Fair Values of Assets and Liabilities - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Millions		Mar. 31, 2022		Dec. 31, 2021
Financial Assets
Cash and due from banks		$ 44,303		$ 28,905
Investment securities held-to-maturity		43,654	[1]	41,858
Loans		313,270		306,304
Financial Liabilities
Long-term debt		32,931		32,125
Carrying Amount [Member]
Financial Assets
Cash and due from banks		44,303		28,905
Federal funds sold and securities purchased under resale agreements		513		359
Investment securities held-to-maturity		43,654		41,858
Loans held for sale	[2]	1,118		1,152
Loans		313,270		306,304
Other	[3]	1,941		1,521
Financial Liabilities
Time deposits		24,304		22,665
Short-term borrowings	[4]	19,398		9,750
Long-term debt		32,931		32,125
Other	[5]	3,797		3,862
Fair Value [Member]
Financial Assets
Cash and due from banks		44,303		28,905
Federal funds sold and securities purchased under resale agreements		513		359
Investment securities held-to-maturity		40,572		41,812
Loans held for sale	[2]	1,118		1,152
Loans		311,120		312,724
Other	[3]	1,941		1,521
Financial Liabilities
Time deposits		23,952		22,644
Short-term borrowings	[4]	19,140		9,646
Long-term debt		32,228		32,547
Other	[5]	3,797		3,862
Fair Value [Member] | Level 1 [Member]
Financial Assets
Cash and due from banks		44,303		28,905
Fair Value [Member] | Level 2 [Member]
Financial Assets
Federal funds sold and securities purchased under resale agreements		513		359
Investment securities held-to-maturity		40,572		41,812
Other	[3]	1,129		630
Financial Liabilities
Time deposits		23,952		22,644
Short-term borrowings	[4]	19,140		9,646
Long-term debt		32,228		32,547
Other	[5]	1,151		1,170
Fair Value [Member] | Level 3 [Member]
Financial Assets
Loans held for sale	[2]	1,118		1,152
Loans		311,120		312,724
Other	[3]	812		891
Financial Liabilities
Other	[5]	$ 2,646		$ 2,692

[1] The weighted-average maturity of total held-to-maturity investment securities was 7.4 years at December 31, 2021, with a corresponding weighted-average yield of 1.45 percent. The weighted-average maturity of total available-for-sale investment securities was 5.5 years at December 31, 2021, with a corresponding weighted-average yield of 1.73 percent.

[2] Excludes mortgages held for sale for which the fair value option under applicable accounting guidance was elected.

[3] Includes investments in Federal Reserve Bank and Federal Home Loan Bank stock and tax-advantaged investments.

[4] Excludes the Company’s obligation on securities sold short required to be accounted for at fair value per applicable accounting guidance.

[5] Includes operating lease liabilities and liabilities related to tax-advantaged investments.