Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 99,207	$ 88,761
Preferred dividends	2,344	2,344
Net income available to common shareholders	$ 96,863	$ 86,417
Average shares used in basic computation	71,700	71,999
Dilutive effect of stock options and units	7,510	9,790
Average shares used in diluted computation	79,210	81,789
Basic	$ 1.35	$ 1.20
Diluted	$ 1.22	$ 1.06