Condensed Consolidated Statements of Net Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Net sales	$ 317,889	$ 280,331	$ 916,685	$ 771,641
Cost of sales	184,238	166,572	536,776	472,861
Gross profit	133,651	113,759	379,909	298,780
Selling, general, and administrative expenses	56,759	56,589	156,899	150,047
Research and development expenses	11,991	10,403	36,872	30,884
Amortization of intangibles	6,292	4,432	18,407	13,384
Impairment of goodwill and intangible assets		14,809		14,809
Total operating expenses	75,042	86,233	212,178	209,124
Operating income	58,609	27,526	167,731	89,656
Interest expense	3,467	2,571	9,868	6,286
Foreign exchange loss (gain)	632	(4,700)	(1,483)	(7,114)
Other income, net	(1,013)	(778)	(962)	(1,040)
Income before income taxes	55,523	30,433	160,308	91,524
Income taxes	12,715	(369)	29,970	14,281
Net income	$ 42,808	$ 30,802	$ 130,338	$ 77,243
Income per share:
Basic (in dollars per share)	$ 1.88	$ 1.36	$ 5.75	$ 3.43
Diluted (in dollars per share)	$ 1.87	$ 1.35	$ 5.69	$ 3.41
Weighted-average shares outstanding:
Basic (in shares)	22,713	22,578	22,678	22,515
Diluted (in shares)	22,953	22,734	22,906	22,675