Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 13,781	$ 11,854
Other comprehensive (loss) income:
Foreign currency translation adjustments	(714)	(627)
Pension and postretirement benefits, net of tax	3	1
Comprehensive income	$ 13,070	$ 11,228