Retirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	$ 77		$ 279
U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	120	$ 123	360	$ 370
Interest cost	428	491	1,283	1,473
Expected return on plan assets	(653)	(670)	(1,960)	(2,012)
Amortization of net actuarial loss	209	37	627	111
Amortization of prior service cost (benefit)	10	11	31	32
Foreign currency	0	0	0	0
Net periodic cost (benefit)	114	(8)	341	(26)
Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	36	38	108	114
Interest cost	125	133	373	399
Expected return on plan assets	(148)	(131)	(438)	(391)
Amortization of net actuarial loss	0	0	0	0
Amortization of prior service cost (benefit)	67	46	197	139
Foreign currency	8	98	43	114
Net periodic cost (benefit)	88	184	283	375
Postretirement Medical Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	236		820
Service cost	24	32	72	96
Interest cost	98	124	294	373
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	0	(2)	0	0
Amortization of prior service cost (benefit)	0	0	0	(5)
Foreign currency	0	0	0	0
Net periodic cost (benefit)	$ 122	$ 154	$ 366	$ 464