Equity, Capital and Other Interests Text (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013 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	$ 56.87	$ 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)
Value Of Stock Repurchased And Retired	1,800,000
Payments to Acquire Interest in Subsidiaries and Affiliates	2,500,000
Increase To Reduction Of Paid In Capital	500,000
Reduction In Partially Owned Properties	1,000,000
Reduction In Other Liabilities	$ 1,000,000