Note 15 - Parent Company Financial Information - Statements of Income (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, 2018	Dec. 31, 2017
Interest income:
Total income	$ 4,599,891	$ 4,525,190	$ 4,385,506	$ 4,257,746	$ 4,264,414	$ 4,232,017	$ 4,121,760	$ 3,976,612	$ 17,768,333	$ 16,594,803
Noninterest expense									10,332,480	10,023,102
Income before before income taxes and equity in undistributed income of subsidiaries									5,818,885	5,791,555
Income taxes (benefit)									1,106,209	2,002,314
	$ 1,136,805	$ 1,308,688	$ 1,145,065	$ 1,122,118	$ 656,339	$ 1,014,456	$ 1,134,889	$ 983,557	4,712,676	3,789,241
Parent Company [Member]
Interest income:
Cash dividends from subsidiary									1,541,225	1,250,278
Total income									1,541,225	1,250,278
Noninterest expense									492	455
Income before before income taxes and equity in undistributed income of subsidiaries									1,540,733	1,249,823
Income taxes (benefit)
Income before before equity in undistributed income of subsidiaries									1,540,733	1,249,823
Equity in undistributed income of subsidiaries									3,171,943	2,539,418
									$ 4,712,676	$ 3,789,241