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Investments in Real Estate Entities (Details) (USD $)
 3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Dec. 31, 2011
Investment in Real Estate Entities          
Proportionate share of gain on sale of communities $ 2,073,000 $ 395,000 $ 4,248,000 $ 898,000  
Assets:          
Real estate, net 1,544,617,000   1,544,617,000   1,583,397,000
Other assets 84,127,000   84,127,000   70,233,000
Total assets 1,628,744,000   1,628,744,000   1,653,630,000
Liabilities and partners' capital:          
Mortgage notes payable and credit facility 1,077,716,000   1,077,716,000   1,074,429,000
Other liabilities 22,320,000   22,320,000   27,335,000
Partners' capital 528,708,000   528,708,000   551,866,000
Total liabilities and partners' capital 1,628,744,000   1,628,744,000   1,653,630,000
Combined summary of the operating results of the accounted for using the equity method          
Rental and other income 44,505,000 38,632,000 87,132,000 76,454,000  
Operating and other expenses (19,131,000) (17,090,000) (37,800,000) (34,644,000)  
Gain on sale of communities 3,825,000   12,735,000    
Interest expense, net (12,659,000) (12,478,000) (25,726,000) (24,779,000)  
Depreciation expense (12,597,000) (11,737,000) (25,297,000) (23,339,000)  
Net income (loss) 3,943,000 (2,673,000) 11,044,000 (6,308,000)  
Abandoned Pursuit Costs and Impairment of Long-Lived Assets          
Expensed costs related to abandoned pursuits 820,000 395,000 968,000 1,045,000  
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 8,389,000   8,389,000   9,167,000
Maximum amount that will be paid for capital contributions made by partners (as a percent)     10.00%    
Fund I
          
Investment in Real Estate Entities          
Number of apartment homes sold 256        
Proceeds from sale of unconsolidated real estate entities 35,450,000        
Proportionate share of gain on sale of communities 385,000        
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   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   8,910,000    
Unconsolidated real estate entities
          
Investment in Real Estate Entities          
Number of unconsolidated real estate entities     5    
Unconsolidated real estate entities | Minimum
          
Investment in Real Estate Entities          
Ownership interest percentage 15.20%   15.20%    
Unconsolidated real estate entities | Maximum
          
Investment in Real Estate Entities          
Ownership interest percentage 31.30%   31.30%    
Eaves Cerritos
          
Investment in Real Estate Entities          
Purchase price $ 29,500,000   $ 29,500,000    
Number of apartment homes acquired     151