Retirement Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
U.S. Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	$ 174	$ 160	$ 339	$ 326
Interest cost	483	493	961	1,006
Expected return on plan assets	569	583	1,140	1,163
Amortization of net actuarial loss (gain)	282	(12)	568	14
Amortization of prior service cost	95	138	192	275
Foreign currency	0	0	0	0
Net periodic benefit cost	465	196	920	458
Non-U.S. Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	33	25	66	50
Interest cost	131	122	261	244
Expected return on plan assets	118	108	235	216
Amortization of net actuarial loss (gain)	0	0	0	0
Amortization of prior service cost	39	39	77	78
Foreign currency	45	16	23	77
Net periodic benefit cost	130	94	192	233
Postretirement Medical Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	35	33	70	66
Interest cost	139	144	279	306
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss (gain)	17	(15)	34	0
Amortization of prior service cost	(145)	(145)	(290)	(290)
Foreign currency	0	0	0	0
Net periodic benefit cost	46	17	93	82
Employer contributions to pension and postretirement medial benefit plans	105		239
Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Employer contributions to pension and postretirement medial benefit plans	$ 74		$ 995