Retirement Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
U.S. Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	$ 165	$ 166
Interest cost	478	513
Expected return on plan assets	(571)	(580)
Amortization of net actuarial loss	286	26
Amortization of prior service cost	97	137
Foreign currency	0	0
Net periodic benefit cost	455	262
Non-U.S. Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	33	25
Interest cost	130	122
Expected return on plan assets	(117)	(108)
Amortization of net actuarial loss	0	0
Amortization of prior service cost	38	39
Foreign currency	(22)	61
Net periodic benefit cost	62	139
Postretirement Medical Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	35	33
Interest cost	140	162
Expected return on plan assets	0	0
Amortization of net actuarial loss	17	15
Amortization of prior service cost	(145)	(145)
Foreign currency	0	0
Net periodic benefit cost	47	65
Employer contributions to pension and postretirement medial benefit plans	134
Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Employer contributions to pension and postretirement medial benefit plans	$ 921