Note 7 - Income Taxes - Provision for Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current provision:
Federal	$ 1,607,117	$ 3,090,997	$ 3,108,894
State	223,749	309,249	486,565
Total current income tax expense	1,830,866	3,400,246	3,595,459
Deferred provision (benefit):
Federal	(76,438)	(665,181)	183,520
State	(14,559)	(23,692)	21,591
Total deferred income tax expense	(90,997)	(688,873)	205,111
Total income tax expense	$ 1,739,869	$ 2,711,373	$ 3,800,570