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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income	$ 52,811	$ 9,771	$ 118,323	$ 36,826
Preferred dividends	2,344		4,688
Net income available to common shareholders	$ 50,467	$ 9,771	$ 113,635	$ 36,826
Average shares used in basic computation	68,556	66,792	68,471	67,186
Dilutive effect of stock options and units	11,465	9,190	11,920	8,898
Average shares used in diluted computation	80,021	75,982	80,391	76,084
Basic	$ 0.74	$ 0.15	$ 1.66	$ 0.55
Diluted	$ 0.63	$ 0.13	$ 1.41	$ 0.48