Benefit Plans (Schedule Of Benefit Plans) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Costs
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 498	$ 496	$ 996	$ 992
Interest cost	1,241	1,385	2,482	2,769
Expected return on plan assets	(1,502)	(1,389)	(3,004)	(2,777)
Net cost	237	492	474	984
Postretirement Costs
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	0	1
Interest cost	251	241	502	483
Net cost	$ 251	$ 242	$ 502	$ 484