v2.4.0.6
Organization, Basis of Presentation and Significant Accounting Policies (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 3 Months Ended 6 Months Ended
Jun. 30, 2012
community
home
state
Jun. 30, 2011
Jun. 30, 2012
community
home
state
Jun. 30, 2011
Organization and Basis of Presentation        
Number of operating apartment communities owned 181   181  
Number of apartment homes included in operating apartment communities owned 53,144   53,144  
Number of states where operating apartment communities owned are located 9   9  
Number of communities with apartments under reconstruction 11   11  
Number of apartment homes under reconstruction 2,721   2,721  
Number of owned communities under construction 20   20  
Expected number of apartment homes under construction 6,114   6,114  
Communities under development rights 33   33  
Estimated number of apartment homes in communities to be developed 9,036   9,036  
Basic and diluted shares outstanding        
Weighted average common shares - basic 95,308,163 87,317,602 95,082,172 86,746,992
Weighted average DownREIT units outstanding (in shares) 7,500 7,707 7,500 8,992
Effect of dilutive securities (in shares) 677,162 871,129 730,531 841,997
Weighted average common shares - diluted 95,992,825 88,196,438 95,820,203 87,597,981
Calculation of Earnings per Share - basic        
Net income attributable to common stockholders $ 156,909 $ 43,373 $ 214,667 $ 73,713
Net income allocated to unvested restricted shares (547) (123) (845) (206)
Net income attributable to common stockholders, adjusted 156,362 43,250 213,822 73,507
Weighted average common shares - basic 95,308,163 87,317,602 95,082,172 86,746,992
Earnings per common share - basic $ 1.64 $ 0.50 $ 2.25 $ 0.85
Calculation of Earnings per Share - diluted        
Net income attributable to common stockholders 156,909 43,373 214,667 73,713
Add: noncontrolling interests of Down REIT unitholders in consolidated partnerships, including discontinued operations 7 7 13 13
Adjusted net income attributable to common stockholders $ 156,916 $ 43,380 $ 214,680 $ 73,726
Weighted average common shares - diluted 95,992,825 88,196,438 95,820,203 87,597,981
Earnings per common share - diluted (in dollars per share) $ 1.63 $ 0.49 $ 2.24 $ 0.84
Options to purchase shares of common stock excluded from computation of earnings per share amount     424,357 320,698
Estimated forfeiture rate of stock options (as a percent)     0.30%