Note 15 - Stock-based Compensation - Share-based Award Expense Activity (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based compensation expense	$ 4,824	$ 1,443	$ 6,075	$ 2,038
Employee Stock Option [Member]
Share-based compensation expense	141	80	197	172
Restricted Stock [Member]
Share-based compensation expense	620	460	1,364	963
Performance Shares [Member]
Share-based compensation expense	$ 4,063	$ 903	$ 4,514	$ 903

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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