Benefit Plans (Schedule Of Benefit Plans) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Costs
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 498	$ 496
Interest cost	1,241	1,385
Expected return on plan assets	(1,502)	(1,389)
Net cost	237	492
Postretirement Costs
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1
Interest cost	251	241
Net cost	$ 251	$ 242