v3.25.2
Investment securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
AFS, less than 12 months, fair value $ 1,841 $ 8,966
AFS, less than 12 months, gross unrealized losses 11 107
AFS, 12 months or longer, fair value 2,577 4,243
AFS, 12 months or longer, gross unrealized losses 85 132
Total investment securities, less than 12 months, fair value 2,575 10,051
Total investment securities, less than 12 months, gross unrealized losses 15 127
Total investment securities, 12 months or longer, fair value 13,478 16,013
Total investment securities, 12 months or longer, gross unrealized losses 1,045 1,361
Schedule of Held-to-Maturity Securities [Line Items]    
HTM, less than 12 months, fair value 734 1,085
HTM, Less than 12 months, gross unrealized losses 4 20
HTM, 12 months or longer, fair value 10,901 11,770
HTM, 12 months or longer, gross unrealized losses 960 1,229
U.S. Treasury    
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
AFS, less than 12 months, fair value 523 1,971
AFS, less than 12 months, gross unrealized losses 1 9
AFS, 12 months or longer, fair value 1,119 2,554
AFS, 12 months or longer, gross unrealized losses 5 18
Schedule of Held-to-Maturity Securities [Line Items]    
HTM, less than 12 months, fair value 50 50
HTM, Less than 12 months, gross unrealized losses 0 0
HTM, 12 months or longer, fair value 385 951
HTM, 12 months or longer, gross unrealized losses 8 14
Commercial    
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
AFS, less than 12 months, fair value 624 2,566
AFS, less than 12 months, gross unrealized losses 4 45
AFS, 12 months or longer, fair value 0 64
AFS, 12 months or longer, gross unrealized losses 0 0
Schedule of Held-to-Maturity Securities [Line Items]    
HTM, less than 12 months, fair value 0 0
HTM, Less than 12 months, gross unrealized losses 0 0
HTM, 12 months or longer, fair value 1,925 1,877
HTM, 12 months or longer, gross unrealized losses 94 157
Residential    
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
AFS, less than 12 months, fair value 693 4,429
AFS, less than 12 months, gross unrealized losses 6 53
AFS, 12 months or longer, fair value 1,457 1,623
AFS, 12 months or longer, gross unrealized losses 80 114
Schedule of Held-to-Maturity Securities [Line Items]    
HTM, less than 12 months, fair value 649 996
HTM, Less than 12 months, gross unrealized losses 4 19
HTM, 12 months or longer, fair value 6,591 6,811
HTM, 12 months or longer, gross unrealized losses 756 942
Other    
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]    
AFS, less than 12 months, fair value 1 0
AFS, less than 12 months, gross unrealized losses 0 0
AFS, 12 months or longer, fair value 1 2
AFS, 12 months or longer, gross unrealized losses 0 0
State and political subdivisions    
Schedule of Held-to-Maturity Securities [Line Items]    
HTM, less than 12 months, fair value 35 39
HTM, Less than 12 months, gross unrealized losses 0 1
HTM, 12 months or longer, fair value 2,000 2,131
HTM, 12 months or longer, gross unrealized losses $ 102 $ 116