Consolidated Statements of Equity (Parenthetical) Consolidated Statements of Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Dividend Per Depositary Share Of Series C Preferred Stock	$ 1.8438	$ 1.8438	$ 1.8438
Common Stock, Dividends, Per Share, Declared	$ 1.53	$ 1.513	$ 1.5
Stock Issued During Period, Shares, New Issues	17,288,265	39,872	99,738
Issuance of shares - discounted stock purchase program	3,197,127	431,705	3,664,182
Stock Issued During Period, Shares, Restricted Stock Award, Gross	133,432	377,164	262,546