Retirement Benefit Plans (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4	$ 4
Interest cost	757	831
Expected return on plan assets	(1,454)	(1,275)
Amortization of net loss	346	433
Net periodic benefit cost	(347)	(7)
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	249	198
Interest cost	248	204
Amortization of prior service cost	501	406
Net periodic benefit cost	$ 998	$ 808