Note 8 - Securities Sold Under Agreements to Repurchase (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2007
Securities Sold under Agreements to Repurchase	$ 34,252	$ 36,370
Long-term Repurchase Agreements, Leverage Transaction [Member]
Securities Sold under Agreements to Repurchase			$ 100,000	$ 200,000
Assets Sold under Agreements to Repurchase, Interest Rate				3.95%