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		6 Months Ended				6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended							6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended							6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended							6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013 Fair Value, Inputs, Level 1 [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member]	Jun. 29, 2013 Fair Value, Inputs, Level 1 [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member] Interest Rate Swap [Member]	Jun. 29, 2013 Fair Value, Inputs, Level 1 [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 1 [Member] Foreign Exchange Forward [Member]	Jun. 29, 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]	Jun. 29, 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]	Jun. 29, 2013 Fair Value, Inputs, Level 2 [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member]	Jun. 29, 2013 Fair Value, Inputs, Level 2 [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member] Interest Rate Swap [Member]	Jun. 29, 2013 Fair Value, Inputs, Level 2 [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 2 [Member] Foreign Exchange Forward [Member]	Jun. 29, 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]	Jun. 29, 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]	Jun. 29, 2013 Fair Value, Inputs, Level 3 [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member]	Jun. 29, 2013 Fair Value, Inputs, Level 3 [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member] Interest Rate Swap [Member]	Jun. 29, 2013 Fair Value, Inputs, Level 3 [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Inputs, Level 3 [Member] Foreign Exchange Forward [Member]	Jun. 29, 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]	Jun. 29, 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]	Jun. 29, 2013 Fair Value, Measurements, Recurring [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member]	Jun. 29, 2013 Fair Value, Measurements, Recurring [Member] Interest Rate Swap [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member] Interest Rate Swap [Member]	Jun. 29, 2013 Fair Value, Measurements, Recurring [Member] Foreign Exchange Forward [Member]	Dec. 29, 2012 Fair Value, Measurements, Recurring [Member] Foreign Exchange Forward [Member]	Jun. 29, 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]	Jun. 29, 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											$ 339	$ 690	$ 0	$ 0							$ 3,179	$ 2,494	$ 276	$ 93							$ 0	$ 0	$ 0	$ 0							$ 3,518	$ 3,184	$ 276	$ 93
Unrealized Derivative Loss											0	0	0	0							(2,962)	(1,623)	(163)	(43)							0	0	0	0							(2,962)	(1,623)	(163)	(43)
Inventories Carried At Market						0					0					15,426					15,405					0					0					15,426					15,405
Unrealized Gain (Loss) on Derivatives	199	1,215	942	1,897			0	0	0	0							(98)	(396)	64	(327)							0	0	0	0							(98)	(396)	64	(327)
Business Acquisition, Contingent Consideration, at Fair Value					$ 0	$ 0									$ 0	$ 0									$ 3,245	$ 4,398									$ 3,245	$ 4,398