Note 6 - Securities Sold Under Agreements to Repurchase (Details) - Securities Sold Under Agreement to Repurchase - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Securities Sold Under Agreement to Repurchase [Abstract]
Outstanding balance at end of period	$ 158,149,000	$ 167,569,000
Average interest rate at end of period	0.11%	0.11%
Average daily balance during the period	$ 145,867,000	$ 105,474,000
Average interest rate during the period	0.11%	0.12%
Maximum daily balance during the period	$ 168,211,000	$ 178,042,000