v3.26.1
Fair value measurements - Schedule of Realized and Unrealized Gains From Investments (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments $ (3,386) $ 226
Unrealized gain/(loss) on investments 11,776 (8,449)
Asset Management    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments 418 338
Unrealized gain/(loss) on investments 1,603 (1,869)
Net gains (losses) from investment activities 2,021 (1,531)
Asset Management | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Unrealized gain/(loss) on investments 1,339 (296)
Net gains (losses) from investment activities 1,339 (296)
Asset Management | Debt obligation | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Unrealized gain/(loss) on investments 1,339 (296)
Net gains (losses) from investment activities 1,339 (296)
Insurance Solutions | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (2,869) 133
Unrealized gain/(loss) on investments 11,197 (4,546)
Net gains (losses) from investment activities 8,328 (4,413)
Insurance Solutions | Variable Interest Entity, Primary Beneficiary    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (386) 107
Unrealized gain/(loss) on investments (2,015) (3,177)
Net gains (losses) from investment activities (2,401) (3,070)
Insurance Solutions | Variable Interest Entity, Primary Beneficiary | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (386) 107
Unrealized gain/(loss) on investments (2,015) (3,177)
Net gains (losses) from investment activities (2,401) (3,070)
Insurance Solutions | Consolidated Balance Including Variable Interest Entity    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (3,809) (112)
Unrealized gain/(loss) on investments 11,549 (6,938)
Net gains (losses) from investment activities 3,816 (11,281)
Insurance Solutions | Consolidated Balance Including Variable Interest Entity | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (3,255) 240
Unrealized gain/(loss) on investments 9,182 (7,723)
Net gains (losses) from investment activities 5,927 (7,483)
Insurance Solutions | Corporate    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (1,773) (165)
Unrealized gain/(loss) on investments 5,023 (3,710)
Net gains (losses) from investment activities 3,250 (3,875)
Insurance Solutions | Corporate | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (1,815)  
Unrealized gain/(loss) on investments 5,023 (3,710)
Net gains (losses) from investment activities 3,208 (3,710)
Insurance Solutions | U.S. state, territories and municipalities | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Unrealized gain/(loss) on investments 51 (10)
Net gains (losses) from investment activities 51 (10)
Insurance Solutions | Other government and agency    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments 0 0
Unrealized gain/(loss) on investments 115 (18)
Net gains (losses) from investment activities 115 (18)
Insurance Solutions | Other government and agency | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Unrealized gain/(loss) on investments 115 (18)
Net gains (losses) from investment activities 115 (18)
Insurance Solutions | Asset and mortgage-backed securities    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (641) (158)
Unrealized gain/(loss) on investments 117 4,041
Net gains (losses) from investment activities (524) 3,883
Insurance Solutions | Asset and mortgage-backed securities | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (295) 21
Unrealized gain/(loss) on investments 117 4,041
Net gains (losses) from investment activities (178) 4,062
Insurance Solutions | Corporate loans    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (4) 110
Unrealized gain/(loss) on investments 1,853 (594)
Net gains (losses) from investment activities 1,849 (484)
Insurance Solutions | Corporate loans | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (4) 110
Unrealized gain/(loss) on investments 1,853 (594)
Net gains (losses) from investment activities 1,849 (484)
Insurance Solutions | Other invested assets | Fair value option    
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Realized gain/(loss) on investments (755) 2
Unrealized gain/(loss) on investments 4,038 (4,255)
Net gains (losses) from investment activities $ 3,283 $ (4,253)