| 
           Unsecured Revolving Credit Facility (Change In The Operating Partnership's Unsecured Debt Ratings) (Details) 
         | 
        6 Months Ended | |||
|---|---|---|---|---|
| 
           Jun. 30, 2011 
         | 
      ||||
| Unsecured Debt Ratings | BBB/Baa2 | |||
| Facility Fee Basis Points | 15 | |||
| 
           No Ratings Or Less Than BBB-/Baa3/BBB- [Member] 
         | 
        ||||
| Unsecured Debt Ratings | No ratings or less than BBB-/Baa3/BBB- | [1] | ||
| Interest Rate - Applicable Basis Points Above LIBOR | 100.0 | [1] | ||
| Facility Fee Basis Points | 25.0 | [1] | ||
| 
           BBB-/Baa3/BBB- [Member] 
         | 
        ||||
| Unsecured Debt Ratings | BBB-/Baa3/BBB- | [1] | ||
| Interest Rate - Applicable Basis Points Above LIBOR | 75.0 | [1] | ||
| Facility Fee Basis Points | 20.0 | [1] | ||
| 
           BBB/Baa2/BBB (Current) [Member] 
         | 
        ||||
| Unsecured Debt Ratings | BBB/Baa2/BBB (current) | [1] | ||
| Interest Rate - Applicable Basis Points Above LIBOR | 55.0 | [1] | ||
| Facility Fee Basis Points | 15.0 | [1] | ||
| 
           BBB+/Baa1/BBB+ [Member] 
         | 
        ||||
| Unsecured Debt Ratings | BBB+/Baa1/BBB+ | [1] | ||
| Interest Rate - Applicable Basis Points Above LIBOR | 42.5 | [1] | ||
| Facility Fee Basis Points | 15.0 | [1] | ||
| 
           A-/A3/A- Or Higher [Member] 
         | 
        ||||
| Unsecured Debt Ratings | A-/A3/A- or higher | [1] | ||
| Interest Rate - Applicable Basis Points Above LIBOR | 37.5 | [1] | ||
| Facility Fee Basis Points | 12.5 | [1] | ||
          
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