CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Supplemental disclosures of non-cash investing and financing activities
Assumed principal amount of indebtedness	$ 3,512,202,000
Number of shares of common stock issued as partial consideration for acquisition	14,889,706
Value of shares of common stock issued as partial consideration for acquisition	1,875,210,000
Common stock issued through the dividend reinvestment plan (in shares)	550	735
Common stock issued through the dividend reinvestment plan	76,000	95,000
Stock issued in connection with stock grants (in shares)	119,292	91,471
Stock issued in connection with stock grants, value	15,394,000	12,161,000
Number of shares withheld to satisfy employees' tax withholding and other liabilities	29,219	39,054
Shares withheld to satisfy employees' tax withholding and other liabilities, value	3,590,000	5,119,000
Number of shares forfeited	9,226	4,027
Shares forfeited, value	780,000	324,000
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	1,414,000
Common dividends declared but not paid	138,438,000	92,508,000
Increase in redeemable noncontrolling interests associated with business acquisition	13,262,000
Increase in other comprehensive income due to a change in other liabilities		11,008,000
Cash flow hedge losses reclassified to interest expense, net	1,391,000
Decrease in prepaid expenses and other assets due to hedge accounting		11,000
Increase in redeemable noncontrolling interests	526,000	309,000
Archstone Enterprise LP
Supplemental disclosures of non-cash investing and financing activities
Obligation related to outstanding preferred interests	66,500,000
Assumed principal amount of indebtedness	3,512,202,000
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%