Balance sheet components - Other non-current assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Convertible note receivable	$ 3,081	$ 3,021
Other non-current assets	3,821	4,653
Other non-current assets	$ 6,902	$ 7,674

Amount of noncurrent assets classified as other.

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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_OtherAssetsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant