Note 5 - Deposits - Summary of Deposits (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Noninterest-bearing checking	$ 800,718,000	$ 810,600,000
Noninterest-bearing checking	33.80%	34.10%
Noninterest-bearing checking	(1.20%)
Interest-bearing checking	$ 372,727,000	$ 377,929,000
Interest-bearing checking	15.70%	15.90%
Interest-bearing checking	(1.40%)
Money market	$ 348,715,000	$ 272,051,000
Money market	14.70%	11.50%
Money market	28.20%
Savings	$ 344,987,000	$ 344,988,000
Savings	14.60%	14.50%
Time, under $100,000	$ 149,806,000	$ 146,169,000
Time, under $100,000	6.30%	6.20%
Time, under $100,000	2.50%
Total local deposits	$ 2,277,082,000	$ 2,298,795,000
Total local deposits	96.10%	96.80%
Total local deposits	(0.90%)
Out-of-area time, under $100,000	$ 0	$ 0
Out-of-area time, $100,000 and over	$ 93,639,000	$ 76,190,000
Out-of-area time, $100,000 and over	3.90%	3.20%
Out-of-area time, $100,000 and over	22.90%
Total out-of-area deposits	$ 93,639,000	$ 76,190,000
Total out-of-area deposits	3.90%	3.20%
Total out-of-area deposits	22.90%
Deposits	$ 2,370,721,000	$ 2,374,985,000
Total deposits	100.00%	100.00%
Aggregate Increase (Decrease) in Percentage of Deposits	(0.20%)
Geographic Distribution, Domestic [Member]
Time, $100,000 and over	$ 260,129,000	$ 347,058,000
Time, $100,000 and over	11.00%	14.60%
Time, $100,000 and over	(25.00%)