Market And Dividend Information (Summary Of Common Stock Sales Price And Dividends Declared Per Share) (Details) (USD $)	3 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010
Dividends Payable [Line Items]
Dividend Declared	$ 0.90	$ 1.00	$ 1.00	$ 1.00	$ 1.00	$ 1.10	$ 1.10	$ 1.20
High [Member]
Dividends Payable [Line Items]
Sales Price	$ 27.31	$ 29.26	$ 29.39	$ 30.99	$ 31.98	$ 30.86	$ 30.03	$ 28.32
Low [Member]
Dividends Payable [Line Items]
Sales Price	$ 22.33	$ 23.80	$ 27.12	$ 27.88	$ 28.28	$ 26.73	$ 11.25	$ 23.81