$	103,290	$	106,470	$	133,709	$	(11,343	)	$	522,038

(1)	Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2010, less properties subsequently sold, which represented 104,163 apartment units.
(2)	Non-same store primarily includes properties acquired after January 1, 2010, plus any properties in lease-up and not stabilized as of January 1, 2010.
(3)	Other includes development, condominium conversion overhead of $0.3 million and other corporate operations.

	Quarter Ended June 30, 2011
	Northeast		Northwest		Southeast		Southwest		Other (3)		Total
Rental income:
Same store (1)	$	161,318	$	87,338	$	93,372	$	108,394	$	—	$	450,422
Non-same store/other (2) (3)		20,581		8,323		4,099		8,909		3,777		45,689
Total rental income		181,899		95,661		97,471		117,303		3,777		496,111
Operating expenses:
Same store (1)		58,024		30,819		37,198		36,989		—		163,030
Non-same store/other (2) (3)		7,536		3,061		1,660		3,619		1,654		17,530
Total operating expenses		65,560		33,880		38,858		40,608		1,654		180,560
NOI:
Same store (1)		103,294		56,519		56,174		71,405		—		287,392
Non-same store/other (2) (3)		13,045		5,262		2,439		5,290		2,123		28,159
Total NOI	$	116,339	$	61,781	$	58,613	$	76,695	$	2,123	$	315,551

(1)	Same store primarily includes all properties acquired or completed and stabilized prior to April 1, 2010, less properties subsequently sold, which represented 105,730 apartment units.
(2)	Non-same store primarily includes properties acquired after April 1, 2010, plus any properties in lease-up and not stabilized as of April 1, 2010.
(3)	Other includes development, condominium conversion overhead of $0.1 million and other corporate operations.

	Quarter Ended June 30, 2010
	Northeast		Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	152,989	$	82,166	$	89,389	$	104,968	$	—		$	429,512
Non-same store/other (2) (3)		8,832		2,309		2,573		1,378		(271	)		14,821
Total rental income		161,821		84,475		91,962		106,346		(271	)		444,333
Operating expenses:
Same store (1)		57,136		30,498		36,054		38,143		—			161,831
Non-same store/other (2) (3)		4,407		1,198		1,276		423		3,524			10,828
Total operating expenses		61,543		31,696		37,330		38,566		3,524			172,659
NOI:
Same store (1)		95,853		51,668		53,335		66,825		—			267,681
Non-same store/other (2) (3)		4,425		1,111		1,297		955		(3,795	)		3,993
Total NOI	$	100,278	$	52,779	$	54,632	$	67,780	$	(3,795	)	$	271,674

(1)	Same store primarily includes all properties acquired or completed and stabilized prior to April 1, 2010, less properties subsequently sold, which represented 105,730 apartment units.
(2)	Non-same store primarily includes properties acquired after April 1, 2010, plus any properties in lease-up and not stabilized as of April 1, 2010.
(3)	Other includes development, condominium conversion overhead of $0.1 million and other corporate operations.

Note: Markets included in the above geographic segments are as follows:

(a) Northeast – New England (excluding Boston), Boston, New York Metro, DC Northern Virginia and Suburban Maryland.

(b) Northwest – Denver, Portland, San Francisco Bay Area and Seattle/Tacoma.

(c) Southeast – Atlanta, Jacksonville, Orlando, South Florida and Tampa.

(d) Southwest – Albuquerque, Inland Empire, Los Angeles, Orange County, Phoenix and San Diego.

Reconciliation of NOI

	Six Months Ended June 30,						Quarter Ended June 30,
	2011			2010			2011			2010
Rental income	$	974,096		$	871,091		$	496,111		$	444,333
Property and maintenance expense		(211,418	)		(202,801	)		(103,092	)		(100,045	)
Real estate taxes and insurance expense		(110,332	)		(105,496	)		(56,701	)		(52,350	)
Property management expense		(43,148	)		(40,756	)		(20,767	)		(20,264	)
Total operating expenses		(364,898	)		(349,053	)		(180,560	)		(172,659	)
Net operating income	$	609,198		$	522,038		$	315,551		$	271,674