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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 17,814	$ 17,179	$ 54,640	$ 81,164
Preferred dividends	1,563		1,563
Net income available to common shareholders	$ 16,251	$ 17,179	$ 53,077	$ 81,164
Average shares used in basic computation	66,482	69,633	66,950	68,675
Dilutive effect of stock options and units	11,062	10,126	9,662	9,651
Average shares used in diluted computation	77,544	79,759	76,612	78,326
Basic	$ 0.24	$ 0.25	$ 0.79	$ 1.18
Diluted	$ 0.21	$ 0.22	$ 0.69	$ 1.04