Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Reconciliation of NOI to net income
Net income	$ 172,197		$ 36,097		$ 313,796		$ 111,570
Indirect operating expenses, net of corporate income	12,343		10,852		23,161		19,894
Investments and investment management expense	1,137		1,096		2,116		2,110
Expensed acquisition, development and other pursuit costs	2,017		3,806		2,732		43,865
Interest expense, net	43,722	[1]	43,169	[1]	86,255	[1]	81,342	[1]
Loss on extinguishment of debt, net	412		0		412		0
General and administrative expense	10,220		11,345		19,456		21,384
Equity in (income) loss of unconsolidated real estate entities	(7,710)		940		(12,933)		19,503
Depreciation expense	110,395	[1]	189,977	[1]	216,762	[1]	295,536	[1]
Gain (Loss) on Sale of Properties					98,814		118,413
Gain on sale of discontinued operations	0		(33,682)		(37,869)		(118,173)
Income from discontinued operations	0		(2,081)		(310)		(7,827)
Net operating income from real estate assets sold or held for sale, not classified as discontinued operations	(2,030)		(2,308)		(4,314)		(4,178)
Net operating income	281,758		258,971		548,319		464,786
Continuing Operations [Member]
Reconciliation of NOI to net income
Gain (Loss) on Sale of Properties	60,945		240		60,945		240
Net operating income	$ 281,758	[2]	$ 258,971		$ 548,319	[2]	$ 464,786

[1] Includes amounts associated with assets sold or held for sale, not classified as discontinued operations.

[2] Results for the three months ended June 30, 2014 reflect the operating segments updated as of April 1, 2014, which include most stabilized communities acquired as part of the Archstone Acquisition in the Established Communities segment. Results for the six months ended June 30, 2014 reflect the operating segments determined as of January 1, 2014, which include stabilized communities acquired as part of the Archstone Acquisition in the Other Stabilized segment.