Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Income Statement [Abstract]
Net sales	$ 284,673	$ 276,878	$ 678,572	$ 629,858
Cost of sales	108,054	105,617	255,494	249,523
Gross profit	176,619	171,261	423,078	380,335
Operating expenses:
Sales and marketing	144,498	134,785	313,764	285,453
General and administrative	28,819	27,018	62,588	57,924
Research and development	6,363	7,062	13,959	14,664
Total operating expenses	179,680	168,865	390,311	358,041
Operating (loss) income	(3,061)	2,396	32,767	22,294
Other expense, net	(282)	(229)	(420)	(326)
(Loss) income before income taxes	(3,343)	2,167	32,347	21,968
Income tax (benefit) expense	(2,565)	751	8,664	7,583
Net (loss) income	$ (778)	$ 1,416	$ 23,683	$ 14,385
Basic net (loss) income per share:
Net (loss) income per share – basic	$ (0.02)	$ 0.03	$ 0.56	$ 0.30
Weighted-average shares – basic	41,716,000	46,394,000	42,233,000	47,247,000
Diluted net (loss) income per share:
Net (loss) income per share – diluted	$ (0.02)	$ 0.03	$ 0.55	$ 0.30
Weighted-average shares – diluted	41,716,000	47,044,000	43,080,000	47,945,000