Pension Plans And Other Post-Retirement Benefits (Components Of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,718	$ 3,249	$ 3,174
Interest cost	11,817	11,495	12,434
Expected return on plan assets	(15,272)	(18,211)	(17,077)
Amortization of prior service cost (credit)	620	527	579
Amortization of actuarial loss	7,927	7,291	8,003
Settlement loss		5,931
Net periodic benefit cost	7,810	10,282	7,113
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	819	1,049	1,020
Interest cost	2,999	2,831	2,947
Expected return on plan assets	(2,482)	(2,706)	(2,589)
Amortization of prior service cost (credit)	(464)	(509)	(509)
Amortization of actuarial loss	664	1,182	1,165
Net periodic benefit cost	$ 1,536	$ 1,847	$ 2,034