Note 9 - Earnings Per Share (Details Textual)	3 Months Ended
Mar. 31, 2021
Earnings Per Share [Abstract]
Common stock conversion basis	one-for-one basis

Description of basis for conversion of convertible common stock.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_CommonStockConversionBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration