Fair Value - Carrying Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financial Assets:
Cash and due from banks	$ 3,930	$ 3,970
Interest-bearing deposits with banks	86,048	101,593
Securities purchased under resale agreements	1,668	5,215
Investment securities held-to-maturity	56,863	57,913
Financial Liabilities:
Non-interest-bearing	36,455	46,755
Interest-bearing - U.S.	122,676	111,384
Interest-bearing - non-U.S.	63,185	77,325
Securities sold under repurchase agreements	4,294	1,177
Short-term borrowings	53	2,097
Pricing Methods with Significant Observable Market Inputs (Level 2)
Financial Liabilities:
Net loans (excluding leases)	9	5
Reported Amount
Financial Assets:
Cash and due from banks	3,930	3,970
Interest-bearing deposits with banks	86,048	101,593
Securities purchased under resale agreements	1,668	5,215
Investment securities held-to-maturity	63,510	64,700
Net loans	34,003	32,053
Other	6,326	3,626
Financial Liabilities:
Non-interest-bearing	36,455	46,755
Interest-bearing - U.S.	122,676	111,384
Interest-bearing - non-U.S.	63,185	77,325
Securities sold under repurchase agreements	4,294	1,177
Short-term borrowings	53	2,097
Long-term debt	17,178	14,996
Other	6,326	3,626
Estimated Fair Value
Financial Assets:
Cash and due from banks	3,930	3,970
Interest-bearing deposits with banks	86,048	101,593
Securities purchased under resale agreements	1,668	5,215
Investment securities held-to-maturity	56,863	57,913
Net loans	33,820	31,794
Other	6,326	3,626
Financial Liabilities:
Non-interest-bearing	36,455	46,755
Interest-bearing - U.S.	122,676	111,384
Interest-bearing - non-U.S.	63,185	77,325
Securities sold under repurchase agreements	4,294	1,177
Short-term borrowings	53	2,097
Long-term debt	16,495	14,273
Other	6,326	3,626
Estimated Fair Value | Quoted Market Prices in Active Markets (Level 1)
Financial Assets:
Cash and due from banks	3,930	3,970
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held-to-maturity	11,461	11,336
Net loans	0	0
Other	0	0
Financial Liabilities:
Non-interest-bearing	0	0
Interest-bearing - U.S.	0	0
Interest-bearing - non-U.S.	0	0
Securities sold under repurchase agreements	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Other	0	0
Estimated Fair Value | Pricing Methods with Significant Observable Market Inputs (Level 2)
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	86,048	101,593
Securities purchased under resale agreements	1,668	5,215
Investment securities held-to-maturity	45,402	46,577
Net loans	31,764	29,679
Other	6,326	3,626
Financial Liabilities:
Non-interest-bearing	36,455	46,755
Interest-bearing - U.S.	122,676	111,384
Interest-bearing - non-U.S.	63,185	77,325
Securities sold under repurchase agreements	4,294	1,177
Short-term borrowings	53	2,097
Long-term debt	16,332	14,102
Other	6,326	3,626
Estimated Fair Value | Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held-to-maturity	0	0
Net loans	2,056	2,115
Other	0	0
Financial Liabilities:
Non-interest-bearing	0	0
Interest-bearing - U.S.	0	0
Interest-bearing - non-U.S.	0	0
Securities sold under repurchase agreements	0	0
Short-term borrowings	0	0
Long-term debt	163	171
Other	$ 0	$ 0