Note 8 - Short-Term Borrowings (Details) - Overnight Repurchase Agreements (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Securities underlying the agreements as of end of period:
Carrying value	$ 165,360,426	$ 143,262,002
Fair value	165,360,426	143,262,002
Repurchase Agreements With Customers [Member]
Note 8 - Short-Term Borrowings (Details) - Overnight Repurchase Agreements [Line Items]
Average daily balance during the period	128,818,152	123,543,416
Average daily interest rate during the period	0.12%	0.12%
Maximum month-end balance during the period	147,623,624	146,075,177
Weighted average rate as of end of period	0.13%	0.13%
Federal Funds Purchased [Member]
Note 8 - Short-Term Borrowings (Details) - Overnight Repurchase Agreements [Line Items]
Average daily balance during the period	33,876,815	41,156,729
Average daily interest rate during the period	0.40%	0.40%
Maximum month-end balance during the period	$ 131,100,000	$ 95,380,000
Weighted average rate as of end of period	0.23%	0.28%