Note 15 - Quarterly Financial Data (Unaudited) (Details Textual) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Restructuring Charges, Total									$ 18,704
Inventory Write-down									9,400
Amortization of Intangible Assets, Total	$ 11,600	$ 600	$ 700	$ 700	$ 700	$ 700	$ 600	$ 700	$ 17,197	$ 4,208	$ 6,903
Xcerra [Member]
Restructuring Charges, Total	37,800
Inventory Write-down	19,100
Severance Costs	17,800
Other Restructuring Costs	900
Amortization of Intangible Assets, Total	$ 13,100