Derivative Financial Instruments (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jul. 01, 2012 Agreement	Jul. 03, 2011 Agreement	Jul. 31, 2012	Jan. 01, 2012 Agreement
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains From Terminated Interest Rate Swap Amortised			$ 1.0
Derivative Financial Instruments (Textual) [Abstract]
Reduction in interest expense	0.6	0.6
Outstanding interest rate swap agreements	0	0		0
Percentage of aluminum purchase requirements hedged by using derivatives				75.00%
Gains From Terminated Interest Rate Swap Amortised			1.0
Five Month [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains From Terminated Interest Rate Swap Amortised			0.3
Derivative Financial Instruments (Textual) [Abstract]
Gains From Terminated Interest Rate Swap Amortised			0.3
Thirty Three Month [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains From Terminated Interest Rate Swap Amortised			0.7
Derivative Financial Instruments (Textual) [Abstract]
Gains From Terminated Interest Rate Swap Amortised			$ 0.7