Note 12 - Income Taxes - Summary of Gross Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Beginning of year	$ 26,000	$ 32,000
Settlements and effective settlements with tax authorities
Lapse of statute of limitations	(7,000)	(6,000)
Decrease to tax positions taken during prior periods	(3,000)	(6,000)
Increase to tax positions taken during current period	6,000	6,000
End of year	$ 22,000	$ 26,000

Amount of unrecognized tax benefits.

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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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