v3.20.4
Derivatives and Hedging Activities - Additional Information (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Derivative [Line Items]    
Gross Fair Value of Derivative Asset Contracts Not Enforceable $ 20,600 $ 9,150
Gross Fair Value of Derivative Liability Contracts Not Enforceable 22,980 14,880
Net Gains / (Losses) on Derivative assets and liabilities 838 (336)
Net Realized Gains / (Losses) on Derivative assets and liabilities 226 118
Net Unrealized Gains / (Losses) on Derivative assets and liabilities 612 (454)
Maximum Payout/Notional Amount of Written Credit Derivative 515,850 522,569
Maximum Payout/Notional Amount of Purchased Credit Derivatives 558,180 581,760
Net purchased protection notional value of credit derivatives 42,330 59,190
Foreign Currency Denominated Debt Designated As Foreign Currency Hedge 4,970 3,050
Expected Reduction in Gross Credit Derivative Assets Due to Each Day Settlement   3,970
Expected Reduction in Gross Credit Derivative Liabilities Due to Each Day Settlement   4,150
Net gain reclassified to earnings from accumulated other comprehensive income 61  
Foreign Exchange Forward [Member] | Derivative Contracts Accounted for as Hedges [Member]    
Derivative [Line Items]    
Hedging Assets, Current 2,090  
Available-for-sale securities loss (112)  
Available-for-sale securities gain 110  
Net Investment Hedging [Member]    
Derivative [Line Items]    
Net gain reclassified to earnings from accumulated other comprehensive income 214  
Net Investment Hedging [Member] | Non-US [Member]    
Derivative [Line Items]    
Net gain reclassified to earnings from accumulated other comprehensive income (153)  
Market making [Member]    
Derivative [Line Items]    
Net Gains / (Losses) on Derivative assets and liabilities 900 (305)
Other Principal Transactions [Member]    
Derivative [Line Items]    
Net Gains / (Losses) on Derivative assets and liabilities $ (62) $ 31