Note 4 - Earnings Per Share - Shares Used in Calculation of Earnings Per Share (Details) - shares	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Weighted-average common shares issued (in shares)	3,635,304	3,606,427
Average treasury stock shares (in shares)	(386,165)	(386,165)
Weighted-average common shares and common stock equivalents used to calculate basic earnings per share (in shares)	3,249,139	3,220,262
Additional common stock equivalents (stock options and restricted stock) used to calculate diluted earnings per share (in shares)	6,145	17,807
Weighted-average common shares and common stock equivalents used to calculate diluted earnings per share (in shares)	3,255,284	3,238,069

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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