Note 6 - Securities - (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-Sale, Restricted	$ 482,700,000	$ 373,400,000
Debt Securities, Available-for-Sale, Realized Gain	9,000	593,000	$ 293,000
Debt Securities, Available-for-Sale, Realized Loss	57,000	215,000	158,000
Other Equity Securities, Fair Value Disclosure	37,467,000	16,619,000
The Independent Bankers Bank [Member]
Other Equity Securities, Fair Value Disclosure	302,000	302,000
Bankers Insurance LLC [Member]
Other Equity Securities, Fair Value Disclosure	562,000	562,000
First National Bankers Bank [Member]
Other Equity Securities, Fair Value Disclosure	2,200,000		$ 2,000,000.0
Senior Housing Crime Prevention Foundation [Member]
Other Equity Securities, Fair Value Disclosure	501,000	502,000
Federal Home Loan Bank of Dallas [Member]
Other Equity Securities, Fair Value Disclosure	$ 19,700,000	$ 5,300,000