v2.4.0.6
Stockholders' Equity (Details) (USD $)
 12 Months Ended 1 Months Ended 12 Months Ended 26 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
Archstone Enterprise LP
Dec. 31, 2012
CEP II and CEP III
Nov. 30, 2010
CEP II
Dec. 31, 2012
CEP II
Dec. 31, 2012
CEP II
Aug. 31, 2012
CEP III
Dec. 31, 2012
CEP III
Equity                    
Common stock, shares authorized 140,000,000 140,000,000                
Preferred stock, shares authorized 50,000,000 50,000,000                
Common stock shares issued       16,675,000 18,840,206   1,435,215 3,925,980   729,991
Common stock shares issued in connection with stock options exercised 407,784                  
Common stock shares issued through dividend reinvestment plan 2,331 3,343 5,687              
Common stock shares issued in connection with stock grants 96,592 511,817 102,984              
Number of shares of stock grants withheld 121,351 129,762 48,882              
Restricted common stock shares forfeited 4,027                  
Common stock shares issued for Employee Stock Purchase Plan 6,260                  
Options of common stock granted to employees (in shares) 115,303                  
Common stock shares issued, offer price (in dollars per share)       $ 130.00            
Net proceeds from common stock shares issued $ 2,414,775,000 $ 1,035,302,000 $ 380,973,000 $ 2,102,718,000            
Maximum value of shares of common stock that can be sold (in dollars)           500,000,000     750,000,000  
Period during which common stock can be sold           36 months     36 months  
Percentage of compensation received by sales agent                   1.50%
Shares sold, average sales price (in dollars per share)             $ 140.41 $ 127.36   $ 142.09
Net proceeds from sales of shares (in dollars) $ 2,430,190,000 $ 1,049,835,000 $ 381,365,000       $ 198,489,000 $ 492,490,000   $ 102,168,000