Note 2 - Business Combinations - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
		Aug. 01, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Bargain purchase gain	[1]		$ 17,827	$ 0	$ 17,827	$ 0
Northumberland Bancorp [Member]
Mifflinburg Bancorp, Inc. shares to be issued (in shares)		1,546,725
Per share value assigned to shares issued (in dollars per share)		$ 26
Total purchase price assigned to shares issued		$ 40,215
Fair value of total consideration transferred		40,405
Cash and cash equivalents		43,589
Securities, available for sale		165,660
Loans held for sale		61
Loans gross		427,066
Allowance for credit losses		(725)
Loans, net of allowance		426,341
Bank owned life insurance		14,848
Accrued interest receivable		2,261
Restricted investment in bank stock		2,948
Deferred tax asset		2,849
Operating lease right of use asset		132
Other assets		3,679
Total identifiable assets acquired at fair value		688,177
Deposits		597,060
Borrowings		20,117
Subordinated debt		9,753
Accrued interest payable		554
Operating lease liability		132
Other liabilities		2,329
Total liabilities assumed		629,945
Total identifiable net assets, at fair value		58,232
Bargain purchase gain		17,827
Northumberland Bancorp [Member] | Core Deposits [Member]
Intangibles		14,662
Northumberland Bancorp [Member] | Customer Lists [Member]
Intangibles		1,406
Northumberland Bancorp [Member] | Premises [Member]
Property, Plant, and Equipment		9,226
Northumberland Bancorp [Member] | Furniture, Fixtures and Equipment [Member]
Property, Plant, and Equipment		515
Northumberland Bancorp [Member] | Fractional Shares [Member]
Cash payment		3
Northumberland Bancorp [Member] | Dissenter's Shares [Member]
Cash payment		$ 187
Dissenter's shares (1) (in shares)	[2]	6,493
Fair value of Dissenter's shares (in dollars per share)		$ 28.8

[1] Not within the scope of ASC 606

[2] NUBC stockholder with 6,493 shares exercised their Dissenter’s rights. The Company made a settlement with the stockholder and paid a cash settlement of $28.80 per share for a total payment of $187 thousand.