Condensed Consolidated Statements of Comprehensive Income (unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Condensed Consolidated Statements of Comprehensive Income (unaudited) [Abstract]
Net earnings	$ 15,178	$ 11,657	$ 33,804	$ 34,127
Other comprehensive (loss) income, net of tax:
Net foreign currency translation adjustment	(1,739)	749	(1,934)	484
Net change in postretirement benefit plan, net of taxes of $1 and $-0- for the three months ended September 30, 2014 and 2013, and $3 and $1 for the nine months ended September 30, 2014 and 2013	(2)	1	(6)	(1)
Other comprehensive (loss) income	(1,741)	750	(1,940)	483
Comprehensive income	$ 13,437	$ 12,407	$ 31,864	$ 34,610