Unsecured Revolving Credit Facility (Change In The Operating Partnership's Unsecured Debt Ratings) (Details)	6 Months Ended
	Jun. 30, 2012
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