Note 5 - Deposits - Summary of Deposits (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Noninterest-bearing	$ 918,581,000	$ 889,784,000
Noninterest-bearing checking, percentage	35.10%	36.10%
Noninterest-bearing checking, percent increase (decrease)	3.20%
Interest-bearing checking	$ 286,531,000	$ 339,089,000
Interest-bearing checking, percentage	10.90%	13.80%
Interest-bearing checking, percent increase (decrease)	(15.50%)
Money market	$ 484,177,000	$ 434,333,000
Money market, percentage	18.50%	17.60%
Money market, percent increase (decrease)	11.50%
Savings	$ 270,563,000	$ 317,014,000
Savings, percentage	10.30%	12.90%
Savings, percent increase (decrease)	(14.70%)
Local Time, under $100,000	$ 205,452,000	$ 160,092,000
Local Time, under $100,000, percentage	7.80%	6.50%
Local Time, under $100,000, percent increase (decrease)	28.30%
Local Time, $100,000 and over	$ 284,460,000	$ 210,164,000
Local Time, $100,000 and over, percentage	10.90%	8.50%
Local Time, $100,000 and over, percent increase (decrease)	35.40%
Total local deposits	$ 2,449,764,000	$ 2,350,476,000
Total local deposits, percentage	93.50%	95.40%
Total local deposits, percent increase (decrease)	4.20%
Out-of-area time, under $100,000	$ 0	$ 0
Out-of-area time, under $100,000, percentage
Out-of-area time, under $100,000, percent increase (decrease)
Out-of-area time, $100,000 and over	$ 169,445,000	$ 113,232,000
Out-of-area time, $100,000 and over, percentage	6.50%	4.60%
Out-of-area time, $100,000 and over, percent increase (decrease)	49.60%
Total out-of-area deposits	$ 169,445,000	$ 113,232,000
Total out-of-area deposits, percentage	6.50%	4.60%
Total out-of-area deposits, percent increase (decrease)	49.60%
Total deposits	$ 2,619,209,000	$ 2,463,708,000
Total deposits, percentage	100.00%	100.00%
Total deposits, percent increase (decrease)	6.30%