Subsequent Events (Schedule Of Dividends Declared And Distributions Per Unit) (Details) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2012	Apr. 23, 2012 Series D Preferred Stock [Member]	Apr. 23, 2012 Series E Preferred Stock [Member]	Apr. 23, 2012 Series F Preferred Stock [Member]		Apr. 23, 2012 Common Stock And Common Unit [Member]
Subsequent Event [Line Items]
Dividend and distribution amount		$ 0.343750	$ 0.437500	$ 0.395660	[1]	$ 0.730000
Dividend and distribution payable date	Mar. 30, 2012	Jun. 29, 2012	Jun. 29, 2012	Jun. 29, 2012		Jun. 29, 2012
Dividend payable to shareholders of record on		Jun. 15, 2012	Jun. 15, 2012	Jun. 15, 2012		Jun. 15, 2012
Annual equivalent rate of dividend and distribution		$ 1.375	$ 1.750	$ 1.65625		$ 2.920

[1] Represents a pro rata dividend from and including the original issue date to and including June 30, 2012.