Fair Value - Carrying Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financial Assets:
Cash and due from banks	$ 3,515	$ 3,631
Interest-bearing deposits with banks	91,360	106,358
Securities purchased under resale agreements	5,203	3,012
Investment securities held-to-maturity	60,103	42,271
Financial Liabilities:
Non-interest-bearing	55,062	56,461
Interest-bearing - U.S.	107,262	102,985
Interest-bearing - non-U.S.	79,589	95,589
Securities sold under repurchase agreements	951	1,575
Other short-term borrowings	73	128
Pricing Methods with Significant Observable Market Inputs (Level 2)
Financial Liabilities:
Net loans (excluding leases)	155	8
Reported Amount
Financial Assets:
Cash and due from banks	3,515	3,631
Interest-bearing deposits with banks	91,360	106,358
Securities purchased under resale agreements	5,203	3,012
Investment securities held-to-maturity	64,261	42,430
Net loans	33,470	32,445
Other	1	1
Financial Liabilities:
Non-interest-bearing	55,062	56,461
Interest-bearing - U.S.	107,262	102,985
Interest-bearing - non-U.S.	79,589	95,589
Securities sold under repurchase agreements	951	1,575
Other short-term borrowings	73	128
Long-term debt	13,530	13,475
Other	1	1
Estimated Fair Value
Financial Assets:
Cash and due from banks	3,515	3,631
Interest-bearing deposits with banks	91,360	106,358
Securities purchased under resale agreements	5,203	3,012
Investment securities held-to-maturity	60,103	42,271
Net loans	33,209	32,528
Other	1	1
Financial Liabilities:
Non-interest-bearing	55,062	56,461
Interest-bearing - U.S.	107,262	102,985
Interest-bearing - non-U.S.	79,589	95,589
Securities sold under repurchase agreements	951	1,575
Other short-term borrowings	73	128
Long-term debt	12,771	13,552
Other	1	1
Estimated Fair Value | Quoted Market Prices in Active Markets (Level 1)
Financial Assets:
Cash and due from banks	3,515	3,631
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held-to-maturity	11,331	2,160
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
Other 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	91,360	106,358
Securities purchased under resale agreements	5,203	3,012
Investment securities held-to-maturity	48,772	40,111
Net loans	31,009	29,862
Other	1	1
Financial Liabilities:
Non-interest-bearing	55,062	56,461
Interest-bearing - U.S.	107,262	102,985
Interest-bearing - non-U.S.	79,589	95,589
Securities sold under repurchase agreements	951	1,575
Other short-term borrowings	73	128
Long-term debt	12,633	13,385
Other	1	1
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	2,200	2,666
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
Other short-term borrowings	0	0
Long-term debt	138	167
Other	$ 0	$ 0