Fair value measurements - Evernorth - Interim (Details) - USD ($) |
Jun. 30, 2026 |
Dec. 31, 2025 |
Sep. 30, 2025 |
|---|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Refundable investor advances | $ 687,093,995 | $ 764,570,995 | $ 0 |
| Total financial liabilities | 687,093,995 | 764,570,995 | |
| Level 1 | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Refundable investor advances | 0 | 0 | |
| Total financial liabilities | 0 | 0 | |
| Level 2 | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Refundable investor advances | 0 | 0 | |
| Total financial liabilities | 0 | 0 | |
| Level 3 | |||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
| Refundable investor advances | 687,093,995 | 764,570,995 | |
| Total financial liabilities | $ 687,093,995 | $ 764,570,995 |