Derivatives and Hedging Activities - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Gross Fair Value of Derivative Asset Contracts Not Enforceable	$ 9,150	$ 10,680
Gross Fair Value of Derivative Liability Contracts Not Enforceable	14,880	14,580
Net Gains / (Losses) on Derivative assets and liabilities	(336)	1,140
Net Realized Gains / (Losses) on Derivative assets and liabilities	118	(113)
Net Unrealized Gains / (Losses) on Derivative assets and liabilities	(454)	1,251
Maximum Payout/Notional Amount of Written Credit Derivative	522,569	554,172
Maximum Payout/Notional Amount of Purchased Credit Derivatives	581,760	603,000
Net purchased protection notional value of credit derivatives	59,190	48,830
Foreign Currency Denominated Debt Designated As Foreign Currency Hedge	3,050	1,990
Net gain reclassified to earnings from accumulated other comprehensive income			$ 41
Net Investment Hedging [Member]
Derivative [Line Items]
Net gain reclassified to earnings from accumulated other comprehensive income			205
Net Investment Hedging [Member] | Non-US [Member]
Derivative [Line Items]
Net gain reclassified to earnings from accumulated other comprehensive income			$ (164)
Market making [Member]
Derivative [Line Items]
Net Gains / (Losses) on Derivative assets and liabilities	(305)	1,110
Other Principal Transactions [Member]
Derivative [Line Items]
Net Gains / (Losses) on Derivative assets and liabilities	$ 31	$ 28