Commitments, contingencies and other (Narrative) (Details)	3 Months Ended			0 Months Ended	3 Months Ended			1 Months Ended	0 Months Ended
	Mar. 30, 2013 USD ($)	Mar. 30, 2013 Cost of Sales [Member] USD ($)	Mar. 30, 2013 Selling, General and Administrative [Member] USD ($)	Jan. 30, 2013 BELGIUM Foreign Tax Authority [Member] USD ($)	Mar. 31, 2012 BELGIUM Foreign Tax Authority [Member] EUR (€)	Jan. 30, 2013 BELGIUM Foreign Tax Authority [Member] EUR (€)	Dec. 28, 2012 BELGIUM Foreign Tax Authority [Member] EUR (€)	Jan. 31, 2012 BELGIUM Foreign Tax Authority [Member] Two Thousand and Eight [Member] EUR (€)	Dec. 28, 2012 BELGIUM Foreign Tax Authority [Member] Two Thousand and Five [Member] EUR (€)	Dec. 28, 2012 BELGIUM Foreign Tax Authority [Member] Two Thousand and Nine [Member] EUR (€)
Commitments And Contingencies [Line Items]
Assessment received from Belgian tax authority (in euros)								€ 23,789,000	€ 46,135,000	€ 35,567,000
Interest on assessment (in euros)					2,912,000
Refund of interest deposit						2,912,000	23,789,000
Interest Tax Examination, Refund, Interest Income				2,000,000
Pre-tax business restructuring charges	$ 8,222,000	$ 3,006,000	$ 5,216,000