Note 6 - Securities - (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale, Restricted	$ 165,900,000	$ 172,200,000
Debt Securities, Available-for-sale, Realized Gain	112,000	7,000	$ 31,000
Debt Securities, Available-for-sale, Realized Loss	6,000	0	$ 0
Other Equity Securities, Fair Value Disclosure	12,565,000	9,282,000
The Independent Bankers Bank [Member]
Other Equity Securities, Fair Value Disclosure	202,000	202,000
Bankers Insurance LLC [Member]
Other Equity Securities, Fair Value Disclosure	310,000	621,000
First National Bankers Bank [Member]
Other Equity Securities, Fair Value Disclosure	655,000	655,000
Mc Larty Capital Partners SBIC L.P [Member]
Other Equity Securities, Fair Value Disclosure	1,900,000	1,500,000
McLarty Capital Partners SBIC II, L.P. [Member]
Other Equity Securities, Equity Method	1,800,000	1,600,000
Bluehenge Capital Secured Debt SBIC L.P [Member]
Other Equity Securities, Equity Method	1,600,000	1,100,000
New Louisiana Angel Fund 2, LLC [Member]
Other Equity Securities, Equity Method	12,000	13,000
Federal Home Loan Bank of Dallas [Member]
Other Equity Securities, Fair Value Disclosure	$ 6,100,000	$ 3,600,000