Note 9 - Leases (Details Textual)	12 Months Ended
	Dec. 31, 2021 USD ($) ft²	Dec. 31, 2020 USD ($)	Jan. 01, 2019 USD ($)
Operating Lease, Right-of-Use Asset	$ 571,000	$ 730,000
Operating Lease, Payments	$ 310,000	$ 301,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset			$ 966,000
Facility Located in Rancho Cordova, California [Member]
Area of Real Estate Property (Square Foot) | ft²	28,000