Note 10 - Income Taxes - The Provision (Credit) for Income Taxes (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Taxes currently payable									$ 1,889,673	$ 2,140,591	$ 1,445,947
Deferred income taxes									123,091	320,738	657,573
	$ 514,981	$ 554,009	$ 416,399	$ 527,375	$ 554,983	$ 621,751	$ 696,158	$ 588,437	$ 2,012,764	$ 2,461,329	$ 2,112,508