Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) shares in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Days of Delinquent Loans Nonaccrual of Interest			90 days
Minimum Number of Days of Discontinued Loan Payments for Modified Loan to be Placed on Nonaccrual			90 days
Number of Days Past Due			30 days
Threshold for Designation to Impaired Status			$ 250,000
Minimum Number of Days Consumer Loans are Past Due for Losses to be Charged Off			120 days
Maximum Number of Days Consumer Loans are Past Due for Losses to be Charged Off			180 days
Number of Days Loans Secured by Residential Or Commercial Real Estate Are Past Due for Losses to Be Carged Off			180 days
Period of Time Between Issuance of Loan Commitment and Closing and Sale of Loans Lower Range			30 days
Period of Time Between Issuance of Loan Commitments and Closing and Sale of Loans Upper Range			60 days
Noncontrolling Interest, Ownership Percentage by Parent	100.00%		100.00%
Reclassification of Stranded Tax Effects from Change in Tax Rate
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			35.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability	$ 1,560,000		$ 1,560,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			0	0	0
Advertising Expense			$ 148,000	$ 122,000	$ 105,000
Goodwill, Impairment Loss			0	$ 0	$ 0
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%
ASU 2018-02 [Member]
Reclassification of Stranded Tax Effects from Change in Tax Rate			$ 1,718,000
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life			10 years
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life			12 years
Building [Member]
Property, Plant and Equipment, Useful Life			40 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life			3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life			10 years
Computer Equipment [Member]
Property, Plant and Equipment, Useful Life			3 years