Note 4 - Loans and Allowance for Loan Losses (Details Textual) xbrli-pure in Thousands	3 Months Ended
Mar. 31, 2018 USD ($)	Mar. 31, 2017	Dec. 31, 2017 USD ($)
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Troubled Debt Restructuring [Member]
Allowance for Credit Losses, Change in Method of Calculating Impairment	$ 976,551		$ 372,321

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration