Retirement Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
U.S. Pension Benefits
Components of the net periodic benefit cost
Service cost	$ 85	$ 175	$ 517	$ 514
Interest cost	221	485	1,352	1,446
Expected return on plan assets	(363)	(569)	(2,183)	(1,709)
Amortization of net actuarial loss	217	281	1,313	849
Amortization of prior service cost	9	94	55	286
Foreign currency	0	0	0	0
Net periodic benefit cost	169	466	1,054	1,386
Non-U.S. Pension Benefits
Components of the net periodic benefit cost
Service cost	34	33	100	99
Interest cost	122	131	365	392
Expected return on plan assets	(116)	(118)	(347)	(353)
Amortization of net actuarial loss	0	0	0	0
Amortization of prior service cost	(353)	38	(192)	115
Foreign currency	(56)	(10)	(27)	13
Net periodic benefit cost	(369)	74	(101)	266
Postretirement Medical Benefits
Components of the net periodic benefit cost
Service cost	39	34	115	104
Interest cost	110	140	332	419
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	49	17	150	51
Amortization of prior service cost	(25)	(145)	(77)	(435)
Foreign currency	0	0	0	0
Net periodic benefit cost	173	46	520	139
Employer contributions to pension and postretirement medial benefit plans	128		357
Pension Benefits
Components of the net periodic benefit cost
Employer contributions to pension and postretirement medial benefit plans	$ 70		$ 207