Fair Value Measurement - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financial assets
Cash and due from banks	$ 21,821	$ 23,372
Deposits with banks	281,615	445,945
Federal funds sold and securities purchased under resale agreements	425,815	295,001
Investment securities, held-to-maturity	274,905	247,900
Loans, net of allowance for loan losses	54,686	41,350
Financial liabilities
Beneficial interests issued by consolidated VIEs	28,227	27,323
Carrying value
Financial assets
Cash and due from banks	21,800	23,400
Deposits with banks	281,600	445,900
Accrued interest and accounts receivable	141,500	101,100
Federal funds sold and securities purchased under resale agreements	21,200	8,200
Securities borrowed	143,600	135,600
Investment securities, held-to-maturity	293,400	274,500
Loans, net of allowance for loan losses	1,354,800	1,282,300
Other	91,400	82,700
Financial liabilities
Deposits	2,512,500	2,372,300
Federal funds purchased and securities loaned or sold under repurchase agreements	78,400	70,500
Short-term borrowings	32,700	26,400
Accounts payable and other liabilities	266,900	232,800
Beneficial interests issued by consolidated VIEs	28,200	27,300
Long-term debt	303,000	300,600
Wholesale lending-related commitments	3,400	2,700
Total estimated fair value
Financial assets
Cash and due from banks	21,800	23,400
Deposits with banks	281,600	445,900
Accrued interest and accounts receivable	141,500	101,100
Federal funds sold and securities purchased under resale agreements	21,200	8,200
Securities borrowed	143,600	135,600
Investment securities, held-to-maturity	274,900	247,900
Loans, net of allowance for loan losses	1,357,600	1,276,500
Other	91,600	82,900
Financial liabilities
Deposits	2,512,800	2,372,500
Federal funds purchased and securities loaned or sold under repurchase agreements	78,400	70,500
Short-term borrowings	32,700	26,300
Accounts payable and other liabilities	266,100	232,200
Beneficial interests issued by consolidated VIEs	28,300	27,400
Long-term debt	307,000	301,900
Wholesale lending-related commitments	4,700	4,400
Total estimated fair value | Level 1
Financial assets
Cash and due from banks	21,800	23,400
Deposits with banks	281,600	445,800
Accrued interest and accounts receivable	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Securities borrowed	0	0
Investment securities, held-to-maturity	141,700	97,400
Loans, net of allowance for loan losses	0	0
Other	500	0
Financial liabilities
Deposits	0	0
Federal funds purchased and securities loaned or sold under repurchase agreements	0	0
Short-term borrowings	0	0
Accounts payable and other liabilities	0	0
Beneficial interests issued by consolidated VIEs	0	0
Long-term debt	0	0
Wholesale lending-related commitments	0	0
Total estimated fair value | Level 2
Financial assets
Cash and due from banks	0	0
Deposits with banks	0	100
Accrued interest and accounts receivable	141,400	101,000
Federal funds sold and securities purchased under resale agreements	21,200	8,200
Securities borrowed	143,600	135,600
Investment securities, held-to-maturity	133,200	150,500
Loans, net of allowance for loan losses	246,100	268,700
Other	89,600	81,300
Financial liabilities
Deposits	2,512,800	2,372,500
Federal funds purchased and securities loaned or sold under repurchase agreements	78,400	70,500
Short-term borrowings	32,700	26,300
Accounts payable and other liabilities	254,000	219,600
Beneficial interests issued by consolidated VIEs	28,300	27,400
Long-term debt	254,900	251,200
Wholesale lending-related commitments	0	0
Total estimated fair value | Level 3
Financial assets
Cash and due from banks	0	0
Deposits with banks	0	0
Accrued interest and accounts receivable	100	100
Federal funds sold and securities purchased under resale agreements	0	0
Securities borrowed	0	0
Investment securities, held-to-maturity	0	0
Loans, net of allowance for loan losses	1,111,500	1,007,800
Other	1,500	1,600
Financial liabilities
Deposits	0	0
Federal funds purchased and securities loaned or sold under repurchase agreements	0	0
Short-term borrowings	0	0
Accounts payable and other liabilities	12,100	12,600
Beneficial interests issued by consolidated VIEs	0	0
Long-term debt	52,100	50,700
Wholesale lending-related commitments	$ 4,700	$ 4,400