v3.25.2
Allowance for expected credit losses - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Allowance for expected credit losses $ 28.8   $ 28.8   $ 28.8
Current expected credit losses $ 0.0 $ (0.4) $ 0.0 $ (0.4)  
Assets within scope of credit losses | Credit concentration risk | AM Best or S&P          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Concentration risk, percentage     61.00%    
Assets within scope of credit losses | Credit concentration risk | AM Best or S&P | AM Best or S&P, rated A- or better          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Concentration risk, percentage     96.00%