Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net earnings	$ 18,783	$ 19,346
Other comprehensive (loss) income, net of tax:
Net foreign currency translation adjustment	(1,089)	1,363
Net change in postretirement benefit plans, net of taxes of $(2) and $(4) for the three months ended March 31, 2019 and 2018	5	13
Other comprehensive (loss) income	(1,084)	1,376
Comprehensive income	$ 17,699	$ 20,722