v3.21.2
Trading Cash Instruments - Cash Instruments by Level (Detail) - USD ($)
$ in Millions
Sep. 30, 2021
Dec. 31, 2020
Trading Cash Instruments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Trading Assets $ 321,415 $ 324,049
Trading cash instruments assets | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 217,679 216,370
Trading cash instruments assets | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 102,220 106,442
Trading cash instruments assets | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 1,516 1,237
Trading cash instruments assets | U.S. Government and Agency Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 100,479 138,533
Trading cash instruments assets | U.S. Government and Agency Obligations [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 76,579 93,670
Trading cash instruments assets | U.S. Government and Agency Obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 23,883 44,863
Trading cash instruments assets | U.S. Government and Agency Obligations [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 17  
Trading cash instruments assets | Non-U.S. Government and Agency Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 56,126 57,423
Trading cash instruments assets | Non-U.S. Government and Agency Obligations [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 40,510 46,147
Trading cash instruments assets | Non-U.S. Government and Agency Obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 15,600 11,261
Trading cash instruments assets | Non-U.S. Government and Agency Obligations [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 16 15
Trading cash instruments assets | Loans and Securities Backed by Commercial Real Estate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 1,185 800
Trading cash instruments assets | Loans and Securities Backed by Commercial Real Estate [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 1,049 597
Trading cash instruments assets | Loans and Securities Backed by Commercial Real Estate [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 136 203
Trading cash instruments assets | Loans and Securities Backed by Residential Real Estate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 10,282 7,079
Trading cash instruments assets | Loans and Securities Backed by Residential Real Estate [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 10,160 6,948
Trading cash instruments assets | Loans and Securities Backed by Residential Real Estate [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 122 131
Trading cash instruments assets | Corporate debt instruments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 40,177 31,351
Trading cash instruments assets | Corporate debt instruments [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 588 915
Trading cash instruments assets | Corporate debt instruments [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 38,493 29,639
Trading cash instruments assets | Corporate debt instruments [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 1,096 797
Trading cash instruments assets | State and Municipal Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 753 200
Trading cash instruments assets | State and Municipal Obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 752 200
Trading cash instruments assets | State and Municipal Obligations [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 1  
Trading cash instruments assets | Other debt obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 2,270 (2)
Trading cash instruments assets | Other debt obligations [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 72  
Trading cash instruments assets | Other debt obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 2,145  
Trading cash instruments assets | Other debt obligations [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 53 (2)
Trading cash instruments assets | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 102,760 77,877
Trading cash instruments assets | Equity Securities [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 99,930 75,300
Trading cash instruments assets | Equity Securities [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 2,755 2,505
Trading cash instruments assets | Equity Securities [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 75 72
Trading cash instruments assets | Commodities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 7,383 9,374
Trading cash instruments assets | Commodities [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Assets at Fair Value 7,383 9,374
Cash Instruments Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (150,763) (95,136)
Cash Instruments Liabilities [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (130,640) (84,708)
Cash Instruments Liabilities [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (19,985) (10,348)
Cash Instruments Liabilities [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (138) (80)
Cash Instruments Liabilities [Member] | U.S. Government and Agency Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (28,584) (16,893)
Cash Instruments Liabilities [Member] | U.S. Government and Agency Obligations [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (28,554) (16,880)
Cash Instruments Liabilities [Member] | U.S. Government and Agency Obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (30) (13)
Cash Instruments Liabilities [Member] | Non-U.S. Government and Agency Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (42,076) (23,884)
Cash Instruments Liabilities [Member] | Non-U.S. Government and Agency Obligations [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (39,190) (22,092)
Cash Instruments Liabilities [Member] | Non-U.S. Government and Agency Obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (2,886) (1,792)
Cash Instruments Liabilities [Member] | Loans and Securities Backed by Commercial Real Estate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (43) (18)
Cash Instruments Liabilities [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (42) (17)
Cash Instruments Liabilities [Member] | Loans and Securities Backed by Commercial Real Estate [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (1) (1)
Cash Instruments Liabilities [Member] | Loans and Securities Backed by Residential Real Estate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (11) (1)
Cash Instruments Liabilities [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value   (1)
Cash Instruments Liabilities [Member] | Loans and Securities Backed by Residential Real Estate [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (11)  
Cash Instruments Liabilities [Member] | Corporate debt instruments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (16,551) (8,022)
Cash Instruments Liabilities [Member] | Corporate debt instruments [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (72) (2)
Cash Instruments Liabilities [Member] | Corporate debt instruments [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (16,380) (7,970)
Cash Instruments Liabilities [Member] | Corporate debt instruments [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (99) (50)
Cash Instruments Liabilities [Member] | State and Municipal Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value   (5)
Cash Instruments Liabilities [Member] | State and Municipal Obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value   (5)
Cash Instruments Liabilities [Member] | Other debt obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value   1,412
Cash Instruments Liabilities [Member] | Other debt obligations [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value   338
Cash Instruments Liabilities [Member] | Other debt obligations [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value   1,055
Cash Instruments Liabilities [Member] | Other debt obligations [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value   19
Cash Instruments Liabilities [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (63,490) (46,311)
Cash Instruments Liabilities [Member] | Equity Securities [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (62,824) (45,734)
Cash Instruments Liabilities [Member] | Equity Securities [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (639) (550)
Cash Instruments Liabilities [Member] | Equity Securities [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (27) $ (27)
Cash Instruments Liabilities [Member] | Commodities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value (8)  
Cash Instruments Liabilities [Member] | Commodities [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Trading Cash Instruments Liabilities at Fair Value $ (8)