Condensed Consolidated Statements Of Equity (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Common dividend per share	$ 0.305	$ 0.290
6.75% Series D Preferred Shares [Member]
Preferred dividend per share	$ 13.08	$ 12.66
6.95% Series E Preferred Shares [Member]
Preferred dividend per share	$ 0.00	$ 43.44
6.5% Series F Preferred Shares [Member]
Preferred dividend per share	$ 40.63	$ 40.63