Note 5 - Earnings Per Share (Details Textual) - shares	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Weighted Average Number Diluted Shares Outstanding Adjustment, Total	20,153	36,801

The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration