Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Income Statement [Abstract]
Net sales	$ 323,366	$ 263,689	$ 834,541	$ 729,317
Cost of sales	124,782	97,269	322,177	268,083
Gross profit	198,584	166,420	512,364	461,234
Operating expenses:
Sales and marketing	137,863	118,307	369,597	326,477
General and administrative	23,022	15,055	63,183	46,249
Research and development	2,353	2,359	5,725	7,475
Total operating expenses	163,238	135,721	438,505	380,201
Operating income	35,346	30,699	73,859	81,033
Other income, net	96	74	276	243
Income before income taxes	35,442	30,773	74,135	81,276
Income tax expense	11,888	10,514	25,108	27,620
Net income	$ 23,554	$ 20,259	$ 49,027	$ 53,656
Basic net income per share:
Net income per share – basic (in USD per share)	$ 0.44	$ 0.37	$ 0.91	$ 0.98
Weighted-average shares – basic (in shares)	53,271	54,854	53,677	54,992
Diluted net income per share:
Net income per share – diluted (in USD per share)	$ 0.44	$ 0.36	$ 0.90	$ 0.96
Weighted-average shares – diluted (in shares)	53,971	55,748	54,358	55,990