Note 5 - Deposits - Summary of Deposits (Details) - USD ($)	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Noninterest-bearing	$ 1,620,829,000	$ 1,433,403,000
Noninterest-bearing checking, percentage	44.10%	42.00%
Noninterest-bearing checking, percent increase (decrease)	13.10%
Interest-bearing checking	$ 477,151,000	$ 473,053,000
Interest-bearing checking, percentage	13.00%	13.90%
Interest-bearing checking, percent increase (decrease)	0.90%
Money market	$ 725,681,000	$ 611,912,000
Money market, percentage	19.80%	17.90%
Money market, percent increase (decrease)	18.60%
Savings	$ 387,783,000	$ 338,070,000
Savings, percentage	10.60%	9.90%
Savings, percent increase (decrease)	14.70%
Local Time, under $100,000	$ 142,531,000	$ 165,548,000
Local Time, under $100,000, percentage	3.90%	4.90%
Local Time, under $100,000, percent increase (decrease)	(13.90%)
Local Time, $100,000 and over	$ 286,383,000	$ 342,633,000
Local Time, $100,000 and over, percentage	7.80%	10.00%
Local Time, $100,000 and over, percent increase (decrease)	(16.40%)
Total local deposits	$ 3,640,358,000	$ 3,364,619,000
Total local deposits, percentage	99.20%	98.60%
Total local deposits, percent increase (decrease)	8.20%
Out-of-area time, $100,000 and over	$ 30,913,000	$ 46,934,000
Out-of-area time, $100,000 and over, percentage	0.80%	1.40%
Out-of-area time, $100,000 and over, percent increase (decrease)	(34.10%)
Total deposits	$ 3,671,271,000	$ 3,411,553,000
Total deposits, percentage	100.00%	100.00%
Total deposits, percent increase (decrease)	7.60%