Schedule of Geographic Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenue	$ 150,400	$ 119,102	$ 297,365	$ 228,076
UNITED STATES
Segment Reporting Information [Line Items]
Revenue	60,467	51,618	118,580	98,829
GERMANY
Segment Reporting Information [Line Items]
Revenue	21,012	14,781	41,081	29,079
Rest Of Europe
Segment Reporting Information [Line Items]
Revenue	23,347	14,430	50,407	28,012
CHINA
Segment Reporting Information [Line Items]
Revenue	18,367	13,986	33,970	25,461
Rest of Asia-Pacific
Segment Reporting Information [Line Items]
Revenue	24,987	20,877	49,707	40,742
Other Countries
Segment Reporting Information [Line Items]
Revenue	$ 2,220	$ 3,410	$ 3,620	$ 5,953