Note 9 - Securities Sold Under Agreement to Repurchase - Securities Sold Under Agreements to Repurchase by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Securities sold under agreements to repurchase	$ 21,629	$ 19,114
Maturity Overnight and Continuous [Member]
Securities sold under agreements to repurchase	21,629	19,114
Maturity Less than 30 Days [Member]
Securities sold under agreements to repurchase	0	0
Maturity 30 to 90 Days [Member]
Securities sold under agreements to repurchase	0	0
Maturity Greater than 90 Days [Member]
Securities sold under agreements to repurchase	0	0
Municipal Securities [Member]
Securities sold under agreements to repurchase	7,544	3,318
Municipal Securities [Member] | Maturity Overnight and Continuous [Member]
Securities sold under agreements to repurchase	7,544	3,318
Municipal Securities [Member] | Maturity Less than 30 Days [Member]
Securities sold under agreements to repurchase	0	0
Municipal Securities [Member] | Maturity 30 to 90 Days [Member]
Securities sold under agreements to repurchase	0	0
Municipal Securities [Member] | Maturity Greater than 90 Days [Member]
Securities sold under agreements to repurchase	0	0
Residential Mortgage-backed Securities [Member]
Securities sold under agreements to repurchase	14,085	15,796
Residential Mortgage-backed Securities [Member] | Maturity Overnight and Continuous [Member]
Securities sold under agreements to repurchase	14,085	15,796
Residential Mortgage-backed Securities [Member] | Maturity Less than 30 Days [Member]
Securities sold under agreements to repurchase	0	0
Residential Mortgage-backed Securities [Member] | Maturity 30 to 90 Days [Member]
Securities sold under agreements to repurchase	0	0
Residential Mortgage-backed Securities [Member] | Maturity Greater than 90 Days [Member]
Securities sold under agreements to repurchase	$ 0	$ 0