CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Archstone Enterprise LP	Jun. 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)	1,030	1,336
Common stock issued through the dividend reinvestment plan	140,000	180,000
Stock issued in connection with stock grants (in shares)	123,977	95,941
Stock issued in connection with stock grants, value	16,019,000	12,786,000
Number of shares withheld to satisfy employees' tax withholding and other liabilities	44,222	120,078
Shares withheld to satisfy employees' tax withholding and other liabilities, value	5,638,000	15,458,000
Number of shares forfeited	5,214	7,558
Shares cancelled upon forfeiture	516,000	393,000
Number of options granted for common stock	215,230	113,804
Options granted for common stock, value	5,768,000	3,306,000
Decrease in interest expense, net	2,484,000
Common dividends declared but not paid	138,456,000	93,698,000
Decrease in other comprehensive income due to a change in other liabilities		16,789,000
Cash flow hedge losses reclassified to interest expense, net	2,965,000
Increase (decrease) in prepaid expenses and other assets due to hedge accounting		(11,000)
Increase in redeemable noncontrolling interests	$ 329,000	$ 521,000