Note 5 - Deposits - Summary of Deposits (Details) - USD ($)	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Noninterest-bearing demand	$ 1,740,432,000	$ 1,677,952,000
Noninterest-bearing demand, percentage	44.90%	41.10%
Noninterest-bearing demand, percent increase (decrease)	3.70%
Interest-bearing checking	$ 481,016,000	$ 538,838,000
Interest-bearing checking, percentage	12.40%	13.20%
Interest-bearing checking, percent increase (decrease)	(10.70%)
Money market	$ 889,035,000	$ 1,040,176,000
Money market, percentage	23.00%	25.50%
Money market, percent increase (decrease)	(14.50%)
Savings	$ 409,505,000	$ 394,330,000
Savings, percentage	10.60%	9.70%
Savings, percent increase (decrease)	3.80%
Local Time, under $100,000	$ 120,930,000	$ 132,776,000
Local Time, under $100,000, percentage	3.10%	3.20%
Local Time, under $100,000, percent increase (decrease)	(8.90%)
Local Time, $100,000 and over	$ 232,975,000	$ 275,208,000
Local Time, $100,000 and over, percentage	6.00%	6.70%
Local Time, $100,000 and over, percent increase (decrease)	(15.30%)
Total local deposits	$ 3,873,893,000	$ 4,059,280,000
Total local deposits, percentage	100.00%	99.40%
Total local deposits, percent increase (decrease)	(4.60%)
Out-of-area time, $100,000 and over	$ 0	$ 23,913,000
Out-of-area time, $100,000 and over, percentage	0.00%	0.60%
Out-of-area time, $100,000 and over, percent increase (decrease)	(100.00%)
Total deposits	$ 3,873,893,000	$ 4,083,193,000
Total deposits, percentage	100.00%	100.00%
Total deposits, percent increase (decrease)	(5.10%)