Indebtedness (Unsecured Line of Credit) (Details) (Unsecured Line of Credit DRLP [Member], USD $)	6 Months Ended
	Jun. 30, 2014
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,250,000,000
Line of Credit Facility, Covenant Compliance	we were in compliance with all covenants under this line of credit.
Current Market Rate Of Unsecured Lines Of Credit	1.41%
Borrowing capacity of unsecured line of credit	850,000,000
Maturity date	Dec. 01, 2015
Line of Credit Facility Increase	400,000,000
Line of credit balance	$ 60,000,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Description of Variable Rate Basis	LIBOR
Debt Instrument, Basis Spread on Variable Rate	1.25%
Line of Credit Facility, Interest Rate at Period End	1.40%