Certain transactions (Other transactions) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Sep. 30, 2019	Apr. 30, 2018	Apr. 30, 2014
Certain transactions
Warrants granted			6,401
Exercise price of warrants			$ 4.88
Line of credit maximum borrowing capacity		$ 30,000	$ 5,000
Exercise of warrants	5,166

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant