Retirement Plans (Schedule Of Net Funded Status And Accumulated Benefit Obligation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retirement Plans [Abstract]
Projected benefit obligation at beginning of year	$ 40,470	$ 41,384	$ 37,016
Service cost	1,447	1,533	1,386
Interest cost	1,785	1,587	1,590
Benefits paid	(1,985)	(1,574)	(1,510)
Assumption changes	5,200	(3,226)	2,100
Experience loss and other	554	766	802
Projected benefit obligation at end of year	47,471	40,470	41,384
Fair value of plan assets at beginning of year	55,624	60,536	54,332
Actual return on plan assets	11,854	(3,563)	7,497
Plan participant contributions	356	333	321
Benefits paid	(1,985)	(1,574)	(1,510)
Expenses	(103)	(108)	(104)
Fair value of plan assets at end of year	65,746	55,624	60,536
Funded status at end of year	18,275	15,154	19,152
Accumulated benefit obligation	$ 44,544	$ 38,042	$ 38,544