Derivatives and Hedging Activities - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Derivative [Line Items]
Gross Fair Value of Derivative Asset Contracts Not Enforceable	$ 17,910		$ 17,910		$ 17,090
Gross Fair Value of Derivative Liability Contracts Not Enforceable	16,780		16,780		18,160
Net Gains / (Losses) on Derivative assets and liabilities	(154)	$ 869	510	$ 1,130
Net Realized Gains / (Losses) on Derivative assets and liabilities	17	(22)	(110)	158
Net Unrealized Gains / (Losses) on Derivative assets and liabilities	(171)	891	620	967
Maximum Payout/Notional Amount of Written Credit Derivative	798,194		798,194		923,477
Maximum Payout/Notional Amount of Purchased Credit Derivatives	840,180		840,180		968,680
Net purchased protection notional value of credit derivatives	41,990		41,990		45,200
Net Gains (Losses), Including Hedges, Attributable to the Impact of Changes in Credit Exposure and Credit Spreads on Derivative Contracts	44	89	155	68
Foreign Currency Denominated Debt Designated As Foreign Currency Hedge	2,610		2,610		$ 2,200
Market making [Member]
Derivative [Line Items]
Net Gains / (Losses) on Derivative assets and liabilities	(16)	647	686	945
Other Principal Transactions [Member]
Derivative [Line Items]
Net Gains / (Losses) on Derivative assets and liabilities	$ (138)	$ 222	$ (176)	$ 180