Fair value of assets and liabilities - Narrative (Details) $ in Millions |
9 Months Ended | |
|---|---|---|
|
Sep. 30, 2026
USD ($)
litigation_event
litigation_type
|
Dec. 31, 2025
USD ($)
|
|
| Fair Value Disclosures [Abstract] | ||
| Number of litigation events | litigation_event | 70 | |
| Number of litigation types | litigation_type | 5 | |
| Percentage of discrete objective litigation events | 10.00% | |
| Increase in income and net assets due to decrease in interest rate | $ | $ 335.5 | $ 491.1 |