Note 9 - Share-based Compensation and Cash-based Incentive Compensation (Details Textual) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2019 USD ($) shares	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant \| shares	11,852,592
Restricted Stock [Member]
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Grant Date Fair Value	$ 0.3
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	0.5
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	0.4
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 5.9
Directors Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant \| shares	82,620
Shares Issued, Shares, Share-based Payment Arrangement, Forfeited \| shares	0
Number of Cash-based Awards		2

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-Section 50
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