Retirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	$ 105
U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	80	$ 106
Interest cost	415	432
Expected return on plan assets	(597)	(652)
Amortization of net actuarial loss	9	226
Amortization of prior service cost	11	11
Foreign currency	0	0
Net periodic (benefit) cost	(82)	123
Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	36	36
Interest cost	105	123
Expected return on plan assets	(97)	(144)
Amortization of net actuarial loss	0	0
Amortization of prior service cost	32	65
Foreign currency	40	(83)
Net periodic (benefit) cost	116	(3)
Postretirement Medical Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	279
Service cost	24	31
Interest cost	99	109
Expected return on plan assets	0	0
Amortization of net actuarial loss	0	0
Amortization of prior service cost	0	35
Foreign currency	0	0
Net periodic (benefit) cost	$ 123	$ 175