Note 3 - Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Beginning balance	$ 5,506	$ 5,200
Additions based on tax positions taken in prior years		306
Reductions as a result of a lapse of the applicable statute of limitations	(2,753)
Reductions as a result of tax positions taken during prior periods	(93)
Ending balance	$ 2,660	$ 5,506

Amount of unrecognized tax benefits.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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