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, 2019	Dec. 31, 2018	Dec. 31, 2017
U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial loss	$ (1,727)	$ 2,347	$ (2,506)
Amortization of actuarial loss	(561)	(623)	(501)
Total recognized in other comprehensive loss	(2,288)	1,724	(3,007)
Non-U.S. Plan
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial loss	(155)	236	60
Amortization of actuarial loss	(72)	(200)	(10)
Total recognized in other comprehensive loss	$ (227)	$ 36	$ 50