Derivative financial instruments and fair value measurements (Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis ) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended				9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended							9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended							9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended							9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013 Fair Value, Inputs, Level 1 [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 1 [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member] Interest Rate Swap [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 1 [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member] Foreign Exchange Forward [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 1 [Member] Other Current [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member] Other Current [Member] Future And Forward Contracts [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 1 [Member] Other Long Term [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member] Other Long Term [Member] Future And Forward Contracts [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 2 [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 2 [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member] Interest Rate Swap [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 2 [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member] Foreign Exchange Forward [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 2 [Member] Other Current [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member] Other Current [Member] Future And Forward Contracts [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 2 [Member] Other Long Term [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member] Other Long Term [Member] Future And Forward Contracts [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 3 [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 3 [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member] Interest Rate Swap [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 3 [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member] Foreign Exchange Forward [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 3 [Member] Other Current [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member] Other Current [Member] Future And Forward Contracts [Member]	Sep. 28, 2013 Fair Value, Inputs, Level 3 [Member] Other Long Term [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member] Other Long Term [Member] Future And Forward Contracts [Member]	Sep. 28, 2013 Fair Value, Measurements, Recurring [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member]	Sep. 28, 2013 Fair Value, Measurements, Recurring [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member] Interest Rate Swap [Member]	Sep. 28, 2013 Fair Value, Measurements, Recurring [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member] Foreign Exchange Forward [Member]	Sep. 28, 2013 Fair Value, Measurements, Recurring [Member] Other Current [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member] Other Current [Member] Future And Forward Contracts [Member]	Sep. 28, 2013 Fair Value, Measurements, Recurring [Member] Other Long Term [Member] Future And Forward Contracts [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member] Other Long Term [Member] Future And Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Derivative Gain											$ 270	$ 690	$ 0	$ 0							$ 1,807	$ 2,494	$ 12	$ 93							$ 0	$ 0	$ 0	$ 0							$ 2,077	$ 3,184	$ 12	$ 93
Unrealized Derivative Loss											0	0	0	0							(3,209)	(1,623)	(161)	(43)							0	0	0	0							(3,209)	(1,623)	(161)	(43)
Inventories Carried At Market						0					0					15,426					11,521					0					0					15,426					11,521
Unrealized Gain (Loss) on Derivatives	1,950	(3,075)	2,892	(1,178)			0	0	0	0							(188)	(396)	(365)	(327)							0	0	0	0							(188)	(396)	(365)	(327)
Business Acquisition, Contingent Consideration, at Fair Value					$ 0	$ 0									$ 0	$ 0									$ 3,161	$ 4,398									$ 3,161	$ 4,398