Equity, Capital and Other Interests Text (Details) (USD $)	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Mar. 31, 2013 Archstone Transaction [Member]	Sep. 30, 2014 Partially Owned Properties [Member]	Sep. 30, 2014 Enclave at Wellington [Domain]
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
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)
Properties acquired	4		1
Number of Units in Real Estate Property	111,087		3,771	268
Land parcels acquired	2		1
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