Unsecured Revolving Credit Facility (Change In The Operating Partnership's Unsecured Debt Ratings) (Details)	12 Months Ended
	Dec. 31, 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	1.85%
Facility Fee Basis Points	0.45%
BBB- Or Baa3 [Member]
Guarantor Obligations [Line Items]
Unsecured Debt Ratings	BBB- or Baa3
Interest Rate - Applicable Basis Points Above LIBOR	1.50%
Facility Fee Basis Points	0.35%
BBB Or Baa2 (Current) [Member]
Guarantor Obligations [Line Items]
Unsecured Debt Ratings	BBB or Baa2(current)
Interest Rate - Applicable Basis Points Above LIBOR	1.25%
Facility Fee Basis Points	0.25%
BBB+ Or Baa1 [Member]
Guarantor Obligations [Line Items]
Unsecured Debt Ratings	BBB+or Baa1
Interest Rate - Applicable Basis Points Above LIBOR	1.075%
Facility Fee Basis Points	0.20%
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	1.00%
Facility Fee Basis Points	0.175%