Note 2 - Goodwill and Purchased Intangible Assets - Changes in Carrying Value of Goodwill (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 28, 2020		Dec. 28, 2019
Beginning balance		$ 238,669	[1]	$ 242,127
Adjustments				1,134
Impairments	[2]			(715)
Impact of currency exchange		(672)		(3,877)
Ending balance		237,997		238,669	[1]
Semiconductor Test and Inspection [Member]
Beginning balance		218,775		220,808
Adjustments				2,117
Impairments	[2]			(715)
Impact of currency exchange		(575)		(3,435)
Ending balance		218,200		218,775
PCB Test [Member]
Beginning balance		19,894		21,319
Adjustments				(983)
Impairments	[2]
Impact of currency exchange		(97)		(442)
Ending balance		$ 19,797		$ 19,894

[1] Derived from December 28, 2019 audited financial statements

[2] Impairment of goodwill associated with our FSG segment that is presented as discontinued operations. This amount was not pushed down in the consolidated financial statements and was included within the balance of our Semiconductor Test & Inspection segment.