Note 5 - Deposits - Summary of Deposits (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Noninterest-bearing checking	$ 826,038,000	$ 810,600,000
Noninterest-bearing checking	33.20%	34.10%
Noninterest-bearing checking	1.90%
Interest-bearing checking	$ 405,223,000	$ 377,929,000
Interest-bearing checking	16.30%	15.90%
Interest-bearing checking	7.20%
Money market	$ 404,336,000	$ 272,051,000
Money market	16.20%	11.50%
Money market	48.60%
Savings	$ 333,495,000	$ 344,988,000
Savings	13.40%	14.50%
Savings	(3.30%)
Time, under $100,000	$ 151,049,000	$ 146,169,000
Time, under $100,000	6.10%	6.20%
Time, under $100,000	3.30%
Total local deposits	$ 2,384,388,000	$ 2,298,795,000
Total local deposits	95.80%	96.80%
Total local deposits	3.70%
Out-of-area time, under $100,000	$ 0	$ 0
Out-of-area time, $100,000 and over	$ 104,655,000	$ 76,190,000
Out-of-area time, $100,000 and over	4.20%	3.20%
Out-of-area time, $100,000 and over	37.40%
Total out-of-area deposits	$ 104,655,000	$ 76,190,000
Total out-of-area deposits	4.20%	3.20%
Total out-of-area deposits	37.40%
Deposits	$ 2,489,043,000	$ 2,374,985,000
Total deposits	100.00%	100.00%
Aggregate Increase (Decrease) in Percentage of Deposits	4.80%
Geographic Distribution, Domestic [Member]
Time, $100,000 and over	$ 264,247,000	$ 347,058,000
Time, $100,000 and over	10.60%	14.60%
Time, $100,000 and over	(23.90%)