Note 2 - Common Stock Outstanding and Earnings Per Share - Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Net income		$ 4,032	$ 2,876	$ 10,891	$ 7,337	$ 7,344
Weighted average shares - basic (in shares)	[1]	16,252	16,191	16,242	14,884
Effect of potentially dilutive common shares (2) (in shares)	[2]	90	97	85	100
Weighted average number of common shares outstanding - diluted (in shares)		16,342	16,288	16,327	14,984
Earnings per share - basic (in dollars per share)		$ 0.25	$ 0.18	$ 0.67	$ 0.49
Earnings per share - diluted (in dollars per share)		$ 0.25	$ 0.18	$ 0.67	$ 0.49
Employee Stock Option [Member]
Anti-dilutive options not included in diluted earnings per share calculation (in shares)			70		74
Restricted Stock [Member]
Anti-dilutive options not included in diluted earnings per share calculation (in shares)			42		43

[1] Excludes unvested restricted shares because they do not have dividend or voting rights

[2] Represents the effects of the assumed exercise of stock options and vesting of non-participating restricted shares.