Note 7 - Fair Values of Financial Instruments (Details Textual)	Mar. 31, 2018	Dec. 31, 2017
Measurement Input, Pull-through Rate [Member] \| Weighted Average [Member] \| Interest Rate Lock Commitments [Member]
Derivative Asset, Measurement Input	81	77

Value of input used to measure derivative asset.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Name:	us-gaap_DerivativeAssetMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant