Note 15 - Common Stock (Details Textual) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Percentage of Common Stock A Held By One Shareholder Without Any Common Stock B	21.60%
Dividends, Common Stock, Total	$ 3.4	$ 3.4
Common Class A [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.24	$ 0.24
Common Class A [Member] \| Quarterly Dividends [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	0.06	0.06
Common Class B [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	0.28	0.28
Common Class B [Member] \| Quarterly Dividends [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.07	$ 0.07

The percentage of common stock A shares held by one shareholder that does not hold any common class B shares.

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- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

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- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

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