Consolidated Condensed Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 12,721	$ 2,851	$ 34,903	$ 16,551
Other comprehensive income:
Foreign currency translation adjustments	(646)	106	(509)	(281)
Pension and postretirement benefits, net of tax	(16)	7,396	333	13,168
Comprehensive income	$ 12,059	$ 10,353	$ 34,727	$ 29,438