Note 10 - Securities Sold Under Agreements to Repurchase and Other Short-term Borrowings - Securities Sold Under Agreements to Repurchase (Details) - Securities Sold under Agreements to Repurchase [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Average balance during the year	$ 70,187	$ 62,670
Average interest rate during the year	0.19%	0.22%
Maximum month-end balance during the year	$ 75,365	$ 72,029