Note 9 - Stockholders' Equity - Summary of Repurchases (Details) - Restricted Stock Units (RSUs) [Member] - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Shares of common stock repurchased (in shares)	21,410	27,291
Average per share repurchase price (in dollars per share)	$ 34.62	$ 28.51
Aggregage purchase price (in thousands)	$ 741	$ 778

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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