Retirement Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
U.S. Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	$ 175	$ 163	$ 514	$ 489
Interest cost	485	503	1,446	1,509
Expected return on plan assets	(569)	(581)	(1,709)	(1,744)
Amortization of net actuarial loss (gain)	281	7	849	21
Amortization of prior service cost	94	137	286	412
Foreign currency	0	0	0	0
Net periodic benefit cost	466	229	1,386	687
Non-U.S. Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	33	25	99	75
Interest cost	131	122	392	366
Expected return on plan assets	(118)	(109)	(353)	(325)
Amortization of net actuarial loss (gain)	0	0	0	0
Amortization of prior service cost	38	40	115	118
Foreign currency	(10)	(325)	13	(248)
Net periodic benefit cost	74	(247)	266	(14)
Postretirement Medical Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	34	33	104	99
Interest cost	140	153	419	459
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss (gain)	17	0	51	0
Amortization of prior service cost	(145)	(145)	(435)	(435)
Foreign currency	0	0	0	0
Net periodic benefit cost	46	41	139	123
Employer contributions to pension and postretirement medial benefit plans	186		425
Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Employer contributions to pension and postretirement medial benefit plans	$ 517		$ 1,512