For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Fair Values of Assets and Liabilities - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Financial Assets
Cash and due from banks	$ 44,047	$ 22,405	$ 15,272	$ 21,453
Loans	299,578	292,082
Financial Liabilities
Long-term debt	42,443	40,167
Carrying Amount [Member]
Financial Assets
Cash and due from banks	44,047	22,405
Federal funds sold and securities purchased under resale agreements	290	1,036
Loans held for sale	304	45
Loans	299,578	292,082
Other	1,818	1,923
Financial Liabilities
Time deposits	32,587	42,894
Short-term borrowings	11,971	22,095
Long-term debt	42,443	40,167
Other	3,541	3,678
Fair Value [Member]
Financial Assets
Cash and due from banks	44,047	22,405
Federal funds sold and securities purchased under resale agreements	290	1,036
Loans held for sale	304	43
Loans	310,721	297,241
Other	1,818	1,923
Financial Liabilities
Time deposits	32,675	42,831
Short-term borrowings	11,903	21,961
Long-term debt	43,657	41,077
Other	3,541	3,678
Fair Value [Member] \| Level 1 [Member]
Financial Assets
Cash and due from banks	44,047	22,405
Fair Value [Member] \| Level 2 [Member]
Financial Assets
Federal funds sold and securities purchased under resale agreements	290	1,036
Other	809	929
Financial Liabilities
Time deposits	32,675	42,831
Short-term borrowings	11,903	21,961
Long-term debt	43,657	41,077
Other	1,245	1,342
Fair Value [Member] \| Level 3 [Member]
Financial Assets
Loans held for sale	304	43
Loans	310,721	297,241
Other	1,009	994
Financial Liabilities
Other	$ 2,296	$ 2,336