Note 13 - Earnings Per Common Share - Summary of Earnings Per Share Calculation (Details) - USD ($)	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2017
Income (Loss) available to common stockholders					$ 510,262				$ (313,706)	$ 3,613,710	$ 1,408,396
Weighted Average Shares of Common Stock Outstanding (in shares)					2,888,502				2,853,107	2,799,706	2,874,926
Net Income Per Common Share - Basic (in dollars per share)	$ 0.50	$ 0.55	$ 0.14	$ 0.13	$ 0.18	$ 0.20	$ 0.33	$ 0.07	$ (0.11)	$ 1.29	$ 0.49
Options and warrants under convertible note (in shares)					367,510				48,477	376,773	194,151
Weighted Average Shares of Common Stock Outstanding - Diluted (in shares)					3,256,012				2,901,584	3,181,572	3,069,077
Income (Loss) available to common stockholders					$ 510,262				$ (313,706)	$ 3,613,710	$ 1,408,396
Weighted Average Shares of Common Stock Outstanding - Diluted (in shares)					3,256,012				2,901,584	3,181,572	3,069,077
Net Income Per Common Share - Diluted (in dollars per share)	$ 0.43	$ 0.48	$ 0.13	$ 0.11	$ 0.16	$ 0.18	$ 0.31	$ 0.07	$ (0.11)	$ 1.14	$ 0.46