Note 10 - Stockholders' Equity - Summary of Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares of common stock repurchased for net settlement of equity awards (in shares)	16,333	16,537	20,524
Restricted Stock Units (RSUs) [Member]
Average per share repurchase price (in dollars per share)	$ 49.10	$ 34.47	$ 33.28
Aggregage purchase price (in thousands)	$ 802	$ 570	$ 683

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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