Fair value measurements - Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Trade claims
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$ 2,684
Total realized and unrealized gain (losses)		0
Purchases and issuances		534
Sales and settlements		0
Transfers in (out)		0
Ending balance		3,218
Corporate debt and other obligations | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 1,170
Total realized and unrealized gain (losses)	0
Purchases and issuances	0
Sales and settlements	0
Transfers in (out)	0
Ending balance	1,170
Corporate equities | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	2,064
Total realized and unrealized gain (losses)	89
Purchases and issuances	0
Sales and settlements	0
Transfers in (out)	0
Ending balance	2,153
Private equity securities | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	17,000
Total realized and unrealized gain (losses)	0
Purchases and issuances	0
Sales and settlements	0
Transfers in (out)	0
Ending balance	17,000
Other debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		2,652
Total realized and unrealized gain (losses)		206
Purchases and issuances		0
Sales and settlements		(2,730)
Transfers in (out)		0
Ending balance	128	$ 128
Other debt securities | Fair Value, Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	128
Total realized and unrealized gain (losses)	0
Purchases and issuances	0
Sales and settlements	0
Transfers in (out)	$ 0