Comprehensive Income (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Comprehensive Income [Abstract]
Net earnings	$ 14,425	$ 12,637	$ 45,276	$ 29,219
Other comprehensive income, before tax [Abstract]
Foreign currency translation adjustments	(6,578)	4,029	(2,904)	(928)
Defined benefit postretirement plans [Abstract]
Total other comprehensive (loss) income, before tax	(5,406)	5,093	(3,198)	7,841
Income tax (expense) benefit related to items of other comprehensive income	(433)	(394)	109	(3,245)
Total other comprehensive (loss) income, net of tax	(5,839)	4,699	(3,089)	4,596
Total comprehensive income	8,586	17,336	42,187	33,815
Accumulated other comprehensive income (loss) [Abstract]
Foreign currency translation, beginning of period			5,077
Foreign currency translation, current-period change	(6,578)	4,029	(2,904)	(928)
Foreign currency translation, end of period	2,173		2,173
Defined benefit pension plans, beginning of period			(43,372)
Defined benefit pension plans, current-period change			51
Defined benefit pension plans, end of period	(43,321)		(43,321)
Defined benefit postretirement plans, beginning of period			1,649
Defined benefit postretirement plans, current-period change			(236)
Defined benefit postretirement plans, end of period	1,413		1,413
Accumulated other comprehensive loss, beginning of period			(36,646)
Accumulated other comprehensive loss, current-period change	(5,839)	4,699	(3,089)	4,596
Accumulated other comprehensive loss, end of period	(39,735)		(39,735)
Pension Benefits [Member]
Defined benefit pension plans [Abstract]
Amortization of prior service cost included in net periodic benefit cost	236	196	709	589
Amortization of unrecognized net loss included in net periodic benefit cost	979	928	2,936	2,784
Net (loss) gain arising during period - defined benefit plan	0	0	(3,565)	3,634
Total defined benefit pension plans	1,215	1,124	80	7,007
Other Postretirement Plans [Member]
Defined benefit postretirement plans [Abstract]
Amortization of prior service cost included in net periodic benefit cost	13	13	38	38
Amortization of unrecognized net gain included in net periodic benefit cost	(56)	(73)	(167)	(218)
Net (loss) gain arising during period - postretirement benefit	0	0	(245)	1,942
Total defined benefit postretirement plans	$ (43)	$ (60)	$ (374)	$ 1,762