Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 13,972	$ 9,534	$ 27,753	$ 21,388
Other comprehensive income:
Foreign currency translation adjustments	2,806	445	2,093	(182)
Pension and postretirement benefits, net of tax	3	1	5	2
Comprehensive income	$ 16,781	$ 9,980	$ 29,851	$ 21,208