Note 8 - Cash Dividend (Details Textual) - USD ($) $ / shares in Units, $ in Millions	Aug. 04, 2017	Jun. 05, 2017	May 05, 2017
Common Stock, Dividends, Per Share, Declared			$ 1.50
Payments of Ordinary Dividends, Common Stock	$ 69.9
Dividends Payable, Date of Record		Jun. 05, 2017

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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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration