Quarterly Financial Results (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 03, 2015	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Jan. 03, 2015	Dec. 28, 2013	Dec. 29, 2012
Quarterly Financial Results [Abstract]
Net sales	$ 227,870	$ 191,944	$ 188,256	$ 182,401	$ 186,266	$ 173,691	$ 189,136	$ 169,082	$ 790,471	$ 718,175	$ 648,726
Gross profit	190,354	157,359	153,391	148,573	152,488	142,200	157,231	138,821	649,677	590,740	532,922
Net earnings	$ 21,300	$ 19,498	$ 19,301	$ 16,537	$ 20,282	$ 16,753	$ 24,210	$ 17,779	$ 76,636	$ 79,024	$ 66,433
Basic	$ 1.72	$ 1.51	$ 1.40	$ 1.19	$ 1.46	$ 1.22	$ 1.79	$ 1.30	$ 5.80	$ 5.77	$ 4.57
Diluted	$ 1.65	$ 1.47	$ 1.36	$ 1.15	$ 1.41	$ 1.16	$ 1.72	$ 1.28	$ 5.60	$ 5.56	$ 4.45