Reportable Segments (Tables)

3 Months Ended

9 Months Ended

Mar. 31, 2013

Sep. 30, 2012

Reportable Segments (Tables) [Abstracts]

Reportable Segments Schedule

	Quarter Ended March 31, 2013
	Northeast		Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	186,839	$	102,570	$	64,678	$	111,566	$	—		$	465,653
Non-same store/other (2) (3)	43,702		17,389		256		8,100		1,902			71,349
Total rental income	230,541		119,959		64,934		119,666		1,902			537,002
Operating expenses:
Same store (1)	69,299		35,427		24,533		37,197		—			166,456
Non-same store/other (2) (3)	14,060		6,667		104		3,397		7,535			31,763
Total operating expenses	83,359		42,094		24,637		40,594		7,535			198,219
NOI:
Same store (1)	117,540		67,143		40,145		74,369		—			299,197
Non-same store/other (2) (3)	29,642		10,722		152		4,703		(5,633		)	39,586
Total NOI	$	147,182	$	77,865	$	40,297	$	79,072	$	(5,633	)	$	338,783
Total assets	$	11,571,120	$	4,745,161	$	1,707,027	$	3,925,524	$	1,846,326		$	23,795,158
Capital expenditures	$	9,030	$	8,137	$	3,799	$	3,993	$	1,640		$	26,599

(1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2012, less properties subsequently sold, which represented 90,350 apartment units.

(2) Non-same store primarily includes properties acquired after January 1, 2012, plus any properties in lease-up and not stabilized as of January 1, 2012.

(3) Other includes development and other corporate operations.

	Quarter Ended March 31, 2012
	Northeast			Northwest		Southeast		Southwest		Other (3)			Total
Rental income:
Same store (1)	$	178,867		$	95,144	$	61,778	$	107,363	$	—		$	443,152
Non-same store/other (2) (3)	404			722		—		87		19			1,232
Total rental income	179,271			95,866		61,778		107,450		19			444,384
Operating expenses:
Same store (1)	66,752			34,662		24,064		36,289		—			161,767
Non-same store/other (2) (3)	907			381		—		22		5,654			6,964
Total operating expenses	67,659			35,043		24,064		36,311		5,654			168,731
NOI:
Same store (1)	112,115			60,482		37,714		71,074		—			281,385
Non-same store/other (2) (3)	(503		)	341		—		65		(5,635		)	(5,732		)
Total NOI	$	111,612		$	60,823	$	37,714	$	71,139	$	(5,635	)	$	275,653

(1) Same store primarily includes all properties acquired or completed and stabilized prior to January 1, 2012, less properties subsequently sold, which represented 90,350 apartment units.

(2) Non-same store primarily includes properties acquired after January 1, 2012, plus any properties in lease-up and not stabilized as of January 1, 2012.

(3) Other includes development and other corporate operations.

Reconciliation of NOI

	Quarter Ended March 31,
	2013			2012
Rental income	$	537,002		$	444,384
Property and maintenance expense	(107,083		)	(92,952		)
Real estate taxes and insurance expense	(68,647		)	(52,440		)
Property management expense	(22,489		)	(23,339		)
Total operating expenses	(198,219		)	(168,731		)
Net operating income	$	338,783		$	275,653