Note 9 - Accrued Retirement Benefits - Accrued Retirement Benefits (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Accrued retirement benefits	$ 2,761	$ 2,754
Less current portion	142	142
Non-current portion of accrued retirement benefits	2,619	2,612
Pension Plan [Member] \| Qualified Plan [Member]
Accrued retirement benefits	1,041	1,023
Supplemental Employee Retirement Plan [Member] \| Nonqualified Plan [Member]
Accrued retirement benefits	$ 1,720	$ 1,731

Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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