Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Net sales	$ 99,388	$ 96,271	$ 281,928	$ 275,429
Cost of sales	63,287	59,806	180,609	175,182
Gross margin	36,101	36,465	101,319	100,247
Selling, engineering and administration	22,477	20,482	68,460	62,353
Operating earnings	13,624	15,983	32,859	37,894
Interest expense, net	305	273	941	875
Earnings before income taxes	13,319	15,710	31,918	37,019
Provision for income taxes	4,992	5,479	11,463	13,342
Net earnings	$ 8,327	$ 10,231	$ 20,455	$ 23,677
Earnings per share:
Basic (in dollars per share)	$ 0.58	$ 0.71	$ 1.42	$ 1.67
Diluted (in dollars per share)	0.58	0.71	1.42	1.66
Dividends declared per common share (in dollars per share)	$ 0.20	$ 0.19	$ 0.58	$ 0.55
Shares used in computation of earnings per share:
Basic (in shares)	14,392,517	14,312,847	14,373,470	14,177,483
Impact of dilutive securities (in shares)	64,104	64,108	67,695	70,643
Diluted (in shares)	14,456,621	14,376,955	14,441,165	14,248,126