Digital assets - Narrative (Details) $ in Millions	Sep. 30, 2026 USD ($)
Intangible Asset, Goodwill and Other [Abstract]
Digital assets fair value amount	$ 2.7

Fair value of crypto asset subject to contractual sale restriction. Excludes crypto asset held for platform user.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476162/350-60-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476162/350-60-50-6

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