Note 10 - Employment Benefit and Retirement Plans (Details Textual)		12 Months Ended
	Sep. 19, 2007	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Oct. 11, 2016 USD ($) $ / shares shares	Jul. 08, 2005 USD ($) $ / shares shares
Loan to Employee Stock Ownership Plan				$ 1,907,160	$ 763,140
Employee Stock Ownership Plan (ESOP), Shares in ESOP | shares		260,660	259,640	190,716	76,314
Sale of Stock, Price Per Share | $ / shares				$ 10	$ 10
Employee Stock Ownership Plan ESOP Interest and Principal Payments from ESOP		$ 239,000
Employee Stock Ownership Plan (ESOP), Number of Committed-to-be-Released Shares | shares		18,779	18,779
Fair Value Per Share | $ / shares		$ 13.68	$ 10.86
Employee Stock Ownership Plan (ESOP), Compensation Expense		$ 256,849	$ 195,949
Employee Stock Ownership Plan (ESOP), Number of Allocated Shares | shares		104,272	85,493
Fair Value Inputs, Discount Rate	4.50%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Safe Harbor Contributions, Percent		3.00%
Defined Contribution Plan, Vesting Period		6 years
Defined Contribution Plan, Employer Discretionary Contribution Amount		$ 173,916	$ 146,920
Deferred Compensation Arrangement with Individual, Contributions by Employer		86,472	85,882
Deferred Compensation Liability, Current and Noncurrent		1,519,993	1,361,190
Supplemental Employee Retirement Plan [Member]
Pension and Other Postretirement Benefits Cost (Reversal of Cost)		97,082	86,365
Supplemental Employee Retirement Plan [Member] | Other Liabilities [Member]
Liability, Defined Benefit Plan		580,896	501,852
Director Retirement Plan [Member]
Liability, Defined Benefit Plan		$ 296,903	$ 315,503
Defined Benefit Plan, Number of Participants		6	6
Defined Benefit Plan, Guaranteed Payment Term		10 years
Director Retirement Plan [Member] | Active Employees Not Yet Eligible [Member]
Defined Benefit Plan, Number of Participants		2	2
Director Retirement Plan [Member] | Other Liabilities [Member]
Liability, Defined Benefit Plan		$ 296,903	$ 315,503
Mezzanine Capital [Member]
Fair Value Per Share | $ / shares		$ 14.44	$ 12.73
Employee Stock Ownership Plan (ESOP), Number of Allocated Shares | shares		83,242	63,443