Note 3 - Cash and Cash Equivalents (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Average Reserve Balances Required to be Maintained with Federal Bank	$ 1,900,000	$ 138,000
Average Excess Balances Maintained With Federal Reserve Bank	338,500,000	$ 163,300,000
Margin Deposit Assets	$ 6,900,000