v3.26.3
Debt and letter of credit facilities - Narrative (Details) - USD ($)
3 Months Ended 9 Months Ended
Sep. 25, 2025
Dec. 19, 2024
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Jun. 30, 2026
Debt Instrument [Line Items]              
Interest expense     $ 11,700,000 $ 12,100,000 $ 35,100,000 $ 35,900,000  
Funds withheld     5,100,000 $ 7,200,000 15,900,000 $ 23,700,000  
Federal home loan bank, borrowing limit, percentage of admitted assets 5.00%            
Federal home loan bank advances general debt obligations disclosures admitted assets             $ 3,500,000,000
Advances or repayments of FHLBNY borrowings     0   0    
Advances outstanding     0   0    
Revolving Credit Facility              
Debt Instrument [Line Items]              
Contractual term   4 years          
Maximum borrowing capacity   $ 400,000,000.0          
Outstanding borrowings     $ 0   $ 0