Unsecured Revolving Credit Facility (Change In The Operating Partnership's Unsecured Debt Ratings) (Details)
12 Months Ended
Dec. 31, 2011
No Ratings Or Less Than BBB-/Baa3 [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings No ratings or less than BBB-/Baa3
Interest Rate - Applicable Basis Points Above LIBOR 185.0
Facility Fee Basis Points 45.0
BBB- Or Baa3 [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings BBB- or Baa3
Interest Rate - Applicable Basis Points Above LIBOR 150.0
Facility Fee Basis Points 35.0
BBB Or Baa2 (Current) [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings BBB or Baa2(current)
Interest Rate - Applicable Basis Points Above LIBOR 125.0
Facility Fee Basis Points 25.0
BBB+ Or Baa1 [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings BBB+or Baa1
Interest Rate - Applicable Basis Points Above LIBOR 107.5
Facility Fee Basis Points 20.0
A- Or A3 Or Higher [Member]
 
Guarantor Obligations [Line Items]  
Unsecured Debt Ratings A-or A3 or higher
Interest Rate - Applicable Basis Points Above LIBOR 100.0
Facility Fee Basis Points 17.5