Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parentheticals) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Retained Earnings [Member]
Cash dividends on common stock, per share (in dollars per share)	$ 0.15	$ 0.14	$ 0.45	$ 0.42
Common Stock [Member]
Issuance of common stock, dividend reinvestment plan, shares (in shares)	2,295	2,733	7,047	7,853
Issuance of common stock, stock incentive plan, shares (in shares)			33,002	34,634
Stock Repurchase Plan [Member]
Repurchase of common stock shares (in shares)	3,674
First National Corporation 2014 Stock Incentive Plan [Member]
Repurchase of common stock shares (in shares)			6,495	8,283
Issuance of common stock, stock incentive plan, shares (in shares)	6,495	7,500
Repurchase of common stock shares (in shares)			37,532