Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net earnings	$ 21,568	$ 20,676	$ 62,461	$ 59,288
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	4,313	(2,209)	7,440	(3,513)
Unrealized gain (loss) on cash flow hedge	227	(657)	(2,659)	(1,956)
Change in postretirement benefit plans	137	5	(434)	16
Other comprehensive gain (loss)	4,677	(2,861)	4,347	(5,453)
Comprehensive income	$ 26,245	$ 17,815	$ 66,808	$ 53,835