Comprehensive Income (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Comprehensive Income [Abstract]
Net earnings	$ 18,451	$ 10,591	$ 30,851	$ 16,583
Other comprehensive income, before tax [Abstract]
Foreign currency translation adjustments	989	(3,856)	3,674	(4,957)
Defined benefit postretirement plans [Abstract]
Total other comprehensive income, before tax	(1,573)	2,447	2,209	2,748
Income tax benefit related to items of other comprehensive income	948	(2,332)	542	(2,851)
Total other comprehensive income (loss), net of tax	(625)	115	2,751	(103)
Total comprehensive income	17,826	10,706	33,602	16,480
Accumulated other comprehensive income (loss) [Abstract]
Foreign currency translation, beginning of period			5,077
Foreign currency translation, current-period change	989	(3,856)	3,674	(4,957)
Foreign currency translation, end of period	8,751		8,751
Defined benefit pension plans, beginning of period			(43,372)
Defined benefit pension plans, current-period change			(714)
Defined benefit pension plans, end of period	(44,086)		(44,086)
Defined benefit postretirement plans, beginning balance			1,649
Defined benefit postretirement plans, current-period change			(209)
Defined benefit postretirement plans, end of period	1,440		1,440
Accumulated other comprehensive loss, beginning of period			(36,646)
Accumulated other comprehensive loss, current-period change	(625)	115	2,751	(103)
Accumulated other comprehensive loss, end of period	(33,895)		(33,895)
Pension Benefits [Member]
Defined benefit pension plans [Abstract]
Amortization of prior service cost included in net periodic benefit cost	236	197	473	393
Amortization of unrecognized net loss included in net periodic benefit cost	1,049	628	1,958	1,856
Net (loss) gain arising during period	(3,565)	3,634	(3,565)	3,634
Total defined benefit plans	(2,280)	4,459	(1,134)	5,883
Other Postretirement Plans [Member]
Defined benefit postretirement plans [Abstract]
Amortization of prior service cost included in net periodic benefit cost	13	13	25	26
Amortization of unrecognized net gain included in net periodic benefit cost	(50)	(111)	(111)	(146)
Net (loss) gain arising during period	(245)	1,942	(245)	1,942
Total defined benefit postretirement plans	$ (282)	$ 1,844	$ (331)	$ 1,822