Segment information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 652,507	$ 609,866	$ 1,266,091	$ 1,197,096
Operating profit	107,458	33,490	182,701	120,333
Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating profit	136,480	108,148	252,402	221,192
Unallocated expenses
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating profit	(29,022)	(74,658)	(69,701)	(100,859)
Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	373,804	331,444	717,828	654,706
Americas | Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating profit	82,509	47,315	148,108	106,205
EMEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	147,047	153,415	301,592	313,285
EMEA | Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating profit	20,827	26,535	47,850	58,305
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	75,228	72,413	136,005	130,657
Asia | Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating profit	19,260	20,746	29,239	34,114
OEM
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	56,428	52,594	110,666	98,448
OEM | Operating Segments
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating profit	$ 13,884	$ 13,552	$ 27,205	$ 22,568