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Note 2 - Business Combination - Schedule of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Jun. 01, 2025	Sep. 30, 2026	Dec. 31, 2025	Sep. 30, 2025
Goodwill		$ 220,235	$ 220,235
First of Long Island Corporation [Member]
Total purchase price consideration	$ 270,828
Cash and cash equivalents	54,869
Available-for-sale securities	596,702
Premises and equipment, net	45,895
Pension plan assets	11,617
Core deposit intangible	63,206
Other assets	102,856
Total assets acquired	3,900,470
Deposits	3,251,147
Borrowings	360,405
Other liabilities	29,953
Total liabilities assumed	3,641,505
Net assets acquired	258,965
Goodwill	11,863	$ 11,900		$ 7,200
First of Long Island Corporation [Member] \| Loans Receivable [Member]
Financial assets	2,882,951
First of Long Island Corporation [Member] \| Investment in Restricted Stock [Member]
Financial assets	24,276
First of Long Island Corporation [Member] \| Bank-owned Life Insurance [Member]
Financial assets	118,098
First of Long Island Corporation [Member] \| Reported Value by Acquiree [Member]
Total purchase price consideration	270,828
Cash and cash equivalents	54,869
Available-for-sale securities	596,702
Premises and equipment, net	45,895
Pension plan assets	11,617
Core deposit intangible	63,206
Other assets	107,480
Total assets acquired	3,905,094
Deposits	3,251,147
Borrowings	360,405
Other liabilities	29,953
Total liabilities assumed	3,641,505
Net assets acquired	263,589
Goodwill	7,239
First of Long Island Corporation [Member] \| Reported Value by Acquiree [Member] \| Loans Receivable [Member]
Financial assets	2,882,951
First of Long Island Corporation [Member] \| Reported Value by Acquiree [Member] \| Investment in Restricted Stock [Member]
Financial assets	24,276
First of Long Island Corporation [Member] \| Reported Value by Acquiree [Member] \| Bank-owned Life Insurance [Member]
Financial assets	118,098
First of Long Island Corporation [Member] \| Fair Value Adjustments [Member]
Other assets	(4,624)
Total assets acquired	(4,624)
Net assets acquired	(4,624)
Goodwill	$ 4,624