Note 10 - Discontinued Operations - Balance Sheet Information and Operating Results for Fixture Services Business (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018	Dec. 29, 2018
Assets:
Total current assets	$ 3,733		$ 3,733		$ 3,741	[1]
Total assets	3,863		3,863		3,820
Liabilities:
Total current liabilities	564		564		518	[1]
Noncurrent liabilities	34		34			[1]
Income, net of tax	154		342
Xcerra [Member]
Liabilities:
Net sales	1,720		5,020
Operating income before income taxes	173		400
Income tax provision	19		58
Income, net of tax	154		342
Xcerra [Member] | Discontinued Operations, Held-for-sale [Member]
Assets:
Cash and cash equivalents	1,176		1,176		461
Accounts receivable, net	1,466		1,466		1,718
Inventories	1,074		1,074		1,388
Other current assets	17		17		174
Total current assets	3,733		3,733		3,741
Property, plant and equipment, net	40		40		66
Other noncurrent assets	90		90		13
Total assets	3,863		3,863		3,820
Liabilities:
Other accrued current liabilities	564		564		518
Total current liabilities	564		564		518
Noncurrent liabilities	34		34
Total liabilities	$ 598		$ 598		$ 518

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