Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net earnings	$ 49,826	$ 58,854	$ 60,438
Other comprehensive income, net of tax:
Foreign currency translation adjustments	27,840	(12,271)	(1,949)
Change in unrealized loss on derivative instruments, net of tax expense of $31, $6, and $158, respectively	51	9	263
Pension plan adjustments, net of tax expense (benefit) of $7,661, ($2,412), and ($7,382), respectively	12,688	(3,993)	(12,191)
Other comprehensive income (loss)	40,579	(16,255)	(13,877)
Total comprehensive income	$ 90,405	$ 42,599	$ 46,561