Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income		$ 192,376	$ 120,527	$ 563,468	$ 315,003
Preferred dividends		9,689	9,897	26,267	19,584
Net income available to common shareholders		$ 182,687	$ 110,630	$ 537,201	$ 295,419
Average shares used in basic computation		107,379	105,941	107,655	106,221
Dilutive effect of stock options and units	[1]	11,096	7,835	10,700	7,347
Average shares used in diluted computation		118,475	113,775	118,355	113,568
Basic		$ 1.70	$ 1.04	$ 4.99	$ 2.78
Diluted		$ 1.54	$ 0.97	$ 4.54	$ 2.60

[1] Diluted earnings per share is computed on the basis of the weighted-average number of shares of common stock plus the effect of dilutive potential common shares outstanding during the period using the treasury stock method.