Equity, Capital and Other Interests Text (Details) (USD $)	3 Months Ended	6 Months Ended
	Mar. 31, 2013	Jun. 30, 2014
Additional Common Shares Authorized		13,000,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased		13,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased		12,968,760
Stock Repurchased And Retired		(31,240)
Treasury Stock Acquired, Average Cost Per Share		$ 56.87
Value Of Stock Repurchased And Retired		$ 1,800,000
OP Units repurchased and retired		31,240
Number of Units in Real Estate Property		111,491
Payments to Acquire Interest in Subsidiaries and Affiliates		5,500,000
Increase To Reduction Of Paid In Capital		2,300,000
Reduction In Partially Owned Properties		2,200,000
Reduction In Other Liabilities		1,000,000
Archstone Transaction [Member]
Issuance of Common Shares	34,468,085
Stock Issued During Period, Value, New Issues	$ 1,900,000,000
Average Price Per Common Share Issued	$ 55.99
Units Issued During Period New Issues		34,468,085
Enclave at Wellington [Domain]
Number of Units in Real Estate Property		268