Fair value measurements - Schedule of Gains Losses From Credit Risks (Details) - Insurance Solutions - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, option, changes in fair value, gain (loss)	$ 52	$ (22)
Corporate loans
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, option, changes in fair value, gain (loss)	18	368
Other invested assets
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, option, changes in fair value, gain (loss)	34	(390)
Variable Interest Entity, Primary Beneficiary
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, option, changes in fair value, gain (loss)	(255)	(247)
Consolidated Balance Including Variable Interest Entity
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, option, changes in fair value, gain (loss)	$ (203)	$ (269)