v3.26.3
Commitments and Contingencies (Details) - Standby Letters of Credit - Line of Credit
$ in Millions
 9 Months Ended
Sep. 30, 2026
USD ($)
Line of Credit Facility [Line Items]  
Commitment $ 340.0
In Use 97.0
Letters of credit outstanding, amount $ 105.5
Minimum  
Line of Credit Facility [Line Items]  
Debt instrument, term 1 year
Maximum  
Line of Credit Facility [Line Items]  
Debt instrument, term 3 years
Lloyds Bank plc  
Line of Credit Facility [Line Items]  
Commitment $ 135.0
In Use 36.8
Letters of credit outstanding, amount 42.5
Citibank N.A. London branch  
Line of Credit Facility [Line Items]  
Commitment 70.0
In Use 14.2
Letters of credit outstanding, amount 15.9
Barclays Bank plc  
Line of Credit Facility [Line Items]  
Commitment 135.0
In Use 44.1
Letters of credit outstanding, amount 44.4
Bank of Montreal  
Line of Credit Facility [Line Items]  
Commitment 0.0
In Use 1.9
Letters of credit outstanding, amount 2.7
Unsecured | Lloyds Bank plc  
Line of Credit Facility [Line Items]  
Commitment 20.0
In Use 2.9
Unsecured | Barclays Bank plc  
Line of Credit Facility [Line Items]  
Commitment 20.0
In Use 6.7
Secured | Lloyds Bank plc  
Line of Credit Facility [Line Items]  
Commitment 115.0
In Use 33.9
Secured | Citibank N.A. London branch  
Line of Credit Facility [Line Items]  
Commitment 70.0
In Use 14.2
Secured | Barclays Bank plc  
Line of Credit Facility [Line Items]  
Commitment 115.0
In Use 37.4
Secured | Bank of Montreal  
Line of Credit Facility [Line Items]  
Commitment 0.0
In Use 1.9
Uncommitted Tranche | Lloyds Bank plc  
Line of Credit Facility [Line Items]  
Commitment 65.0
Uncommitted Tranche | Citibank N.A. London branch  
Line of Credit Facility [Line Items]  
Commitment 200.0
Ancillary own funds | Barclays Bank plc  
Line of Credit Facility [Line Items]  
Commitment $ 65.0