Subsequent Events (Details) (USD $)	3 Months Ended				9 Months Ended	3 Months Ended		9 Months Ended	3 Months Ended
	Dec. 31, 2014 Declaration of Dividends [Member]	Dec. 31, 2014 Declaration of Dividends [Member] Common Stock [Member]	Dec. 31, 2014 Declaration of Dividends [Member] Series K Preferred Stock [Member]	Dec. 31, 2014 Declaration of Dividends [Member] Series L Preferred Stock [Member]	Sep. 30, 2014 Unsecured Line of Credit DRLP [Member]	Dec. 31, 2014 Unsecured Line of Credit DRLP [Member] Subsequent Event [Member]	Oct. 09, 2014 Unsecured Line of Credit DRLP [Member] Subsequent Event [Member]	Sep. 30, 2014 London Interbank Offered Rate (LIBOR) [Member] Unsecured Line of Credit DRLP [Member]	Dec. 31, 2014 London Interbank Offered Rate (LIBOR) [Member] Unsecured Line of Credit DRLP [Member] Subsequent Event [Member]	Dec. 31, 2014 Variable Rate UnSecured Debt [Member] [Member] London Interbank Offered Rate (LIBOR) [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Expiration Date					Dec. 01, 2015	Jan. 01, 2019
Line of Credit Facility, Current Borrowing Capacity					$ 850,000,000		$ 1,200,000,000
Line of Credit Facility Increase					400,000,000
Line of Credit Facility, Maximum Borrowing Capacity					$ 1,250,000,000		$ 1,600,000,000
Debt Instrument, Description of Variable Rate Basis								LIBOR	LIBOR	LIBOR
Debt Instrument, Basis Spread on Variable Rate								1.25%	1.05%	1.15%
Debt Instrument, Maturity Date						Jan. 01, 2019
Common stock dividends declared per share		$ 0.17
Preferred stock dividends declared per share			$ 0.406250	$ 0.412500
Record date		Nov. 14, 2014	Nov. 14, 2014	Nov. 14, 2014
Payment date		Nov. 28, 2014	Nov. 28, 2014	Nov. 28, 2014
Declared date	Oct. 29, 2014