Note 13 - Retirement Benefit Plans - Assumptions (Details)	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Discount rate	4.75%	5.01%	2.46%
Discount rate	5.01%	2.46%	1.80%

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

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