Income Per Share (Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities	15,684,535	21,863,563	20,625,120	21,504,743
Weighted Average Of Operating Partnership Common Units Not Owned By Us [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities	2,549,749	4,345,574	2,515,964	4,346,586
Potentially Dilutive 2029 Debentures [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities		6,514,812	6,628,489	6,471,282
Potentially Dilutive Series C Cumulative Convertible Preferred Stock/Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities				1,087,398
Potentially Dilutive Series D Cumulative Convertible Preferred Stock/Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities		4,219,384	629,389	4,309,978
Potentially Dilutive Series E Cumulative Redeemable Preferred Stock/Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities	5,251,059	4,151,146	4,853,976	4,045,501
Potentially Dilutive Series F Cumulative Redeemable Preferred Stock/Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities	3,330,210	2,632,647	3,078,381	1,243,998
Potentially Dilutive Series G Cumulative Redeemable Preferred Stock/Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities	4,153,208		2,918,921