Note 10 - FHLB Advances - Maturity and Interest Rate Information on Advances from FHLB (Details) - USD ($)		Dec. 31, 2017	Dec. 31, 2016
2017, Amount due		$ 190,400,000
2017, Weighted average interest rate at year-end		1.82%
2020, Amount due		$ 1,600,000
2020, Weighted average interest rate at year-end		1.75%
Total FHLB advances, Amount due		$ 192,000,000
Total FHLB advances, Weighted average interest rate at year-end		1.82%
Federal Home Loan Bank, Advances, Putable Option [Member]
2017, Amount due	[1]		$ 112,500,000
2017, Weighted average interest rate at year-end			0.78%
2018, Amount due	[1]		$ 25,000,000
2018, Weighted average interest rate at year-end			3.35%
2020, Amount due
2020, Weighted average interest rate at year-end
Total FHLB advances, Amount due	[1]		$ 137,500,000
Total FHLB advances, Weighted average interest rate at year-end			1.25%

[1] Of the advances outstanding, a portion have putable options which allow the FHLB, at its discretion, to terminate the advances and require the subsidiary banks to repay at predetermined dates prior to the stated maturity date of the advances.