Derivatives and Hedging Activities - OTC Derivatives by Product Type and Tenor (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative Assets	$ 74,571	$ 45,252
Derivative Liabilities	62,039	43,802
OTC [Member]
Derivative [Line Items]
Derivative Assets	167,680	114,650
Derivative Liabilities	135,280	95,630
OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	101,964	78,098
Derivative Liabilities	66,924	49,237
OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	10,424	7,120
Derivative Liabilities	8,649	7,180
OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	37,046	21,544
Derivative Liabilities	36,505	23,428
OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	9,739	4,021
Derivative Liabilities	14,800	8,550
OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	21,969	13,135
Derivative Liabilities	21,864	16,503
OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(13,462)	(9,268)
Derivative Liabilities	(13,462)	(9,268)
OTC [Member] | Cross Tenor Counterparty Netting [Member]
Derivative [Line Items]
Derivative Assets	(20,977)	(15,639)
Derivative Liabilities	(20,977)	(15,639)
OTC [Member] | Cash Collateral Netting [Member]
Derivative [Line Items]
Cash collateral netting	(77,799)	(56,000)
Cash collateral netting	(59,983)	(42,144)
OTC [Member] | Counterparty and Cash Collateral Netting [Member]
Derivative [Line Items]
Derivative Assets	68,904	43,011
Derivative Liabilities	54,320	37,847
Less than 1 Year [Member] | OTC [Member]
Derivative [Line Items]
Derivative Assets	46,989	23,011
Derivative Liabilities	40,298	22,796
Less than 1 Year [Member] | OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	9,971	5,521
Derivative Liabilities	8,157	3,654
Less than 1 Year [Member] | OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	1,776	678
Derivative Liabilities	1,817	1,368
Less than 1 Year [Member] | OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	21,673	10,236
Derivative Liabilities	17,701	12,486
Less than 1 Year [Member] | OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	6,741	2,507
Derivative Liabilities	7,790	2,796
Less than 1 Year [Member] | OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	11,562	7,332
Derivative Liabilities	9,567	5,755
Less than 1 Year [Member] | OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(4,734)	(3,263)
Derivative Liabilities	(4,734)	(3,263)
1 - 5 Years [Member] | OTC [Member]
Derivative [Line Items]
Derivative Assets	36,870	25,553
Derivative Liabilities	34,149	25,729
1 - 5 Years [Member] | OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	21,382	15,183
Derivative Liabilities	12,908	9,113
1 - 5 Years [Member] | OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	4,342	3,259
Derivative Liabilities	4,433	4,052
1 - 5 Years [Member] | OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	6,428	5,063
Derivative Liabilities	11,104	6,906
1 - 5 Years [Member] | OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	2,486	1,212
Derivative Liabilities	2,711	1,950
1 - 5 Years [Member] | OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	7,238	4,509
Derivative Liabilities	7,999	7,381
1 - 5 Years [Member] | OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(5,006)	(3,673)
Derivative Liabilities	(5,006)	(3,673)
Greater than 5 Years [Member] | OTC [Member]
Derivative [Line Items]
Derivative Assets	83,821	66,086
Derivative Liabilities	60,833	47,105
Greater than 5 Years [Member] | OTC [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Assets	70,611	57,394
Derivative Liabilities	45,859	36,470
Greater than 5 Years [Member] | OTC [Member] | Credit Risk Contract [Member]
Derivative [Line Items]
Derivative Assets	4,306	3,183
Derivative Liabilities	2,399	1,760
Greater than 5 Years [Member] | OTC [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Assets	8,945	6,245
Derivative Liabilities	7,700	4,036
Greater than 5 Years [Member] | OTC [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative Assets	512	302
Derivative Liabilities	4,299	3,804
Greater than 5 Years [Member] | OTC [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Assets	3,169	1,294
Derivative Liabilities	4,298	3,367
Greater than 5 Years [Member] | OTC [Member] | Counterparty Netting in Tenors [Member]
Derivative [Line Items]
Derivative Assets	(3,722)	(2,332)
Derivative Liabilities	$ (3,722)	$ (2,332)