Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 433,732	$ 402,440	$ 393,761
Cost of sales	271,383	246,694	243,185
Gross margin	162,349	155,746	150,576
Selling, engineering and administration	105,480	99,151	97,904
Operating earnings	56,869	56,595	52,672
Interest expense, net	1,157	789	921
Other pension and postretirement costs	19,860	973	1,907
Earnings before income taxes	35,852	54,833	49,844
Provision for income taxes	8,062	20,262	17,549
Net earnings	$ 27,790	$ 34,571	$ 32,295
Earnings per share:
Basic	$ 0.96	$ 1.20	$ 1.12
Diluted	$ 0.95	$ 1.19	$ 1.11
Shares used in computation of earnings per share:
Basic	28,993	28,927	28,887
Impact of dilutive securities	196	184	163
Diluted	29,189	29,111	29,050