Quarterly Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 29, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Oct. 01, 2011		Jun. 30, 2011		Apr. 02, 2011		Dec. 29, 2012		Dec. 31, 2011		Jan. 01, 2011
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 291,612		$ 257,699		$ 260,040		$ 228,823		$ 243,760		$ 218,720		$ 210,855		$ 182,572		$ 1,038,174		$ 855,907		$ 719,121
Gross Profit	113,245		100,445		101,816		87,483		99,652		87,318		85,337		71,830		402,989		344,137		286,677
Income from operations	58,657		47,429		45,338		36,660		44,912		37,186		35,248		31,364		188,084	[1]	148,710	[1]	122,788	[1]
Net earnings	$ 37,788		$ 29,769		$ 31,045		$ 22,095		$ 34,559		$ 23,461		$ 19,628		$ 17,825		$ 120,697		$ 95,473		$ 72,867
Basic earnings per share (usd per share)	$ 2.06	[2]	$ 1.63	[2]	$ 1.70	[2]	$ 1.22	[2]	$ 1.92	[2]	$ 1.30	[2]	$ 1.09	[2]	$ 1.00	[2]	$ 6.61	[2]	$ 5.30	[2]	$ 4.09
Diluted earnings per share (usd per share)	$ 2.03	[2]	$ 1.60	[2]	$ 1.67	[2]	$ 1.20	[2]	$ 1.87	[2]	$ 1.26	[2]	$ 1.06	[2]	$ 0.97	[2]	$ 6.49	[2]	$ 5.15	[2]	$ 3.97

[1] Non-operating expenses are not allocated to the reportable segments. Non-operating expenses consist of interest expense and deferred financing amortization, foreign exchange gains and losses and other income and expense items outside of income from operations.

[2] Sum of quarters may not equal the total for the year due to changes in the number of shares outstanding during the year.