Note 12 - Subsequent Events (Details Textual) - $ / shares		3 Months Ended
Jul. 17, 2019	Jun. 30, 2019	Jun. 30, 2018
Common Stock, Dividends, Per Share, Declared		$ 1	$ 1
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared	$ 1
Subsequent Event [Member] \| Common Stock [Member]
Dividends Payable, Date to be Paid	Aug. 30, 2019
Dividends Payable, Date of Record	Jul. 29, 2019

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
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Date the declared dividend will be paid, in CCYY-MM-DD format.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
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