Note 2 - Business Acquisitions, Goodwill and Purchased Intangible Assets - Acquired Goodwill Activity (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 28, 2019		Dec. 29, 2018
Balance		$ 242,127	[1]	$ 65,613
Additions, net				179,263
Impact of currency exchange		(7,358)		(2,749)
Adjustments	[2],[3]	1,134
Balance		235,903		242,127	[1]
Semiconductor Test and Inspection [Member]
Balance	[2]	220,808		65,613
Additions, net	[2]			157,661
Impact of currency exchange	[2]	(6,603)		(2,466)
Adjustments	[2],[3]	2,117
Balance	[2]	216,322		220,808
PCB Test [Member]
Balance		21,319
Additions, net				21,602
Impact of currency exchange		(755)		(283)
Adjustments	[2],[3]	(983)
Balance		$ 19,581		$ 21,319

[1] Derived from December 29, 2018 audited financial statements

[2] After the acquisition of Xcerra on October 1, 2018 we report in two segments, Semiconductor Test & Inspection and PCB Test. Prior year amounts would have been reported in our Semiconductor Test & Inspection segment and have been presented accordingly.

[3] Amounts represent adjustments made during the post-acquisition measurement period to the preliminary goodwill from the Xcerra acquisition.