| Schedule Of Stock Option Plans | 
        
|    | 
   | 
 Weighted 
 | 
 Aggregate 
 | 
 
|    | 
 Shares 
 | 
 Average 
 | 
 Intrinsic 
 | 
 
|    | 
 Under 
 | 
 Exercise 
 | 
 Value 
 | 
 
|    | 
 Options 
 | 
 Price 
 | 
 $(000's) 
 | 
 
| 
 Outstanding  as January 1, 2011 
 | 
 295,676 
 | 
 $29.05 
 | 
 $1,186 
 | 
 
| 
 Exercised 
 | 
 (53,010) 
 | 
 $27.60 
 | 
   | 
 
| 
 Outstanding at June 30, 2011 ($28.47 – $45.47) 
 | 
 242,666 
 | 
 $29.37 
 | 
 $      867 
 | 
 
| 
 Options exercisable at June 30, 2011 
 | 
 242,666 
 | 
   | 
   | 
 
| 
 Available for grant at June 30, 2011 
 | 
 2,425,073 
 | 
   | 
   | 
 
 
 | 
      
      
        | Schedule Of Basic And Diluted Earnings Per Share | 
        
 | 
      
      
        | Schedule Of Reconciliation Of Shares Used In Basic EPS Calculation To Shares Used In Diluted EPS Calculation | 
        
|   | 
  | 
  | 
  | 
  | 
 
| 
   
 | 
 Three Months Ended 
 | 
 Six Months Ended 
 | 
 
| 
   
 | 
 June 30, 
 | 
 June 30, 
 | 
 
| 
   
 | 
 2011 
 | 
 2010 
 | 
 2011 
 | 
 2010 
 | 
 
| 
 Basic EPS shares 
 | 
 86,936 
 | 
 79,203 
 | 
 84,953 
 | 
 79,089 
 | 
 
| 
 Add:Operating Partnership – common units 
 | 
 12,840 
 | 
 13,155 
 | 
 12,896 
 | 
 13,259 
 | 
 
| 
 Stock options 
 | 
 37 
 | 
 52 
 | 
 40 
 | 
 54 
 | 
 
| 
 Restricted Stock Awards 
 | 
 74 
 | 
 79 
 | 
 74 
 | 
 80 
 | 
 
| 
 Diluted EPS Shares 
 | 
 99,887 
 | 
 92,489 
 | 
 97,963 
 | 
 92,482 
 | 
 
 
 |