Investments in Real Estate Entities (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Assets:
Real estate, net	$ 2,112,739,000		$ 1,337,084,000
Other assets	779,722,000		73,252,000
Total assets	2,892,461,000		1,410,336,000
Liabilities and partners' capital:
Mortgage notes payable and credit facility	1,391,811,000		943,259,000
Other liabilities	36,351,000		20,405,000
Partners' capital	1,464,299,000		446,672,000
Total liabilities and partners' capital	2,892,461,000		1,410,336,000
Combined summary of the operating results of the accounted for using the equity method
Rental and other income	43,827,000	42,627,000
Operating and other expenses	(17,705,000)	(18,669,000)
Gain on sale of communities	54,051,000	8,909,000
Interest expense, net	(15,269,000)	(13,066,000)
Depreciation expense	(13,151,000)	(12,700,000)
Net income (loss)	51,753,000	7,101,000
Abandoned Pursuit Costs and Impairment of Long-lived Assets
Expensed costs related to abandoned pursuits	245,000	147,000
Fund I and II
Combined summary of the operating results of the accounted for using the equity method
Costs in excess of equity in underlying net assets of the respective investments	6,726,000		7,342,000
Maximum amount that will be paid for capital contributions made by partners (as a percent)	10.00%
AvalonBay Value Added Fund, L.P.
Combined summary of the operating results of the accounted for using the equity method
Maximum amount that will be paid for capital contributions made by partners	7,500,000
AvalonBay Value Added Fund II, L.P
Combined summary of the operating results of the accounted for using the equity method
Maximum amount that will be paid for capital contributions made by partners	$ 8,910,000