Note 13 - Retirement and Pension Plans - Percentage of Major Category of Plan Assets (Details)	Dec. 31, 2018	Dec. 31, 2017
Cash [Member]
Asset allocation	14.00%	20.00%
Debt Securities [Member]
Asset allocation	28.00%	30.00%
Equity Securities [Member]
Asset allocation	51.00%	43.00%

Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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