Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 47,177	$ 27,790	$ 34,571
Other comprehensive income :
Foreign currency translation adjustment	(58)	(484)	1,844
Pension and postretirement benefits, net of tax	(97)	13,657	(1,102)
Comprehensive income	$ 47,022	$ 40,963	$ 35,313