Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Net sales	$ 794,059	$ 752,148	$ 705,322
Cost of sales	435,140	410,118	391,791
Gross profit	358,919	342,030	313,531
Operating expenses:
Research and development and other engineering	46,196	39,018	36,843
Selling	90,663	92,031	85,102
General and administrative	113,428	111,500	108,070
Impairment of goodwill	0	530	0
Net loss (gain) on disposal of assets	(389)	(325)	2,038
Total operating expenses	249,898	242,754	232,053
Income from operations	109,021	99,276	81,478
Interest income	655	901	987
Interest expense	(997)	(855)	(901)
Income before taxes	108,679	99,322	81,564
Provision for income taxes	40,791	35,791	30,593
Net income	$ 67,888	$ 63,531	$ 50,971
Earnings per common share:
Basic (in USD per share)	$ 1.39	$ 1.30	$ 1.05
Diluted (in USD per share)	$ 1.38	$ 1.29	$ 1.05
Weighted average number of shares outstanding
Basic (in shares)	48,952	48,977	48,521
Diluted (in shares)	49,181	49,194	48,673