Note 7 - Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net income	$ 4,341,000	$ 3,308,000	$ 8,176,000	$ 5,750,000
(Basic) (in shares)	14,501,399	14,120,617	14,426,060	14,023,840
Common stock equivalents (in shares)	539,032	836,852	559,003	789,224
Weighted average shares outstanding - diluted (in shares)	15,040,431	14,957,469	14,985,063	14,813,064
Weighted average number of shares outstanding during the period
Net earnings (in dollars per share)	$ 0.30	$ 0.23	$ 0.57	$ 0.41
Net earnings (in dollars per share)	$ 0.29	$ 0.22	$ 0.55	$ 0.39