Restructuring, acquisition and integration-related costs (Restructuring and Related Costs by Type of Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 29, 2014	Mar. 30, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring, acquisition and integration-related costs	$ 4,661	$ 8,222
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2,059	3,006
Acquisition integration-related costs	3,578	405
Restructuring, acquisition and integration-related costs	5,637	3,411
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2,602	5,216
Acquisition integration-related costs	3,486	1,229
Restructuring, acquisition and integration-related costs	$ 6,088	$ 6,445