v3.26.3
Accumulated Other Comprehensive Income (Changes In The Components Of AOCI) (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     $ (2,237)  
Other comprehensive income (loss) $ (42) $ 7 (47) $ 39
Ending balance (2,391)   (2,391)  
Location, Statement of Other Comprehensive Income, Balance [Axis]: us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     (95)  
Other comprehensive income (loss)     (47)  
Ending balance (142)   (142)  
Unrealized gains (losses) on AFS, net [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     (114)  
Other comprehensive income (loss)     (45)  
Ending balance (159)   (159)  
Instrument-specific credit risk of liabilities measured at fair value, net [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     19  
Other comprehensive income (loss)     (2)  
Ending balance 17   17  
Instrument-specific credit risk of liabilities measured at fair value, net [Member] | Location, Statement of Other Comprehensive Income, Balance [Axis]: us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     19  
Ending balance $ 17   $ 17