Derivative Instruments and Hedging Activities - Effects of Fair Value and Cash Flow Hedge Accounting (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Interest and dividend income, securities	$ 482	$ 629	$ 1,012	$ 1,284
Interest and fee income, loans	5,820	6,383	12,362	12,751
Interest and dividend income, other	16	64	53	133
Deposits	(611)	(870)	(1,342)	(1,687)
Securitized debt obligations	(56)	(139)	(155)	(282)
Senior and subordinated notes	(180)	(310)	(419)	(624)
Non-interest income	166	191	311	348
Amortization of basis adjustment	17	56	53	117
Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Realized losses (gains) on foreign exchange contracts reclassified from AOCI	299	123	(93)	295
Fair value hedges \| Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	(21)	(2)	(32)	(1)
Fair value hedges \| Interest income - Loans
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	0	0	0	0
Fair value hedges \| Interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	0	0	0	0
Fair value hedges \| Interest expense - Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	26	(30)	25	(63)
Fair value hedges \| Interest expense - Securitized Debt Obligation
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	27	(29)	29	(59)
Fair value hedges \| Interest expense - Senior and Subordinated Debt
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	64	(50)	79	(100)
Fair value hedges \| Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	0	1	0	1
Fair value hedges \| Interest rate contracts \| Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	(17)	(1)	(28)	1
Gains (losses) recognized on derivatives	(26)	(175)	(364)	(286)
Gains (losses) recognized on hedged items	22	174	360	284
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0		0
Fair value hedges \| Interest rate contracts \| Interest income - Loans
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	0	0	0	0
Gains (losses) recognized on derivatives	0	0	0	0
Gains (losses) recognized on hedged items	0	0	0	0
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0		0
Fair value hedges \| Interest rate contracts \| Interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	0	0	0	0
Gains (losses) recognized on derivatives	0	0	0	0
Gains (losses) recognized on hedged items	0	0	0	0
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0		0
Fair value hedges \| Interest rate contracts \| Interest expense - Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	27	(33)	25	(69)
Gains (losses) recognized on derivatives	9	154	296	249
Gains (losses) recognized on hedged items	(10)	(151)	(296)	(243)
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0		0
Fair value hedges \| Interest rate contracts \| Interest expense - Securitized Debt Obligation
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	40	(6)	52	(12)
Gains (losses) recognized on derivatives	(13)	79	269	112
Gains (losses) recognized on hedged items	0	(102)	(292)	(159)
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0		0
Fair value hedges \| Interest rate contracts \| Interest expense - Senior and Subordinated Debt
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	71	(10)	110	(21)
Gains (losses) recognized on derivatives	61	471	1,129	752
Gains (losses) recognized on hedged items	(68)	(511)	(1,159)	(831)
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0		(1)
Fair value hedges \| Interest rate contracts \| Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	0	0	0	0
Gains (losses) recognized on derivatives	26	11	3	11
Gains (losses) recognized on hedged items	(26)	(10)	(3)	(10)
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0		0
Cash flow hedges \| Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Net income recognized on cash flow hedges	7	(3)	9	(7)
Cash flow hedges \| Interest income - Loans
Derivative Instruments, Gain (Loss) [Line Items]
Net income recognized on cash flow hedges	135	(59)	159	(115)
Cash flow hedges \| Interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Net income recognized on cash flow hedges	2	13	9	25
Cash flow hedges \| Interest expense - Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Net income recognized on cash flow hedges	0	0	0	0
Cash flow hedges \| Interest expense - Securitized Debt Obligation
Derivative Instruments, Gain (Loss) [Line Items]
Net income recognized on cash flow hedges	0	0	0	0
Cash flow hedges \| Interest expense - Senior and Subordinated Debt
Derivative Instruments, Gain (Loss) [Line Items]
Net income recognized on cash flow hedges	0	0	0	0
Cash flow hedges \| Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Net income recognized on cash flow hedges	(2)	(1)	(2)	(1)
Cash flow hedges \| Interest rate contracts \| Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	7	(3)	9	(7)
Cash flow hedges \| Interest rate contracts \| Interest income - Loans
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	135	(59)	159	(115)
Cash flow hedges \| Interest rate contracts \| Interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Interest rate contracts \| Interest expense - Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Interest rate contracts \| Interest expense - Securitized Debt Obligation
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Interest rate contracts \| Interest expense - Senior and Subordinated Debt
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Interest rate contracts \| Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Foreign exchange contracts \| Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Foreign exchange contracts \| Interest income - Loans
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Foreign exchange contracts \| Interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	2	13	9	25
Cash flow hedges \| Foreign exchange contracts \| Interest expense - Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Foreign exchange contracts \| Interest expense - Securitized Debt Obligation
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Foreign exchange contracts \| Interest expense - Senior and Subordinated Debt
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	0	0	0	0
Cash flow hedges \| Foreign exchange contracts \| Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	$ (2)	$ (1)	$ (2)	$ (1)

Amortization of basis adjustment

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Total amount of gain (loss) derived from cash flow hedges recognized in earnings in the period

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Gain or loss on fair value hedges recognized in net interest income

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Interest Expense, Secured Debt

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Realized Gains (Losses) on Foreign Exchange Contracts Reclassified from AOCI

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Net gain (loss) relating to components of the gain (loss) on the fair value hedging instrument excluded from the assessment of fair value hedge effectiveness. Recognized in earnings.

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Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

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