Note 2 - Acquisition (Details Textual)					3 Months Ended		9 Months Ended
		Jun. 01, 2021 USD ($)		May 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Business Combination, Consideration Transferred, Total							$ 232,946,000
Proceeds from Sale of Debt Securities, Available-for-sale				$ 91,000,000			91,094,000	0
Goodwill, Purchase Accounting Adjustments					$ (699,000)	$ 0	(699,000)	0
Goodwill, Ending Balance					135,830,000	12,513,000	135,830,000	12,513,000	$ 136,529,000	$ 12,513,000	$ 12,513,000	$ 12,513,000
Business Combination, Acquisition Related Costs					525,000	$ 0	19,025,000	$ 0
Kentucky Bancshares [Member]
Business Combination, Consideration Transferred, Total		$ 232,946,000		$ 233,000,000
Number of Branches Acquired				19
Goodwill, Purchase Accounting Adjustments				$ (14,000,000.0)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles	[1]	999,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Prepaid and Other Assets		(70,000)	[2]		(70,000)
Goodwill, Ending Balance		$ 0		$ 123,000,000	123,000,000		123,000,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual					11,300,000		(15,700,000)
Kentucky Bancshares [Member] | Merger Related Credit Loss [Member]
Business Combination, Acquisition Related Costs							7,400,000
Kentucky Bancshares [Member] | Pre-tax Merger Expenses [Member]
Business Combination, Acquisition Related Costs							$ 19,000,000.0
Kentucky Bancshares [Member] | Core Deposits [Member]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles					$ 999,000

[1] Calculation of core deposit intangible related to the acquisition. During the third quarter of 2021, a recast adjustment of $999,000 was recorded based on revised inputs used in the calculation of the CDI attributed to KB, resulting in an increased intangible value.

[2] Adjustment to other assets to reflect the estimated fair value of prepaid and other assets. During the third quarter of 2021, a recast adjustment of $70,000 was recorded for the write off of miscellaneous mortgage servicing fees accrued in other assets by KB at acquisition, resulting in a reduction to other assets.