Earnings Per Common Share Computation (Schedule Of Details Supporting The Computation Of Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net income available for common stockholders	$ 444,760	$ 393,221	$ 1,220,223	$ 992,065
Weighted average outstanding shares of common stock used to compute basic earnings per common share	164,121	167,574	166,138	168,082
Shares used to compute diluted earnings per common share	166,580	169,582	168,558	169,964
Basic earnings per common share	$ 2.71	$ 2.35	$ 7.34	$ 5.90
Diluted earnings per common share	$ 2.67	$ 2.32	$ 7.24	$ 5.84
Number of antidilutive stock options and restricted stock excluded from computation	168	3,256	1,017	4,355
Employee Stock Options [Member]
Dilutive effect of employee stock options and restricted stock	895	634	962	589
Restricted Stock [Member]
Dilutive effect of employee stock options and restricted stock	1,564	1,374	1,458	1,293