Note 11 - Subsequent Events (Details Textual) - $ / shares		3 Months Ended
Jul. 19, 2017	Jun. 30, 2017	Jun. 30, 2016
Common Stock, Dividends, Per Share, Declared		$ 1	$ 1
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared	$ 1

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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=27012166&loc=d3e187085-122770

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration