Note 7 - Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 3,835,000	$ 2,442,000
(Basic) (in shares)	14,350,721	13,927,063
Common stock equivalents (in shares)	578,974	741,595
Weighted average shares outstanding - diluted (in shares)	14,929,695	14,668,658
Weighted average number of shares outstanding during the period
Net earnings (in dollars per share)	$ 0.27	$ 0.18
Net earnings (in dollars per share)	$ 0.26	$ 0.17