Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Net sales	$ 103,820	$ 98,896	$ 204,390	$ 182,540
Cost of sales	64,424	63,753	125,983	117,322
Gross margin	39,396	35,143	78,407	65,218
Selling, engineering and administration	24,474	22,961	50,679	45,983
Operating earnings	14,922	12,182	27,728	19,235
Interest expense, net	228	319	498	636
Earnings before income taxes	14,694	11,863	27,230	18,599
Provision for income taxes	5,294	3,962	9,840	6,471
Net earnings	$ 9,400	$ 7,901	$ 17,390	$ 12,128
Earnings per share:
Basic (in dollars per share)	$ 0.65	$ 0.55	$ 1.20	$ 0.84
Diluted (in dollars per share)	0.65	0.55	1.20	0.84
Dividends declared per common share (in dollars per share)	$ 0.20	$ 0.19	$ 0.40	$ 0.38
Shares used in computation of earnings per share:
Basic (in shares)	14,443,539	14,379,450	14,434,397	14,361,464
Impact of dilutive securities (in shares)	82,166	63,816	79,799	73,096
Diluted (in shares)	14,525,705	14,443,266	14,514,196	14,434,560