Fair Value Measurement - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Financial assets
Cash and due from banks	$ 22,039	$ 21,742
Deposits with banks	290,103	321,596
Federal funds sold and securities purchased under resale agreements	482,704	336,426
Investment securities, held-to-maturity	254,513	253,344
Loans, net of allowance for loan losses	62,255	70,684
Financial liabilities
Beneficial interests issued by consolidated VIEs	27,085	27,951
Carrying value
Financial assets
Cash and due from banks	22,000	21,700
Deposits with banks	290,100	321,600
Accrued interest and accounts receivable	141,900	111,100
Federal funds sold and securities purchased under resale agreements	10,200	9,400
Securities borrowed	178,500	188,100
Investment securities, held-to-maturity	272,100	270,100
Loans, net of allowance for loan losses	1,415,300	1,397,000
Other	97,600	93,000
Financial liabilities
Deposits	2,655,700	2,538,400
Federal funds purchased and securities loaned or sold under repurchase agreements	96,500	82,200
Short-term borrowings	39,100	32,300
Accounts payable and other liabilities	300,700	262,600
Beneficial interests issued by consolidated VIEs	27,100	27,900
Long-term debt	304,000	300,600
Wholesale lending-related commitments	3,200	3,200
Total estimated fair value
Financial assets
Cash and due from banks	22,000	21,700
Deposits with banks	290,100	321,600
Accrued interest and accounts receivable	141,900	111,100
Federal funds sold and securities purchased under resale agreements	10,200	9,400
Securities borrowed	178,500	188,100
Investment securities, held-to-maturity	254,500	253,300
Loans, net of allowance for loan losses	1,419,300	1,403,800
Other	97,800	93,200
Financial liabilities
Deposits	2,655,900	2,538,800
Federal funds purchased and securities loaned or sold under repurchase agreements	96,500	82,200
Short-term borrowings	39,100	32,300
Accounts payable and other liabilities	299,700	261,700
Beneficial interests issued by consolidated VIEs	27,100	28,000
Long-term debt	305,900	305,100
Wholesale lending-related commitments	4,200	4,500
Total estimated fair value | Level 1
Financial assets
Cash and due from banks	22,000	21,700
Deposits with banks	290,100	321,600
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	134,400	126,400
Loans, net of allowance for loan losses	0	0
Other	0	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	0
Accrued interest and accounts receivable	141,700	111,000
Federal funds sold and securities purchased under resale agreements	10,200	9,400
Securities borrowed	178,500	188,100
Investment securities, held-to-maturity	120,100	126,900
Loans, net of allowance for loan losses	316,700	314,600
Other	97,200	91,700
Financial liabilities
Deposits	2,655,900	2,538,800
Federal funds purchased and securities loaned or sold under repurchase agreements	96,500	82,200
Short-term borrowings	39,100	32,300
Accounts payable and other liabilities	287,300	248,700
Beneficial interests issued by consolidated VIEs	27,100	28,000
Long-term debt	254,000	253,000
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	200	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	1,102,600	1,089,200
Other	600	1,500
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	12,400	13,000
Beneficial interests issued by consolidated VIEs	0	0
Long-term debt	51,900	52,100
Wholesale lending-related commitments	$ 4,200	$ 4,500