Retirement Plans (Components of Net Periodic Benefits Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,929	$ 2,926	$ 5,729	$ 6,376
Interest cost	3,708	2,970	7,125	6,430
Expected return on plan assets	(11,711)	(11,333)	(23,186)	(23,391)
Amortization of net (gain) or loss and prior service costs	582	1,654	1,930	3,754
Special termination benefits		16,052		16,052
Net periodic benefit cost	(4,492)	(12,269)	(8,402)	9,221
Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	25	21	50	48
Interest cost	76	67	153	166
Amortization of net (gain) or loss and prior service costs	(139)	(163)	(278)	(309)
Special termination benefits		4,137		4,137
Net periodic benefit cost	$ (38)	$ (4,062)	$ (75)	$ 4,042