Note 8 - Deposits - Summary of Deposits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Noninterest-bearing demand	$ 810,600,000	$ 674,568,000
Noninterest-bearing demand	34.10%	29.60%
Noninterest-bearing demand	20.20%
Interest-bearing checking	$ 377,929,000	$ 403,354,000
Interest-bearing checking	15.90%	17.70%
Interest-bearing checking	(6.30%)
Money market	$ 272,051,000	$ 274,395,000
Money market	11.50%	12.10%
Money market	(0.90%)
Savings	$ 344,988,000	$ 332,794,000
Savings	14.50%	14.60%
Savings	3.70%
Time, under $100,000	$ 146,169,000	$ 155,655,000
Time, under $100,000	6.20%	6.90%
Time, under $100,000	(6.10%)
Time, $100,000 and over	$ 423,248,000	$ 434,467,000
Total local deposits	$ 2,298,795,000	$ 2,154,013,000
Total local deposits	96.80%	94.70%
Total local deposits	6.70%
Out-of-area time, under $100,000	$ 0	$ 149,000
Out-of-area time, under $100,000	0.00%	0.10%
Out-of-area time, under $100,000	0.00%
Out-of-area time, $100,000 and over	$ 76,190,000	$ 121,220,000
Out-of-area time, $100,000 and over	3.20%	5.30%
Out-of-area time, $100,000 and over	(37.10%)
Total out-of-area deposits	$ 76,190,000	$ 121,369,000
Total out-of-area deposits	3.20%	5.30%
Total out-of-area deposits	(37.20%)
Total deposits	$ 2,374,985,000	$ 2,275,382,000
Total deposits	100.00%	100.00%
Total deposits	4.40%
Geographic Distribution, Domestic [Member]
Time, $100,000 and over	$ 347,058,000	$ 313,247,000
Time, $100,000 and over	14.60%	13.80%
Time, $100,000 and over	10.80%