Note 5 - Loans and Allowance for Credit Losses (Details Textual) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Unamortized Loan Cost (Fee)	$ 601			$ 601		$ 248
Financing Receivable, Accrued Interest, after Allowance for Credit Loss	13,400			13,400		12,200
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	3,032,343			3,032,343		2,759,583
Off-Balance-Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	549			31	$ 44
Debt Securities, Held-to-Maturity, Credit Loss Expense (Reversal)	(14)			(76)	46
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	39,142	$ 38,332	$ 36,290	39,142	36,290	$ 35,843	$ 35,696	$ 31,146
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease)				3,300
Percentage of Increase in Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest						9.20%
Loans and Leases Receivables, Impaired, Troubled Debt, Interest Income	1,900		186
Financing Receivable, Nonaccrual, Interest Income	0		0
Commercial Borrower [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,122,945			2,122,945		$ 1,849,267
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	31,165	30,980	$ 26,631	31,165	$ 26,631	27,971	$ 25,582	$ 23,472
Commercial Borrower [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease)	4,200	$ 2,600
Asset Pledged as Collateral [Member] | Deposits [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,100,000			2,100,000		1,600
Metro Phoenix Bank [Member]
Financing Receivable, Unamortized Purchase Premium (Discount)	$ 3,800			$ 3,800		$ 5,100