Note 6 - Accrued Retirement Benefits - Summary of Assumptions Used (Details)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Expected long-term return on plan assets	5.00%	7.00%
Expected long-term return on plan assets	5.00%	5.32%
Minimum [Member]
Discount rate	4.07%	4.30%
Discount rate	4.30%	3.96%
Maximum [Member]
Discount rate	4.14%	4.44%
Discount rate	4.44%	4.07%

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

The interest rate used to adjust for the time value of money for the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

The interest rate used to adjust for the time value of money.

+ References

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- Definition

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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