v3.21.2
Trading Cash Instruments - Cash Instruments by Level (Detail) - USD ($)
$ in Millions
Jun. 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 $ 309,565 $ 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 208,677 216,370
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 99,584 106,442
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 1,304 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 95,354 138,533
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 69,578 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 25,725 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 51  
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 68,274 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 52,410 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 15,859 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 5 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 1,241 800
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 1,145 597
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 96 203
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 7,655 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 7,525 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 130 131
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 37,811 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 572 915
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 36,348 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 891 797
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 238 200
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 238 200
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 2,517 1,412
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 258 338
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 2,206 1,055
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 19
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 88,479 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 85,859 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 2,542 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 78 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 7,996 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 7,996 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 (150,399) (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 (133,710) (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 (16,611) (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 (78) (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 (29,155) (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 (29,090) (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 (65) (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 (40,043) (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 (36,951) (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 (3,092) (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 (40) (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 (40) (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)
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 (3) (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 (3) (1)
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 (12,767) (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 (57) (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 (12,663) (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 (47) (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) (2)
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 (1) (2)
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 (68,364) (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 (67,612) (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 (722) (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 (30) $ (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 (26)  
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 $ (26)