Restructuring, acquisition and integration-related costs (Restructuring and Related Costs by Type of Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 04, 2015	Mar. 29, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring, acquisition and integration-related costs	$ 6,657	$ 4,661
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	9,844	2,059
Acquisition integration-related costs	132	3,578
Restructuring, acquisition and integration-related costs	9,976	5,637
Accelerated depreciation included in restructuring costs	4,360
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,173	2,602
Acquisition integration-related costs	1,380	3,486
Restructuring, acquisition and integration-related costs	$ 2,553	$ 6,088