Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 110,630	$ 100,008	$ 329,319	$ 305,790
Cost of sales	66,684	62,969	207,121	189,047
Gross margin	43,946	37,039	122,198	116,743
Selling, engineering and administration	28,212	24,724	80,139	74,023
Operating earnings	15,734	12,315	42,059	42,720
Interest expense, net	295	242	994	567
Other pension and postretirement costs (benefits)	11,787	(96)	19,799	249
Earnings before income taxes	3,652	12,169	21,266	41,904
Provision for income taxes	801	4,194	4,715	14,566
Net earnings	$ 2,851	$ 7,975	$ 16,551	$ 27,338
Earnings per share:
Basic (in dollars per share)	$ 0.10	$ 0.28	$ 0.57	$ 0.94
Diluted (in dollars per share)	0.10	0.27	0.57	0.94
Dividends declared per common share (in dollars per share)	$ 0.15	$ 0.13	$ 0.41	$ 0.36
Shares used in computation of earnings per share:
Basic (in shares)	28,989,205	28,939,292	28,983,115	28,939,940
Impact of dilutive securities (in shares)	207,955	178,756	198,428	173,468
Diluted (in shares)	29,197,160	29,118,048	29,181,543	29,113,408