Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 426,445	$ 388,633
Cost of sales	164,212	151,156
Gross profit	262,233	237,477
Operating expenses:
Sales and marketing	186,827	171,917
General and administrative	34,323	31,734
Research and development	8,376	6,925
Total operating expenses	229,526	210,576
Operating income	32,707	26,901
Other expense, net	2,609	525
Income before income taxes	30,098	26,376
Income tax expense	4,680	5,828
Net income	$ 25,418	$ 20,548
Basic net income per share:
Net income per share – basic	$ 0.83	$ 0.54
Weighted-average shares – basic	30,620,000	38,244,000
Diluted net income per share:
Net income per share – diluted	$ 0.80	$ 0.52
Weighted-average shares – diluted	31,738,000	39,347,000