Benefit Plan (Components Of Net Periodic Benefit Expense) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Pension plan contributions			$ 0	$ 0
Service cost	$ 1,559,000	$ 2,437,000	4,677,000	7,311,000
Interest cost	1,631,000	1,426,000	4,893,000	4,278,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(334,000)	(590,000)	(1,002,000)	(1,770,000)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1,559,000	2,437,000	4,677,000	7,311,000
Interest cost	1,631,000	1,426,000	4,893,000	4,278,000
Expected return on plan assets	(3,536,000)	(4,449,000)	(10,608,000)	(13,347,000)
Recognized net actuarial loss	12,000	(4,000)	36,000	(12,000)
Benefit expense	(334,000)	(590,000)	(1,002,000)	(1,770,000)
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	234,000	212,000	702,000	637,000
Interest cost	176,000	183,000	527,000	549,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	410,000	395,000	1,229,000	1,186,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	234,000	212,000	702,000	637,000
Interest cost	176,000	183,000	527,000	549,000
Benefit expense	$ 410,000	$ 395,000	$ 1,229,000	$ 1,186,000