Subsequent events (Details) - 1 months ended Oct. 31, 2021 - Subsequent event	USD ($)	EUR (€)
Subsequent Event [Line Items]
Issued amount of debt	$ 1,200,000	€ 1,000,000
Debt instrument, term	6 years

Face (par) amount of debt instrument at time of issuance.

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