Other expense (income), net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Other Nonoperating Income (Expense) [Abstract]
Foreign currency losses (gains), net	$ 3,317	$ 5,008	$ 4,722	$ 2,685
Release of indemnification asset	0	0	1,749	0
All other, net	(1,227)	(2,006)	(383)	(2,515)
Total other expense, net	$ 2,090	$ 3,002	$ 6,088	$ 170