Pension Plans And Other Post-Retirement Benefits (Schedule Of Changes In Benefit Obligation And Fair Value Of Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Change in plan assets:
Settlements	$ (3,300)
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at January 1	452,947	$ 486,219
Service cost	2,587	3,503	$ 3,775
Interest cost	13,806	13,018	13,710
Actuarial (gain)/loss	(105,107)	(17,378)
Plan participants' contributions
Benefits paid	(19,339)	(32,415)
Plan amendments	2,121
Participants' directed transfer of benefit to other plans	(4,568)
Settlements	(17,757)
Benefit obligation at December 31	324,690	452,947	486,219
Change in plan assets:
Fair value of plan assets at January 1	433,121	426,801
Actual return on plan assets	(83,297)	23,901
Employer contributions	20,390	14,834
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant
Benefits paid	(19,281)	(32,415)
Settlements	(17,757)
Fair value of plan assets at December 31	333,176	433,121	426,801
Funded status of plan:
Net liability recognized at December 31,	8,486	(19,826)
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at January 1	114,651	125,375
Service cost	1,911	2,793	2,276
Interest cost	3,369	3,358	3,687
Actuarial (gain)/loss	(31,995)	(12,001)
Plan participants' contributions	145	36
Benefits paid	(4,580)	(4,910)
Plan amendments
Participants' directed transfer of benefit to other plans
Settlements
Benefit obligation at December 31	83,501	114,651	125,375
Change in plan assets:
Fair value of plan assets at January 1	107,308	98,995
Actual return on plan assets	(19,589)	12,484
Employer contributions	1,636	598
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	145	36
Benefits paid	(3,506)	(4,805)
Settlements
Fair value of plan assets at December 31	85,994	107,308	$ 98,995
Funded status of plan:
Net liability recognized at December 31,	$ 2,493	$ (7,343)