Retirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	$ 102		$ 311
U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	88	$ 120	265	$ 360
Interest cost	414	428	1,244	1,283
Expected return on plan assets	(599)	(653)	(1,799)	(1,960)
Amortization of net actuarial loss	13	209	30	627
Amortization of prior service cost	10	10	31	31
Foreign currency	0	0	0	0
Net periodic (benefit) cost	(74)	114	(229)	341
Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	32	36	104	108
Interest cost	96	125	304	373
Expected return on plan assets	(89)	(148)	(283)	(438)
Amortization of net actuarial loss	0	0	0	0
Amortization of prior service cost	29	67	93	197
Foreign currency	(57)	8	(33)	43
Net periodic (benefit) cost	11	88	185	283
Postretirement Medical Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	381		845
Service cost	25	24	73	72
Interest cost	99	98	298	294
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	0	0	0	0
Amortization of prior service cost	0	0	0	0
Foreign currency	0	0	0	0
Net periodic (benefit) cost	$ 124	$ 122	$ 371	$ 366