Derivative Instruments - Customer-Related Derivative Positions of Company (Detail) - Customer-Related Positions [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Notional Value, Assets	$ 298,775	$ 294,310
Fair Value, Assets	4,099	5,552
Notional Value, Liabilities	292,257	282,040
Fair Value, Liabilities	2,837	3,054
Interest Rate Contracts [Member] \| Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	121,392	144,859
Fair Value, Assets	$ 2,416	$ 3,782
Derivative Asset Average Remaining Maturity Period	4 years 5 months 1 day	4 years 11 months 4 days
Notional Value, Liabilities	$ 40,305	$ 12,027
Fair Value, Liabilities	$ 494	$ 99
Derivative Liability Average Remaining Maturity Period	7 years 6 months	8 years 8 months 19 days
Interest Rate Contracts [Member] \| Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	$ 39,173	$ 15,048
Fair Value, Assets	$ 115	$ 2
Derivative Asset Average Remaining Maturity Period	7 years 2 months 19 days	8 years 5 months 4 days
Notional Value, Liabilities	$ 115,251	$ 134,963
Fair Value, Liabilities	$ 801	$ 1,239
Derivative Liability Average Remaining Maturity Period	4 years 3 months 25 days	4 years 8 months 15 days
Interest Rate Contracts [Member] \| Other Derivatives [Member]
Derivative [Line Items]
Notional Value, Assets	$ 9,128	$ 9,921
Fair Value, Assets	$ 2	$ 6
Derivative Asset Average Remaining Maturity Period	3 years 8 months 26 days	3 years 9 months
Notional Value, Liabilities	$ 6,901	$ 6,387
Fair Value, Liabilities	$ 2	$ 3
Derivative Liability Average Remaining Maturity Period	4 years 8 months 23 days	4 years 2 months 19 days
Interest Rate Contracts [Member] \| Options [Member] \| Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 80,134	$ 72,655
Fair Value, Assets	$ 204	$ 111
Derivative Asset Average Remaining Maturity Period	1 year 3 months 25 days	1 year 4 months 24 days
Notional Value, Liabilities	$ 1,465	$ 1,454
Fair Value, Liabilities	$ 31	$ 46
Derivative Liability Average Remaining Maturity Period	2 years 8 months 15 days	2 years 11 months 15 days
Interest Rate Contracts [Member] \| Options [Member] \| Written [Member]
Derivative [Line Items]
Notional Value, Assets	$ 1,391	$ 1,736
Fair Value, Assets	$ 31	$ 46
Derivative Asset Average Remaining Maturity Period	2 years 9 months 7 days	2 years 9 months 3 days
Notional Value, Liabilities	$ 75,365	$ 68,205
Fair Value, Liabilities	$ 195	$ 81
Derivative Liability Average Remaining Maturity Period	1 year 3 months	1 year 3 months
Interest Rate Contracts [Member] \| Futures [Member] \| Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 921	$ 1,851
Derivative Asset Average Remaining Maturity Period	11 months 12 days	1 year 2 months 19 days
Notional Value, Liabilities	$ 1,628	$ 924
Derivative Liability Average Remaining Maturity Period	1 year 1 month 20 days	18 days
Interest Rate Contracts [Member] \| Futures [Member] \| Written [Member]
Derivative [Line Items]
Notional Value, Assets	$ 1,468
Derivative Asset Average Remaining Maturity Period	1 year 1 month 6 days
Notional Value, Liabilities	$ 1,310	$ 4,090
Derivative Liability Average Remaining Maturity Period	5 months 12 days	8 months 19 days
Foreign Exchange Rate Contracts [Member] \| Forwards, Spots and Swaps [Member]
Derivative [Line Items]
Notional Value, Assets	$ 41,612	$ 44,845
Fair Value, Assets	$ 1,307	$ 1,590
Derivative Asset Average Remaining Maturity Period	1 year 1 month 2 days	11 months 15 days
Notional Value, Liabilities	$ 41,887	$ 45,992
Fair Value, Liabilities	$ 1,284	$ 1,565
Derivative Liability Average Remaining Maturity Period	1 year 3 months	1 year 1 month 17 days
Foreign Exchange Option [Member] \| Purchased [Member]
Derivative [Line Items]
Notional Value, Assets	$ 650	$ 519
Fair Value, Assets	$ 23	$ 14
Derivative Asset Average Remaining Maturity Period	11 months 23 days	10 months 24 days
Foreign Exchange Option [Member] \| Written [Member]
Derivative [Line Items]
Notional Value, Liabilities	$ 650	$ 519
Fair Value, Liabilities	$ 20	$ 14
Derivative Liability Average Remaining Maturity Period	11 months 23 days	10 months 24 days
Credit Contracts [Member]
Derivative [Line Items]
Notional Value, Assets	$ 2,906	$ 2,876
Fair Value, Assets	$ 1	$ 1
Derivative Asset Average Remaining Maturity Period	2 years 8 months 4 days	2 years 9 months
Notional Value, Liabilities	$ 7,495	$ 7,479
Fair Value, Liabilities	$ 10	$ 7
Derivative Liability Average Remaining Maturity Period	4 years 5 months 12 days	3 years 9 months 21 days

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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Nominal or face amount used to calculate payments on the derivative asset.

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-Publisher FASB
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