Derivative Instruments - Asset and Liability Management Derivative Positions of Company (Detail) - Asset and Liability Management Positions [Member] - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Notional Value, Assets		$ 65,519	$ 64,041
Fair Value, Assets		395	449
Notional Value, Liabilities		44,695	54,020
Fair Value, Liabilities		448	548
Other Derivatives [Member]
Derivative [Line Items]
Notional Value, Assets	[1]	951	47
Fair Value, Assets	[1]	$ 7	$ 1
Derivative Asset Average Remaining Maturity Period	[1]	10 days	1 month 9 days
Notional Value, Liabilities	[1]	$ 2,735	$ 1,832
Fair Value, Liabilities	[1]	$ 160	$ 183
Derivative Liability Average Remaining Maturity Period	[1]	1 year 3 months 25 days	2 years 5 months 8 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets		$ 8,070	$ 11,064
Derivative Asset Average Remaining Maturity Period		8 years 7 months 6 days	7 years 3 months 21 days
Notional Value, Liabilities		$ 2,614	$ 907
Derivative Liability Average Remaining Maturity Period		4 years 9 months 29 days	23 years 5 months 4 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets		$ 2,644	$ 78
Derivative Asset Average Remaining Maturity Period		3 years 1 month 2 days	13 years 8 months 4 days
Notional Value, Liabilities		$ 5,027	$ 8,538
Derivative Liability Average Remaining Maturity Period		5 years 3 months 7 days	5 years 8 months 1 day
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets		$ 8,096	$ 16,431
Fair Value, Assets		$ 33	$ 73
Derivative Asset Average Remaining Maturity Period		21 days	6 months
Notional Value, Liabilities		$ 5,231	$ 1,925
Fair Value, Liabilities		$ 18	$ 5
Derivative Liability Average Remaining Maturity Period		25 days	25 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Futures and Forwards [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets		$ 13,507	$ 10,440
Fair Value, Assets		$ 26	$ 48
Derivative Asset Average Remaining Maturity Period		4 months 2 days	14 days
Notional Value, Liabilities		$ 19,036	$ 28,976
Fair Value, Liabilities		$ 59	$ 157
Derivative Liability Average Remaining Maturity Period		29 days	25 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Options [Member] | Purchased [Member]
Derivative [Line Items]
Notional Value, Assets		$ 18,380	$ 11,610
Fair Value, Assets		$ 223	$ 121
Derivative Asset Average Remaining Maturity Period		3 years 3 months 3 days	4 years 1 month 9 days
Other Economic Hedges [Member] | Interest Rate Contracts [Member] | Options [Member] | Written [Member]
Derivative [Line Items]
Notional Value, Assets		$ 3,777	$ 5,073
Fair Value, Assets		$ 94	$ 202
Derivative Asset Average Remaining Maturity Period		1 month 2 days	1 month 17 days
Notional Value, Liabilities		$ 6,240	$ 7,770
Fair Value, Liabilities		$ 207	$ 198
Derivative Liability Average Remaining Maturity Period		2 years 3 months	2 years 6 months 10 days
Other Economic Hedges [Member] | Foreign Exchange Forward Contracts [Member]
Derivative [Line Items]
Notional Value, Assets		$ 394	$ 292
Fair Value, Assets		$ 5	$ 1
Derivative Asset Average Remaining Maturity Period		18 days	14 days
Notional Value, Liabilities		$ 185	$ 341
Fair Value, Liabilities		$ 4	$ 2
Derivative Liability Average Remaining Maturity Period		18 days	18 days
Other Economic Hedges [Member] | Equity Contracts [Member]
Derivative [Line Items]
Notional Value, Assets		$ 172	$ 127
Fair Value, Assets		$ 3	$ 3
Derivative Asset Average Remaining Maturity Period		10 months 28 days	4 months 20 days
Notional Value, Liabilities		$ 27	$ 45
Derivative Liability Average Remaining Maturity Period		10 months 24 days	5 months 15 days
Fair Value Hedges [Member] | Interest Rate Contracts [Member] | Receive Fixed/Pay Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Assets		$ 8,700	$ 8,400
Derivative Asset Average Remaining Maturity Period		3 years 3 days	1 year 9 months 3 days
Notional Value, Liabilities		$ 1,500
Derivative Liability Average Remaining Maturity Period		3 years 9 months 10 days
Fair Value Hedges [Member] | Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Liabilities		$ 1,850	$ 100
Derivative Liability Average Remaining Maturity Period		9 years 2 months 12 days	9 years 7 months 17 days
Cash Flow Hedges [Member] | Interest Rate Contracts [Member] | Pay Fixed/Receive Floating Swaps [Member]
Derivative [Line Items]
Notional Value, Liabilities		$ 250	$ 3,250
Derivative Liability Average Remaining Maturity Period		5 months 23 days	4 years 7 months 2 days
Net Investment Hedges [Member] | Foreign Exchange Forward Contracts [Member]
Derivative [Line Items]
Notional Value, Assets		$ 828	$ 479
Fair Value, Assets		$ 4
Derivative Asset Average Remaining Maturity Period		21 days	21 days
Notional Value, Liabilities			$ 336
Fair Value, Liabilities			$ 3
Derivative Liability Average Remaining Maturity Period			21 days

[1] (a) Includes derivative liability swap agreements related to the sale of a portion of the Company’s Class B common and preferred shares of Visa Inc. The Visa swap agreements had a total notional value, fair value and weighted-average remaining maturity of $1.8 billion, $154 million and 2.01 years at June 30, 2021, respectively, compared to $1.8 billion, $182 million and 2.50 years at December 31, 2020, respectively. In addition, includes short-term underwriting purchase and sale commitments with total asset and liability notional values of $951 million at June 30, 2021, and $47 million at December 31, 2020.