Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parentheticals) $ in Thousands	9 Months Ended
Sep. 30, 2019 USD ($)
May 2019 Public Offering [Member]
Common stock issued during period, offering costs	$ 739
January 2019 Public Offering [Member]
Common stock issued during period, offering costs	$ 1,683

The cash outflow for cost incurred directly with the issuance of an equity security.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

Name:	us-gaap_PaymentsOfStockIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration