Changes in Stockholders' Equity (Detail) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011
Beginning Balance	$ 3,315,591
Net income attributable to common stockholders	73,713
Unrealized loss on cash flow hedges	(19,420)
Change in redemption value of redeemable noncontrolling interest	(1,218)
Noncontrolling interests	(910)	[1]
Dividends declared to common stockholders	(157,075)
Issuance of common stock, net of withholdings	249,999
Amortization of deferred compensation	18,483
Ending Balance	3,479,163
Common stock
Beginning Balance	859
Issuance of common stock, net of withholdings	28
Ending Balance	887
Additional paid-in capital
Beginning Balance	3,593,677
Issuance of common stock, net of withholdings	251,060
Amortization of deferred compensation	18,483
Ending Balance	3,863,220
Accumulated earnings less dividends
Beginning Balance	(282,743)
Net income attributable to common stockholders	73,713
Change in redemption value of redeemable noncontrolling interest	(1,218)
Dividends declared to common stockholders	(157,075)
Issuance of common stock, net of withholdings	(1,089)
Ending Balance	(368,412)
Accumulated other comprehensive loss
Beginning Balance	(1,175)
Unrealized loss on cash flow hedges	(19,420)
Ending Balance	(20,595)
Total AvalonBay stockholders' equity
Beginning Balance	3,310,618
Net income attributable to common stockholders	73,713
Unrealized loss on cash flow hedges	(19,420)
Change in redemption value of redeemable noncontrolling interest	(1,218)
Dividends declared to common stockholders	(157,075)
Issuance of common stock, net of withholdings	249,999
Amortization of deferred compensation	18,483
Ending Balance	3,475,100
Noncontrolling interests
Beginning Balance	4,973
Noncontrolling interests	(910)	[1]
Ending Balance	$ 4,063

[1] Represents the impact of consolidating a Fund I subsidiary. See Note 6, "Investments in Real Estate Entities.