Note 2 - Mergers and Acquisitions - Changes in carrying amount of intangibles (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Jul. 01, 2018
Business Acquisition [Line Items]
Balance at acquisition				$ 9,078,953
Amortization expense	$ (541,665)		$ (230,867)	(1,150,767)	$ (692,600)
Balance at the end of the period	16,136,914	$ 16,136,914	6,688,613	16,136,914	6,688,613
Finite-Lived Intangible Assets, Net [Abstract]
Net book value	16,136,914	16,136,914	6,688,613	9,078,953	6,688,613	$ 16,136,914
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Net book value	16,136,914	16,136,914	$ 6,688,613	9,078,953	$ 6,688,613	16,136,914
Springfield Bancshares | Core Deposits [Member]
Business Acquisition [Line Items]
Balance at acquisition		8,208,728
Amortization expense		(237,114)
Balance at the end of the period	7,971,614	7,971,614		7,971,614
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount							$ 8,208,728
Accumulated amortization						(237,114)
Net book value	7,971,614	8,208,728		7,971,614		7,971,614	8,208,728
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2018						237,114
2019						932,810
2020						915,051
2021						893,192
2022						867,227
Thereafter						4,126,220
Net book value	$ 7,971,614	$ 8,208,728		$ 7,971,614		$ 7,971,614	$ 8,208,728