Retirement Benefit Plans (Obligation and Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
U.S. Plan
Change in benefit obligation
Projected benefit obligation at beginning of year	$ 19,131	$ 21,716
Interest cost	727	681	$ 811
Actuarial (gain) loss	1,266	(1,278)
Benefits paid	(1,750)	(1,988)
Foreign currency exchange rate changes	0	0
Projected benefit obligation at end of year	19,374	19,131	21,716
Accumulated benefit obligation at end of year	19,374	19,131
Change in plan assets
Fair value of plan assets at beginning of year	25,671	29,237
Actual return on plan assets	4,979	(1,578)
Benefits paid	(1,750)	(1,988)
Foreign currency exchange rate changes	0	0
Fair value of plan assets at end of year	28,900	25,671	29,237
Funded status at end of year	9,526	6,540
Amounts recognized in the balance sheets consist of:
Non-current assets	9,526	6,540
Components of accumulated other comprehensive loss consist of:
Actuarial loss	(9,140)	(11,427)
Deferred taxes and other	2,280	2,933
Accumulated other comprehensive (loss) income	(6,860)	(8,494)
Non-U.S. Plan
Change in benefit obligation
Projected benefit obligation at beginning of year	4,084	4,604
Interest cost	144	142	153
Actuarial (gain) loss	311	(148)
Benefits paid	(182)	(151)
Foreign currency exchange rate changes	213	(363)
Projected benefit obligation at end of year	4,570	4,084	4,604
Accumulated benefit obligation at end of year	4,570	4,084
Change in plan assets
Fair value of plan assets at beginning of year	4,744	5,456
Actual return on plan assets	726	(111)
Benefits paid	(182)	(151)
Foreign currency exchange rate changes	62	(450)
Fair value of plan assets at end of year	5,350	4,744	$ 5,456
Funded status at end of year	780	660
Amounts recognized in the balance sheets consist of:
Non-current assets	780	660
Components of accumulated other comprehensive loss consist of:
Actuarial loss	(1,058)	(1,225)
Deferred taxes and other	348	485
Accumulated other comprehensive (loss) income	$ (710)	$ (740)