v3.25.2
Commitments and Contingencies - Narrative (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Loss Contingencies [Line Items]    
Pledged Collateral $ 1,510 $ 1,238
Loss Contingency, Range of Possible Loss, Portion Not Accrued 0  
Acquisition of mortgage loans    
Loss Contingencies [Line Items]    
Amount of purchase commitment 158  
Purchase of limited partnerships and private placement investments    
Loss Contingencies [Line Items]    
Amount of purchase commitment 1,697  
Federal Home Loan Bank of Boston | Line of Credit    
Loss Contingencies [Line Items]    
Non-putable funding agreements issued to FHLB $ 872 $ 721