Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Income Statement [Abstract]
Net sales	$ 238,147	$ 229,262	$ 465,409	$ 450,887
Cost of goods sold	145,446	138,410	284,072	271,292
Gross profit	92,701	90,852	181,337	179,595
Selling, general and administrative expenses	49,921	45,853	98,563	89,554
Income from operations	42,780	44,999	82,774	90,041
Other income, net	73	241	224	305
Income before income taxes	42,853	45,240	82,998	90,346
Provision for income taxes	8,514	16,803	18,013	32,722
Net income	$ 34,339	$ 28,437	$ 64,985	$ 57,624
Earnings Per Share:
Basic	$ 1.04	$ 0.83	$ 1.95	$ 1.68
Diluted	$ 1.03	$ 0.83	$ 1.95	$ 1.68
Weighted Average Shares Outstanding:
Basic	33,146	34,128	33,273	34,256
Diluted	33,226	34,225	33,355	34,350