Derivative Instruments and Hedging Activities - Effects of Fair Value and Cash Flow Hedge Accounting (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Interest and dividend income, securities	$ 499	$ 317	$ 1,336	$ 1,078
Interest and fee income, loans	7,578	6,205	20,550	17,812
Interest and dividend income, other	123	16	193	48
Deposits	(689)	(228)	(1,200)	(734)
Securitized debt obligations	(120)	(29)	(214)	(89)
Senior and subordinated notes	(319)	(116)	(644)	(367)
Non-interest income (loss)	192	245	634	598
Amortization expense (benefit)	(23)	34	(57)	(10)
Loss (net after-tax) recorded in AOCI related to derivatives designated as cash flow hedges expected to be reclassified to earnings over the next 12 months			$ 690
Maximum length of time over which forecasted transactions were hedged, years			5 years 6 months
Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Realized losses (gains) on foreign exchange contracts reclassified from AOCI	79	83	$ 98	245
Cash flow hedges | Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on cash flow hedges	0	10	0	30
Cash flow hedges | Interest income - Loans
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on cash flow hedges	(86)	240	104	700
Cash flow hedges | Interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on cash flow hedges	2	0	1	1
Cash flow hedges | Interest expense - Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) 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 (expense) 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 (expense) recognized on cash flow hedges	0	0	0	0
Cash flow hedges | Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on cash flow hedges	(1)	0	(1)	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	0	10	0	30
Cash flow hedges | Interest rate contracts | Interest income - Loans
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification adjustment from AOCI on derivatives, net of tax	(86)	240	104	700
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	0	1	1
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	(1)	0	(1)	1
Fair value hedges | Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	3	(89)	(48)	(151)
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	4	30	47	100
Fair value hedges | Interest expense - Securitized Debt Obligation
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	(20)	27	12	79
Fair value hedges | Interest expense - Senior and Subordinated Debt
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	(33)	80	94	262
Fair value hedges | Non interest income - Other
Derivative Instruments, Gain (Loss) [Line Items]
Net income (expense) recognized on fair value hedges	0	0	(1)	0
Fair value hedges | Interest rate contracts | Interest income - Investment securities
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	22	(25)	22	(75)
Gains (losses) recognized on derivatives	83	19	294	130
Gains (losses) recognized on hedged items	(102)	(83)	(364)	(206)
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0	0	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	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	0	0
Fair value hedges | Interest rate contracts | Interest expense - Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	4	31	46	101
Gains (losses) recognized on derivatives	(381)	(28)	(569)	(117)
Gains (losses) recognized on hedged items	381	27	570	116
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0	0	0	0
Fair value hedges | Interest rate contracts | Interest expense - Securitized Debt Obligation
Derivative Instruments, Gain (Loss) [Line Items]
Interest recognized on derivatives	(21)	30	12	93
Gains (losses) recognized on derivatives	(311)	(57)	(735)	(154)
Gains (losses) recognized on hedged items	312	54	735	140
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	0	0	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)	50	(20)	168
Gains (losses) recognized on derivatives	(807)	(72)	(2,039)	(408)
Gains (losses) recognized on hedged items	846	103	2,155	504
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	(1)	(1)	(2)	(2)
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	(85)	(34)	(197)	(79)
Gains (losses) recognized on hedged items	85	34	196	79
Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net	$ 0	$ 0	$ 0	$ 0