Investment securities (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Current investments:
Amortized cost	$ 123,196	$ 208,591
Gross unrealized holding gains	168	164
Estimated fair value	123,364	208,755
Investment securities with original maturities of less than 90 days when purchased and presented within cash and cash equivalents at amortized cost	109,000	15,300
Government debt securities (held-to-maturity)
Current investments:
Amortized cost	123,196	208,591
Gross unrealized holding gains	168	164
Estimated fair value	$ 123,364	$ 208,755

Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity), classified as current.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-5

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481830/320-10-45-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481830/320-10-45-1

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