Archstone Acquisition (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended	3 Months Ended	4 Months Ended	6 Months Ended		0 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Feb. 27, 2013 Archstone	Jun. 30, 2013 Archstone	Jun. 30, 2013 Archstone	Jun. 30, 2013 Archstone	Jun. 30, 2012 Archstone	Feb. 27, 2013 Archstone Apartment communities	Feb. 27, 2013 Archstone Equity
Archstone Acquisition
Percentage of assets and liabilities acquired					40.00%						60.00%
Land and land improvements					$ 1,760,100,000
Buildings and improvements					3,729,422,000
FF&E					52,290,000
Construction-in-progress, including land and land held for development					404,765,000
In-place lease intangibles					182,467,000
Other assets					85,829,000
Total consolidated assets					6,214,873,000
Interest in unconsolidated real estate entities					256,454,000
Total assets					6,471,327,000
Fair value of assumed mortgage notes payable					3,732,980,000
Liability for preferred obligations					66,500,000
Other liabilities					34,100,000
Noncontrolling interest					13,262,000
Net Assets Acquired					2,624,485,000
Common shares issued					1,875,210,000
Cash consideration					749,275,000
Acquisition related expenses
Acquisition related expenses recognized				163,000				77,939,000
Acquisition related expenses reported as a component of equity in income (loss) of unconsolidated entities	(940,000)	2,073,000	(19,503,000)	4,248,000				34,552,000
Consideration
Number of shares issued					14,889,706			14,889,706
Value of shares issued					1,875,210,000
Cash payment					749,275,000
Fair value of indebtedness assumed					3,732,979,000
Principal amount of consolidated indebtedness					3,512,202,000	3,512,202,000	3,512,202,000	3,512,202,000
Debt fair value exceeds the principal face value					220,777,000
Redemption value of preferred equity					66,500,000	66,500,000	66,500,000	66,500,000
Preferred redemption obligations proportionate share paid						32,100,000
Information for acquisition that is included in condensed consolidated statement of operations comprehensive income from the acquisition date
Revenues	389,234,000	252,445,000	699,600,000	496,820,000			140,196,000
Loss attributable to common shareholders	36,218,000	156,909,000	111,648,000	214,667,000			(91,137,000)
Supplemental consolidated pro forma information
Revenues								771,547,000	695,464,000
Income (loss) from continuing operations								198,262,000	(24,486,000)
Earnings (loss) per common share - diluted (from continuing operations)								$ 1.53	$ (0.19)
Lease-up period assumed to achieve stabilized occupancy										12 months
Depreciation expense for in-place lease intangibles						93,726,000		124,601,000
Debt fair value exceeds the principal face value relating to debt repaid					$ 70,479,000