CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Archstone Enterprise LP	Sep. 30, 2012 4.61% Fixed Rate Mortgage Loan
Supplemental disclosures of non-cash investing and financing activities
Mortgage notes assumed				$ 11,958,000
Stated interest rate (as a percent)				4.61%
Obligation related to outstanding preferred interests			66,500,000
Increase in redeemable noncontrolling interests associated with business acquisition			13,262,000
Value of shares of common stock issued as partial consideration for acquisition			1,875,210,000
Assumed principal amount of indebtedness			3,512,202,000
Number of shares of common stock issued as partial consideration for acquisition			14,889,706
Common stock issued through the dividend reinvestment plan (in shares)	1,465	1,830
Common stock issued through the dividend reinvestment plan	200,000	254,000
Stock issued in connection with stock grants (in shares)	123,977	96,592
Stock issued in connection with stock grants, value	16,019,000	12,883,000
Number of shares withheld to satisfy employees' tax withholding and other liabilities	44,750	120,952
Shares withheld to satisfy employees' tax withholding and other liabilities, value	5,706,000	15,491,000
Number of shares forfeited	5,214	7,558
Shares cancelled upon forfeiture	780,000	393,000
Number of options granted for common stock	215,230	115,303
Options granted for common stock, value	5,768,000	3,357,000
Common dividends declared but not paid	138,459,000	94,778,000
Decrease in other comprehensive income due to a change in other liabilities		23,767,000
Deferred cash flow hedge losses reclassified to interest expense, net	4,429,000
Deferred cash flow hedge losses reclassified to loss on interest rate contract	53,484,000
Increase (decrease) in prepaid expenses and other assets due to hedge accounting		(11,000)
Increase in redeemable noncontrolling interests	$ 441,000	$ 480,000