Fair Value, Assets and Liabilities, Fair Value Estimates for Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Financial assets
Cash and due from banks	$ 27,634	$ 24,616
Interest-earning deposits with banks	137,821	209,614
Federal funds sold and securities purchased under resale agreements	55,840	66,223
Held-to-maturity debt securities	300,434	272,022
Loans held for sale	9,434	23,617
Financial liabilities
Deposits	1,398,151	1,482,479	$ 1,470,379
Short-term borrowings	48,382	34,409
Long-term debt	156,412	160,689
Carrying value [Member]
Financial assets
Cash and due from banks	27,634	24,616
Interest-earning deposits with banks	137,821	209,614
Federal funds sold and securities purchased under resale agreements	55,840	66,223
Held-to-maturity debt securities	300,434	272,022
Loans held for sale	3,309	7,722
Loans, net	918,780	868,278
Nonmarketable equity securities	4,301	3,584
Total financial assets	1,448,119	1,452,059
Financial liabilities
Deposits	39,194	30,012
Short-term borrowings	48,222	34,409
Long-term debt	155,634	160,660
Total financial liabilities	243,050	225,081
Fair Value Disclosures, Textual [Abstract]
Deposit liabilities with no defined or contractual maturity	1,400,000	1,500,000
Carrying value [Member] | Finance leases [Member]
Financial liabilities
Long-term debt	23	26
Carrying value [Member] | Commercial lease financing [Member]
Financial assets
Loans, net	14,400	14,500
Estimated fair value [Member]
Financial assets
Cash and due from banks	27,634	24,616
Interest-earning deposits with banks	137,821	209,614
Federal funds sold and securities purchased under resale agreements	55,840	66,223
Held-to-maturity debt securities	255,571	272,386
Loans held for sale	3,359	7,929
Loans, net	886,492	883,963
Nonmarketable equity securities	4,363	3,646
Total financial assets	1,371,080	1,468,377
Financial liabilities
Deposits	38,144	30,002
Short-term borrowings	48,237	34,409
Long-term debt	152,917	168,084
Total financial liabilities	239,298	232,495
Fair Value Disclosures, Textual [Abstract]
Loan commitments and standby, commercial and similar letters of credit	800	1,400
Estimated fair value [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and due from banks	27,634	24,616
Interest-earning deposits with banks	137,618	209,452
Federal funds sold and securities purchased under resale agreements	0	0
Held-to-maturity debt securities	14,358	16,825
Loans held for sale	0	0
Loans, net	0	0
Nonmarketable equity securities	0	0
Total financial assets	179,610	250,893
Financial liabilities
Deposits	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Total financial liabilities	0	0
Estimated fair value [Member] | Fair value, inputs, level 2 [Member]
Financial assets
Cash and due from banks	0	0
Interest-earning deposits with banks	203	162
Federal funds sold and securities purchased under resale agreements	55,840	66,223
Held-to-maturity debt securities	238,580	252,717
Loans held for sale	1,652	6,300
Loans, net	58,172	63,404
Nonmarketable equity securities	0	0
Total financial assets	354,447	388,806
Financial liabilities
Deposits	25,093	14,401
Short-term borrowings	48,237	34,409
Long-term debt	151,895	166,682
Total financial liabilities	225,225	215,492
Estimated fair value [Member] | Fair value, inputs, level 3 [Member]
Financial assets
Cash and due from banks	0	0
Interest-earning deposits with banks	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Held-to-maturity debt securities	2,633	2,844
Loans held for sale	1,707	1,629
Loans, net	828,320	820,559
Nonmarketable equity securities	4,363	3,646
Total financial assets	837,023	828,678
Financial liabilities
Deposits	13,051	15,601
Short-term borrowings	0	0
Long-term debt	1,022	1,402
Total financial liabilities	$ 14,073	$ 17,003