Note 1 - Basis of Presentation - Additional Information - (Details Textual)	9 Months Ended
Sep. 30, 2019 Segment	Aug. 07, 2019 $ / shares
Basis of Presentation [Line Items]
Number of reportable segments \| Segment	3
Merger Agreement [Member]
Basis of Presentation [Line Items]
Merger agreement transaction average share price \| $ / shares		$ 60.00

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

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