Note 6 - Accrued Retirement Benefits - Summary of Assumptions Used (Details)	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Expected long-term return on plan assets	5.00%	4.00%
Minimum [Member]
Discount rate	5.11%	2.69%
Discount rate	2.69%
Maximum [Member]
Discount rate	5.14%	2.74%

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

No definition available.

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

+ References

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