Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net income		$ 198,077	$ 107,887	$ 371,092	$ 194,476
Preferred dividends		8,289	4,843	16,578	9,687
Net income available to common shareholders		$ 189,788	$ 103,044	$ 354,514	$ 184,789
Average shares used in basic computation		107,837	105,791	107,795	106,358
Dilutive effect of stock options and units	[1]	10,765	5,790	10,484	7,119
Average shares used in diluted computation		118,602	111,581	118,279	113,477
Basic		$ 1.76	$ 0.97	$ 3.29	$ 1.74
Diluted		$ 1.60	$ 0.92	$ 3.00	$ 1.63

[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.