Note 6 - Components of Share-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock [Member]
Share-based compensation	$ 27,898	$ 27,256	$ 25,606
Tax benefit	10,629	10,360	9,769
Allocated share-based compensation expense, net of tax	17,269	16,896	15,837
Performance Shares [Member]
Share-based compensation	9,330	7,882	5,941
Tax benefit	3,555	2,996	2,266
Allocated share-based compensation expense, net of tax	$ 5,775	4,886	3,675
Employee Stock Option [Member]
Share-based compensation		195	807
Tax benefit		74	308
Allocated share-based compensation expense, net of tax		121	499
Share-based compensation	$ 37,228	$ 35,333	$ 32,354

The amount of expense, net of income tax, 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.

No definition available.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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