Note 5 - Deposits - Summary of Deposits (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Noninterest-bearing demand	$ 757,706,000	$ 810,600,000
Noninterest-bearing demand	33.30%	34.10%
Noninterest-bearing demand	(6.50%)
Interest-bearing checking	$ 371,622,000	$ 377,929,000
Interest-bearing checking	16.30%	15.90%
Interest-bearing checking	(1.70%)
Money market	$ 279,120,000	$ 272,051,000
Money market	12.30%	11.50%
Money market	2.60%
Savings	$ 355,354,000	$ 344,988,000
Savings	15.60%	14.50%
Savings	3.00%
Time, under $100,000	$ 142,454,000	$ 146,169,000
Time, under $100,000	6.20%	6.20%
Time, under $100,000	(2.50%)
Total local deposits	$ 2,232,950,000	$ 2,298,795,000
Total local deposits	98.00%	96.80%
Total local deposits	(2.90%)
Out-of-area time, under $100,000	$ 0	$ 0
Out-of-area time, $100,000 and over	$ 45,066,000	$ 76,190,000
Out-of-area time, $100,000 and over	2.00%	3.20%
Out-of-area time, $100,000 and over	(40.90%)
Total out-of-area deposits	$ 45,066,000	$ 76,190,000
Total out-of-area deposits	2.00%	3.20%
Total out-of-area deposits	(40.90%)
Deposits	$ 2,278,016,000	$ 2,374,985,000
Total deposits	100.00%	100.00%
Aggregate Increase (Decrease) in Percentage of Deposits	(4.10%)
Geographic Distribution, Domestic [Member]
Time, $100,000 and over	$ 326,694,000	$ 347,058,000
Time, $100,000 and over	14.30%	14.60%
Time, $100,000 and over	(5.90%)