Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014
Income Statement [Abstract]
Net sales	$ 275,289	$ 234,763	$ 625,098	$ 511,175
Cost of sales	104,750	92,366	238,726	197,395
Gross profit	170,539	142,397	386,372	313,780
Operating expenses:
Sales and marketing	126,627	106,712	267,130	231,734
General and administrative	23,880	21,265	52,134	40,161
Research and development	3,403	1,709	6,754	3,372
Total operating expenses	153,910	129,686	326,018	275,267
Operating income	16,629	12,711	60,354	38,513
Other income, net	133	78	286	180
Income before income taxes	16,762	12,789	60,640	38,693
Income tax expense	5,724	4,308	20,803	13,220
Net income	$ 11,038	$ 8,481	$ 39,837	$ 25,473
Basic net income per share:
Net income per share – basic (in USD per share)	$ 0.21	$ 0.16	$ 0.77	$ 0.47
Weighted-average shares – basic (in shares)	51,672,000	53,648,000	52,009,000	53,880,000
Diluted net income per share:
Net income per share – diluted (in USD per share)	$ 0.21	$ 0.16	$ 0.75	$ 0.47
Weighted-average shares – diluted (in shares)	52,544,000	54,324,000	52,935,000	54,570,000