Fair Value - Carrying Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financial Assets:
Cash and due from banks	$ 3,631	$ 3,467
Interest-bearing deposits with banks	106,358	116,960
Securities purchased under resale agreements	3,012	3,106
Investment securities held-to-maturity	42,271	50,003
Financial Liabilities:
Non-interest-bearing	56,461	49,439
Interest-bearing - U.S.	102,985	102,331
Interest-bearing - non-U.S.	95,589	88,028
Securities sold under repurchase agreements	1,575	3,413
Other short-term borrowings	128	685
Pricing Methods with Significant Observable Market Inputs (Level 2)
Financial Assets:
Net loans (excluding leases)	8
Reported Amount
Financial Assets:
Cash and due from banks	3,631	3,467
Interest-bearing deposits with banks	106,358	116,960
Securities purchased under resale agreements	3,012	3,106
Investment securities held-to-maturity	42,430	48,929
Net loans (excluding leases)	32,445	27,803
Other	1	4,753
Financial Liabilities:
Non-interest-bearing	56,461	49,439
Interest-bearing - U.S.	102,985	102,331
Interest-bearing - non-U.S.	95,589	88,028
Securities sold under repurchase agreements	1,575	3,413
Other short-term borrowings	128	685
Long-term debt	13,475	13,805
Other	1	4,753
Reported Amount  | HTM securities purchased under the MMLF program
Financial Assets:
Investment securities held-to-maturity		3,299
Reported Amount  | Short-term borrowings under the MMLF program
Financial Liabilities:
Other short-term borrowings		3,302
Estimated Fair Value
Financial Assets:
Cash and due from banks	3,631	3,467
Interest-bearing deposits with banks	106,358	116,960
Securities purchased under resale agreements	3,012	3,106
Investment securities held-to-maturity	42,271	50,003
Net loans (excluding leases)	32,528	27,884
Other	1	4,753
Financial Liabilities:
Non-interest-bearing	56,461	49,439
Interest-bearing - U.S.	102,985	102,331
Interest-bearing - non-U.S.	95,589	88,028
Securities sold under repurchase agreements	1,575	3,413
Other short-term borrowings	128	685
Long-term debt	13,552	14,162
Other	1	4,753
Estimated Fair Value | HTM securities purchased under the MMLF program
Financial Assets:
Investment securities held-to-maturity		3,304
Estimated Fair Value | Short-term borrowings under the MMLF program
Financial Liabilities:
Other short-term borrowings		3,302
Estimated Fair Value | Quoted Market Prices in Active Markets (Level 1)
Financial Assets:
Cash and due from banks	3,631	3,467
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held-to-maturity	2,160	6,115
Net loans (excluding leases)	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 | Quoted Market Prices in Active Markets (Level 1) | HTM securities purchased under the MMLF program
Financial Assets:
Investment securities held-to-maturity		0
Estimated Fair Value | Quoted Market Prices in Active Markets (Level 1) | Short-term borrowings under the MMLF program
Financial Liabilities:
Other short-term borrowings		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	106,358	116,960
Securities purchased under resale agreements	3,012	3,106
Investment securities held-to-maturity	40,111	43,888
Net loans (excluding leases)	29,862	25,668
Other	1	4,753
Financial Liabilities:
Non-interest-bearing	56,461	49,439
Interest-bearing - U.S.	102,985	102,331
Interest-bearing - non-U.S.	95,589	88,028
Securities sold under repurchase agreements	1,575	3,413
Other short-term borrowings	128	685
Long-term debt	13,385	14,049
Other	1	4,753
Estimated Fair Value | Pricing Methods with Significant Observable Market Inputs (Level 2)  | HTM securities purchased under the MMLF program
Financial Assets:
Investment securities held-to-maturity		3,304
Estimated Fair Value | Pricing Methods with Significant Observable Market Inputs (Level 2)  | Short-term borrowings under the MMLF program
Financial Liabilities:
Other short-term borrowings		3,302
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 (excluding leases)	2,666	2,216
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	167	113
Other	$ 0	0
Estimated Fair Value | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | HTM securities purchased under the MMLF program
Financial Assets:
Investment securities held-to-maturity		0
Estimated Fair Value | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Short-term borrowings under the MMLF program
Financial Liabilities:
Other short-term borrowings		$ 0