v3.26.1
Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Credit Ratings of Credit Risk Related Guarantees (Detail) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss $ 8,109 $ 9,425
Total, Notional/Maximum Exposure to Loss 18,848 15,865
Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss $ 7,910 $ 6,560
Single name credit default swaps | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Average Life (in years) 1 year  
Credit derivatives, Notional/Maximum Exposure to Loss $ 1,552  
Index credit derivatives | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Average Life (in years) 4 years 4 months 24 days  
Credit derivatives, Notional/Maximum Exposure to Loss $ 6,358  
Standby Letters of Credit    
Credit Derivatives [Line Items]    
Average Life (in years) 9 months 18 days  
Standby letters of credit, Notional/Maximum Exposure to Loss $ 10,938  
Investment Grade    
Credit Derivatives [Line Items]    
Total, Notional/Maximum Exposure to Loss 14,974  
Investment Grade | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss 6,917  
Investment Grade | Single name credit default swaps | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss 1,204  
Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss 5,713  
Investment Grade | Standby Letters of Credit    
Credit Derivatives [Line Items]    
Standby letters of credit, Notional/Maximum Exposure to Loss 8,057  
Non-Investment Grade    
Credit Derivatives [Line Items]    
Total, Notional/Maximum Exposure to Loss 3,874  
Non-Investment Grade | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss 993  
Non-Investment Grade | Single name credit default swaps | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss 348  
Non-Investment Grade | Index credit derivatives | Sell-protection Credit Derivatives    
Credit Derivatives [Line Items]    
Credit derivatives, Notional/Maximum Exposure to Loss 645  
Non-Investment Grade | Standby Letters of Credit    
Credit Derivatives [Line Items]    
Standby letters of credit, Notional/Maximum Exposure to Loss $ 2,881