Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales	$ 105,041	$ 101,606
Cost of sales	68,293	62,956
Gross margin	36,748	38,650
Selling, engineering and administration	26,774	25,085
Operating earnings	9,974	13,565
Interest expense, net	290	178
Other pension and postretirement benefits (costs)	(19)	96
Earnings before income taxes	9,703	13,291
Provision for income taxes	2,157	4,542
Net earnings	$ 7,546	$ 8,749
Earnings per share:
Basic (in dollars per share)	$ 0.26	$ 0.30
Diluted (in dollars per share)	0.26	0.30
Dividends declared per common share (in dollars per share)	$ 0.130	$ 0.115
Shares used in computation of earnings per share:
Basic (in shares)	28,932,787	28,900,702
Impact of dilutive securities (in shares)	217,259	182,279
Diluted (in shares)	29,150,046	29,082,981