Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net earnings	$ 21,125	$ 19,829	$ 40,893	$ 38,612
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	2,346	(215)	3,127	(1,304)
Unrealized gain (loss) on cash flow hedge	221	(1,299)	(2,886)	(1,299)
Change in postretirement benefit plans	8	6	(571)	11
Other comprehensive gain (loss)	2,575	(1,508)	(330)	(2,592)
Comprehensive income	$ 23,700	$ 18,321	$ 40,563	$ 36,020