Retirement Benefit Plans (Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial (gain) loss	$ 1,397	$ (1,343)
Amortization of actuarial loss	(484)	(363)
Amortization of prior service credit	(58)	(58)
Settlements	0	(76)
Total recognized in other comprehensive loss (income)	855	(1,840)
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial (gain) loss	(756)	154
Amortization of actuarial loss	(96)	(97)
Current year prior service credit	(325)	0
Amortization of prior service credit	64	17
Total recognized in other comprehensive loss (income)	$ (1,113)	$ 74