Note 9 - Allowance for Loan Losses and Credit Quality Information (Details) - Purchased Credit Impaired Loans Acquired Through Kasson State Bank Acquisition - Kasson State Bank [Member] $ in Thousands	2 Months Ended
	Sep. 30, 2015 USD ($)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Balance at August 15, 2015:	$ 1,134
Balance at August 15, 2015:	(497)
Balance at August 15, 2015:	637
Balance at September 30, 2015	1,118
Balance at September 30, 2015	(497)
Balance at September 30, 2015	621
Change due to payments/refinances	(16)
Change due to payments/refinances	0
Change due to payments/refinances	(16)
Transferred to foreclosed assets	0
Transferred to foreclosed assets	0
Transferred to foreclosed assets	0
Change due to loan charge-off	0
Change due to loan charge-off	0
Change due to loan charge-off	$ 0