Retirement Benefits (Summary Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,738	$ 2,041	$ 5,476	$ 6,052
Interest cost	1,999	2,563	3,998	5,046
Expected return on plan assets	(5,580)	(5,197)	(11,161)	(10,394)
Amortization of net (income) loss	2,731	2,462	5,461	3,675
Net periodic benefit cost	1,888	1,869	3,774	4,379
Post-Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	281	311	564	452
Interest cost	181	215	362	429
Amortization of prior service cost	(144)	(176)	(289)	(224)
Net periodic benefit cost	$ 318	$ 350	$ 637	$ 657