Note 4 - Commitments & Contingencies (Details Textual) ft² in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 25, 2021 USD ($) ft²	Sep. 26, 2020 USD ($)	Sep. 25, 2021 USD ($) ft²
Area of Real Estate Property (Square Foot) \| ft²	38		38
Operating Lease, Payments	$ 38	$ 114
Minimum [Member]
Lessee, Operating Lease, Annual Rent Payments			$ 152
Maximum [Member]
Lessee, Operating Lease, Annual Rent Payments			$ 165

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980

Name:	us-gaap_OperatingLeasePayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration