Schedule of Geographic Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2020	Sep. 27, 2019	Oct. 02, 2020	Sep. 27, 2019
Segment Reporting Information [Line Items]
Revenue	$ 142,929	$ 154,066	$ 443,125	$ 466,397
United States
Segment Reporting Information [Line Items]
Revenue	57,635	63,278	171,364	190,048
Germany
Segment Reporting Information [Line Items]
Revenue	18,885	21,423	64,266	63,738
Rest of Europe
Segment Reporting Information [Line Items]
Revenue	30,483	30,489	94,281	97,230
China
Segment Reporting Information [Line Items]
Revenue	17,409	11,895	50,285	42,395
Rest of Asia-Pacific
Segment Reporting Information [Line Items]
Revenue	16,414	24,218	55,956	65,367
Other Countries
Segment Reporting Information [Line Items]
Revenue	$ 2,103	$ 2,763	$ 6,973	$ 7,619