Derivatives and Hedging Activities - OTC Derivatives by Product Type and Tenor (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Assets	$ 45,252	$ 44,846
Derivative Liabilities	43,802	42,594
OTC [Member]
Derivative [Line Items]
Derivative Assets	114,650	102,443
Derivative Liabilities	95,630	91,814
OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	78,098	63,413
Derivative Liabilities	49,237	42,723
OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	7,120	7,847
Derivative Liabilities	7,180	6,712
OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	21,544	22,538
Derivative Liabilities	23,428	24,898
OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	4,021	7,224
Derivative Liabilities	8,550	10,079
OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	13,135	11,535
Derivative Liabilities	16,503	17,516
OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(9,268)	(10,114)
Derivative Liabilities	(9,268)	(10,114)
OTC [Member] | Cross Tenor Counterparty Netting [Member]
Derivative [Line Items]
Derivative Assets	(15,639)	(13,143)
Derivative Liabilities	(15,639)	(13,143)
OTC [Member] | Cash Collateral Netting [Member]
Derivative [Line Items]
Cash collateral netting	(56,000)	(48,724)
Cash collateral netting	(42,144)	(39,127)
OTC [Member] | Counterparty and Cash Collateral Netting [Member]
Derivative [Line Items]
Derivative Assets	43,011	40,576
Derivative Liabilities	37,847	39,544
Less than 1 Year [Member] | OTC [Member]
Derivative [Line Items]
Derivative Assets	23,011	21,124
Derivative Liabilities	22,796	29,013
Less than 1 Year [Member] | OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	5,521	2,810
Derivative Liabilities	3,654	4,193
Less than 1 Year [Member] | OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	678	807
Derivative Liabilities	1,368	1,127
Less than 1 Year [Member] | OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	10,236	10,976
Derivative Liabilities	12,486	13,553
Less than 1 Year [Member] | OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	2,507	4,978
Derivative Liabilities	2,796	4,271
Less than 1 Year [Member] | OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	7,332	4,962
Derivative Liabilities	5,755	9,278
Less than 1 Year [Member] | OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(3,263)	(3,409)
Derivative Liabilities	(3,263)	(3,409)
1 - 5 Years [Member] | OTC [Member]
Derivative [Line Items]
Derivative Assets	25,553	25,391
Derivative Liabilities	25,729	24,155
1 - 5 Years [Member] | OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	15,183	13,177
Derivative Liabilities	9,113	9,153
1 - 5 Years [Member] | OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	3,259	3,676
Derivative Liabilities	4,052	4,173
1 - 5 Years [Member] | OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	5,063	5,076
Derivative Liabilities	6,906	6,871
1 - 5 Years [Member] | OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	1,212	2,101
Derivative Liabilities	1,950	2,663
1 - 5 Years [Member] | OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	4,509	5,244
Derivative Liabilities	7,381	5,178
1 - 5 Years [Member] | OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(3,673)	(3,883)
Derivative Liabilities	(3,673)	(3,883)
Greater than 5 Years [Member] | OTC [Member]
Derivative [Line Items]
Derivative Assets	66,086	55,928
Derivative Liabilities	47,105	38,646
Greater than 5 Years [Member] | OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	57,394	47,426
Derivative Liabilities	36,470	29,377
Greater than 5 Years [Member] | OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	3,183	3,364
Derivative Liabilities	1,760	1,412
Greater than 5 Years [Member] | OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	6,245	6,486
Derivative Liabilities	4,036	4,474
Greater than 5 Years [Member] | OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	302	145
Derivative Liabilities	3,804	3,145
Greater than 5 Years [Member] | OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	1,294	1,329
Derivative Liabilities	3,367	3,060
Greater than 5 Years [Member] | OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(2,332)	(2,822)
Derivative Liabilities	$ (2,332)	$ (2,822)