v3.26.1
Securities - Gross Unrealized Losses and Related Fair Values (Detail) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Securities available-for-sale gross unrealized losses one year or less $ (31) $ (1)
Securities available-for-sale aggregate fair value of investment one year or less 8,245 1,720
Securities available-for-sale gross unrealized losses greater than one year (1,732) (1,676)
Securities available-for-sale aggregate fair value of investment greater than one year 12,622 13,409
U.S. Treasury    
Debt Securities, Available-for-sale [Line Items]    
Securities available-for-sale gross unrealized losses one year or less (21) 0
Securities available-for-sale aggregate fair value of investment one year or less 4,540 0
Securities available-for-sale gross unrealized losses greater than one year (124) (107)
Securities available-for-sale aggregate fair value of investment greater than one year 3,148 3,419
U.S. Government sponsored enterprises    
Debt Securities, Available-for-sale [Line Items]    
Securities available-for-sale gross unrealized losses one year or less 0 0
Securities available-for-sale aggregate fair value of investment one year or less 0 0
Securities available-for-sale gross unrealized losses greater than one year (805) (808)
Securities available-for-sale aggregate fair value of investment greater than one year 3,422 3,592
U.S. Government agency issued or guaranteed    
Debt Securities, Available-for-sale [Line Items]    
Securities available-for-sale gross unrealized losses one year or less (9) 0
Securities available-for-sale aggregate fair value of investment one year or less 2,080 50
Securities available-for-sale gross unrealized losses greater than one year (795) (752)
Securities available-for-sale aggregate fair value of investment greater than one year 5,949 6,313
Asset-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Securities available-for-sale gross unrealized losses one year or less 0 0
Securities available-for-sale aggregate fair value of investment one year or less 0 129
Securities available-for-sale gross unrealized losses greater than one year (8) (9)
Securities available-for-sale aggregate fair value of investment greater than one year 103 85
Foreign debt securities    
Debt Securities, Available-for-sale [Line Items]    
Securities available-for-sale gross unrealized losses one year or less (1) (1)
Securities available-for-sale aggregate fair value of investment one year or less 1,625 1,541
Securities available-for-sale gross unrealized losses greater than one year 0 0
Securities available-for-sale aggregate fair value of investment greater than one year $ 0 $ 0