Note 8 - Subsequent Event (Details Textual) - Subsequent Event [Member] $ / shares in Units, $ in Millions	Nov. 20, 2018 USD ($) $ / shares
Common Stock, Dividends, Per Share, Declared \| $ / shares	$ 2.90
Dividends, Common Stock, Cash \| $	$ 135

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

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=27012166&loc=d3e187085-122770

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