Note 7 - Deposits - Summary of Deposits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Noninterest-bearing checking	$ 1,677,952,000	$ 1,433,403,000
Noninterest-bearing checking, percentage	41.10%	42.00%
Noninterest-bearing checking, percent increase (decrease)	17.10%
Interest-bearing checking	$ 538,838,000	$ 473,053,000
Interest-bearing checking, percentage	13.20%	13.90%
Interest-bearing checking, percent increase (decrease)	13.90%
Money market	$ 1,040,176,000	$ 611,912,000
Money market, percentage	25.50%	17.90%
Money market, percent increase (decrease)	70.00%
Savings	$ 394,330,000	$ 338,070,000
Savings, percentage	9.70%	9.90%
Savings, percent increase (decrease)	16.60%
Local Time, under $100,000	$ 132,776,000	$ 165,548,000
Local Time, under $100,000, percentage	3.20%	4.90%
Local Time, under $100,000, percent increase (decrease)	(19.80%)
Local Time, $100,000 and over	$ 275,208,000	$ 342,633,000
Local Time, $100,000 and over, percentage	6.70%	10.00%
Local Time, $100,000 and over, percent increase (decrease)	(19.70%)
Total local deposits	$ 4,059,280,000	$ 3,364,619,000
Total local deposits, percentage	99.40%	98.60%
Total local deposits, percent increase (decrease)	20.60%
Out-of-area time, $100,000 and over	$ 23,913,000	$ 46,934,000
Out-of-area time, $100,000 and over, percentage	0.60%	1.40%
Out-of-area time, $100,000 and over, percent increase (decrease)	(49.00%)
Total deposits	$ 4,083,193,000	$ 3,411,553,000
Total deposits, percentage	100.00%	100.00%
Total deposits, percent increase (decrease)	19.70%