v3.26.1
Commitments and Contingencies (Details) - Standby Letters of Credit - Line of Credit
$ in Millions
 6 Months Ended
Jun. 30, 2026
USD ($)
Line of Credit Facility [Line Items]  
Commitment $ 480.0
In Use 111.7
Letters of credit outstanding, amount $ 112.1
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 27.8
Letters of credit outstanding, amount 28.9
Citibank N.A. London branch  
Line of Credit Facility [Line Items]  
Commitment 70.0
In Use 14.1
Letters of credit outstanding, amount 17.6
Barclays Bank plc  
Line of Credit Facility [Line Items]  
Commitment 135.0
In Use 39.1
Letters of credit outstanding, amount 32.7
Bank of Montreal  
Line of Credit Facility [Line Items]  
Commitment 140.0
In Use 30.7
Letters of credit outstanding, amount 32.9
Unsecured | Lloyds Bank plc  
Line of Credit Facility [Line Items]  
Commitment 20.0
In Use 4.4
Unsecured | Barclays Bank plc  
Line of Credit Facility [Line Items]  
Commitment 20.0
In Use 9.3
Unsecured | Bank of Montreal  
Line of Credit Facility [Line Items]  
Commitment 40.0
In Use 4.6
Secured | Lloyds Bank plc  
Line of Credit Facility [Line Items]  
Commitment 115.0
In Use 23.4
Secured | Citibank N.A. London branch  
Line of Credit Facility [Line Items]  
Commitment 70.0
In Use 14.1
Secured | Barclays Bank plc  
Line of Credit Facility [Line Items]  
Commitment 115.0
In Use 29.8
Secured | Bank of Montreal  
Line of Credit Facility [Line Items]  
Commitment 100.0
In Use 26.1
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
Ancillary own funds | Bank of Montreal  
Line of Credit Facility [Line Items]  
Commitment $ 60.0