Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments - Standby Letters of Credit and Other Financial Guarantees (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Standby letters of credit and other financial guarantees and other letters of credit [Abstract]
Total lending-related commitments	$ 1,714,006	$ 1,577,622
Allowance for lending-related commitments	2,964	2,101	$ 2,142	$ 1,974
Total carrying value	4,231	3,689
Standby letters of credit and other financial guarantees
Standby letters of credit and other financial guarantees and other letters of credit [Abstract]
Investment-grade	19,924	20,443
Noninvestment-grade	8,968	8,233
Total lending-related commitments	28,892	28,676
Allowance for lending-related commitments	175	94
Guarantee liability	426	379
Total carrying value	601	473
Commitments with collateral	16,523	16,805
Other letters of credit
Standby letters of credit and other financial guarantees and other letters of credit [Abstract]
Investment-grade	2,889	3,380
Noninvestment-grade	1,123	974
Total lending-related commitments	4,012	4,354
Allowance for lending-related commitments	12	37
Guarantee liability	0	0
Total carrying value	12	37
Commitments with collateral	$ 565	$ 357