Summary Of Significant Accounting Policies (Calculation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Accounting Policies [Abstract]
Basic earnings per common share, Income (Numerator)	$ 50,743	$ 49,232	$ 150,263	$ 160,563
Basic earnings per common share, Shares (Denominator)	173,429	181,718	174,869	184,030
Basic earnings per common share, Per Share Amount	$ 0.29	$ 0.27	$ 0.86	$ 0.87
Dilutive effect of stock options, Income (Numerator)	0	0	0	0
Dilutive effect of stock options, Shares (Denominator)	1,940	862	1,448	2,002
Diluted earnings per common share, Income (Numerator)	$ 50,743	$ 49,232	$ 150,263	$ 160,563
Diluted earnings per common share, Shares (Denominator)	175,369	182,580	176,317	186,032
Diluted earnings per common share, Per Share Amount	$ 0.29	$ 0.27	$ 0.85	$ 0.86