Inventories (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 30, 2013	Mar. 31, 2012	Dec. 31, 2011	Dec. 29, 2012
Inventories [Abstract]
Raw materials and supplies	$ 28,957,000			$ 46,114,000
Work-in-process	39,184,000			40,951,000
Finished goods	167,334,000			148,014,000
Valuation reserves	(7,264,000)			(5,645,000)
Inventories	228,211,000			229,434,000
Possible effect of liquidation of LIFO layers on cost of goods sold	19,800,000
Pre-tax provision for lower-of-cost-or-market	1,400,000
Inventory write down, per diluted share (in dollars per share)	$ 0.03
Deferred LIFO Gain			8,000,000
Effect of liquidation of LIFO layers on cost of sales		$ 8,000,000
Effect of liquidation of LIFO layers per diluted share after tax (in dollars per share)		$ 0.13