Commitments and contingencies (Details) - USD ($)	6 Months Ended	12 Months Ended
Jun. 30, 2025	Dec. 31, 2024
Commitments and contingencies.
Provision for contingent losses	$ 0	$ 0

Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483076/450-20-50-1

Name:	us-gaap_LossContingencyAccrualProvision
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration