Note 1 - Summary of Significant Accounting Policies and Other Information (Details Textual) - Accounting Standards Update 2016-01 [Member] $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
Cumulative Effect on Retained Earnings, Net of Tax, Total	$ 9.8
Equity Securities, FV-NI, Unrealized Gain (Loss), Total	$ 2.8

Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117546-209714

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Balance Type:	credit
Period Type:	duration