Note 13 - Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 4,441,000	$ 4,447,000	$ 3,308,000	$ 2,442,000	$ 3,368,000	$ 4,031,000	$ 3,624,000	$ 2,043,000	$ 2,856,000	$ 3,368,000	$ 3,907,000	$ 1,218,000	$ 14,638,000	$ 13,066,000	$ 11,349,000
(Basic) (in shares)	14,162,939	14,118,354	14,120,617	13,927,063	13,894,907	13,833,561	13,730,646	13,584,922	13,481,494	13,375,566	13,207,804	13,128,946	14,082,243	13,761,009	13,298,452
Common stock equivalents (in shares)													815,246	817,635	566,246
Total weighted average shares outstanding - diluted (in shares)	14,979,746	14,984,084	14,957,469	14,668,658	14,603,464	14,585,688	14,577,342	14,548,084	14,252,310	14,004,202	13,648,540	13,553,740	14,897,489	14,578,644	13,864,698
Weighted average number of shares outstanding during the period
Net earnings (in dollars per share)	$ 0.31	$ 0.31	$ 0.23	$ 0.18	$ 0.24	$ 0.29	$ 0.26	$ 0.15	$ 0.21	$ 0.25	$ 0.30	$ 0.09	$ 1.04	$ 0.95	$ 0.85
Net earnings (in dollars per share)	$ 0.30	$ 0.30	$ 0.22	$ 0.17	$ 0.23	$ 0.28	$ 0.25	$ 0.14	$ 0.20	$ 0.24	$ 0.29	$ 0.09	$ 0.98	$ 0.90	$ 0.82