Retirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans
Foreign currency				$ 0
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	$ 76		$ 202
U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	134	$ 123	240	247
Interest cost	423	488	855	982
Expected return on plan assets	(655)	(672)	(1,307)	(1,342)
Amortization of net actuarial loss	192	30	418	74
Amortization of prior service cost (benefit)	10	10	21	21
Foreign currency	0	0	0	0
Net periodic cost (benefit)	104	(21)	227	(18)
Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	36	38	72	76
Interest cost	125	134	248	266
Expected return on plan assets	(146)	(131)	(290)	(260)
Amortization of net actuarial loss	0	0	0	0
Amortization of prior service cost (benefit)	65	47	130	93
Foreign currency	118	(2)	35	16
Net periodic cost (benefit)	198	86	195	191
Postretirement Medical Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Plan contributions	204		584
Service cost	17	32	48	64
Interest cost	87	118	196	249
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	(35)	(11)	0	0
Amortization of prior service cost (benefit)	0	(1)	0	(3)
Foreign currency	0	0	0
Net periodic cost (benefit)	$ 69	$ 138	$ 244	$ 310