Note 13 - Accounting for Stock-based Compensation - Stock-based Compensation Activity (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-Based Compensation Recognized	$ 15,943	$ 14,741	$ 13,435
Stock-Based Compensation Unrecognized	$ 33,624
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)
Employee Stock Option [Member]
Stock-Based Compensation Recognized	$ 909	1,546	1,866
Stock-Based Compensation Unrecognized	$ 134
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	73 days
Restricted Stock Units (RSUs) [Member]
Stock-Based Compensation Recognized	$ 6,325	7,409	7,881
Stock-Based Compensation Unrecognized	$ 14,030
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	2 years 146 days
Cash Settled RSUs [Member]
Stock-Based Compensation Recognized	$ 7,091	4,414	3,207
Stock-Based Compensation Unrecognized	$ 17,114
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	2 years 255 days
Non-Employee Director Awards [Member]
Stock-Based Compensation Recognized	$ 741	645	481
Stock-Based Compensation Unrecognized
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)
Performance Shares [Member]
Stock-Based Compensation Recognized	$ 877	$ 727
Stock-Based Compensation Unrecognized	$ 2,346
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	1 year 219 days

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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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