Note 2 - Sales/Mergers/Acquisitions - Changes in Accretable Yield (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance at the beginning of the period	$ (10,794)	$ (6,471)	$ (9,310)
Discount added at acquisition		(8,093)	(2,444)
Accretion recognized	4,634	5,132	5,283
Balance at the end of the period	(6,435)	(10,794)	(6,471)
Performing Loans
Balance at the beginning of the period	(10,127)	(6,280)	(9,116)
Discount added at acquisition		(7,800)	(2,224)
Accretion recognized	3,749	4,423	5,060
Balance at the end of the period	(6,378)	(10,127)	(6,280)
Guaranty Bank and Trust Company [Member]
Balance at the beginning of the period	(1,621)	(2,363)	(2,444)
Reclassification of nonaccretable discount to accretable	(5)
Accretion recognized	525	742	81
Balance at the end of the period	(1,101)	(1,621)	(2,363)
Guaranty Bank and Trust Company [Member] | Performing Loans
Balance at the beginning of the period	(1,613)	(2,197)	(2,224)
Accretion recognized	518	584	27
Balance at the end of the period	(1,095)	(1,613)	(2,197)
Springfield Bancshares
Balance at the beginning of the period	(6,508)
Discount added at acquisition		(8,093)
Reclassification of nonaccretable discount to accretable	(159)	(892)
Accretion recognized	3,092	2,477
Balance at the end of the period	(3,575)	(6,508)
Springfield Bancshares | Performing Loans
Balance at the beginning of the period	(5,849)
Discount added at acquisition		(7,800)
Accretion recognized	2,325	1,951
Balance at the end of the period	(3,524)	(5,849)
PCI Loans
Balance at the beginning of the period	(667)	(191)	(194)
Discount added at acquisition		(293)	(220)
Reclassification of nonaccretable discount to accretable		892
Accretion recognized	885	709	223
Balance at the end of the period	(57)	(667)	(191)
PCI Loans | Guaranty Bank and Trust Company [Member]
Balance at the beginning of the period	(8)	(166)	(220)
Reclassification of nonaccretable discount to accretable	(5)
Accretion recognized	7	158	54
Balance at the end of the period	(6)	(8)	$ (166)
PCI Loans | Springfield Bancshares
Balance at the beginning of the period	(659)
Discount added at acquisition		(293)
Reclassification of nonaccretable discount to accretable	(159)	(892)
Accretion recognized	767	526
Balance at the end of the period	$ (51)	$ (659)