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Note 12 - Earnings Per Share (Details Textual) | 12 Months Ended
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Dec. 31, 2017
Common Class A [Member] |
Common Stock, Voting Rights | 1/20th of one vote per share
Common Class B [Member] |
Common Stock, Voting Rights | One full vote per share

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- Definition Description of voting rights of common stock. Includes eligibility to vote and votes per share owned. Include also, if any, unusual voting rights. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644 + Details
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