Retirement Benefit Plans (Summary of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligations	$ 4,663	$ 6,511	$ 7,941
Expected return on plan assets	(14,385)	(13,522)	(11,436)
Recognized net loss	4,102	4,027	5,705
Net periodic benefit cost (benefit)	(5,620)	(2,984)	2,210
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligations	30	46	65
Expected return on plan assets	0	0	0
Recognized net loss	38	23	14
Net periodic benefit cost (benefit)	68	69	79
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost on benefit obligations	19	46	85
Expected return on plan assets	0	0	0
Recognized net loss	(38)	(74)	(13)
Net periodic benefit cost (benefit)	$ (19)	$ (28)	$ 72