Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	$ 1,165,688	$ 1,108,399
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	812,715
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	183,964
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	136,783
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	32,226
Off-balance sheet lending-related financial commitments, Carrying value	2,753	1,586
Warranty Reserves
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	84	59
Total consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	715,825	690,889
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	695,765
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,598
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	3,970
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	14,492
Off-balance sheet lending-related financial commitments, Carrying value	148	12
Total consumer, excluding credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	57,319	40,169
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	37,259
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,598
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	3,970
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	14,492
Off-balance sheet lending-related financial commitments, Carrying value	148	12
Residential real estate
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	46,047	30,217
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	26,788
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,597
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	3,962
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	13,700
Off-balance sheet lending-related financial commitments, Carrying value	148	12
Auto and other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	11,272	9,952
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	10,471
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	8
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	792
Off-balance sheet lending-related financial commitments, Carrying value	0	0
Credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	658,506	650,720
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	658,506
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	0
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	0
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	0
Off-balance sheet lending-related financial commitments, Carrying value	0	0
Total wholesale
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	449,863	417,510
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	116,950
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	182,366
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	132,813
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	17,734
Off-balance sheet lending-related financial commitments, Carrying value	2,605	1,574
Other unfunded commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	415,828	380,307
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	96,490
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	174,335
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	128,736
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	16,267
Off-balance sheet lending-related financial commitments, Carrying value	2,148	952
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other unfunded commitments to extend credit	72	76
Standby letters of credit and other financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	30,982	34,242
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	17,478
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	7,986
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,051
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	1,467
Off-balance sheet lending-related financial commitments, Carrying value	443	618
Other guarantees and commitments, Carrying value	363	402
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	80	216
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for standby letters of credit and other financial guarantees	8,500	9,800
Other letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	3,053	2,961
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	2,982
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	45
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	26
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	0
Off-balance sheet lending-related financial commitments, Carrying value	14	4
Other guarantees and commitments, Carrying value	0	0
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	14	4
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other letters of credit	357	546
Securities lending indemnification agreements and guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	250,418	204,827
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	250,418
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	0
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	0
Other guarantees and commitments, Contractual amount, Expiring after 5 years	0
Other guarantees and commitments, Carrying value	0	0
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Indemnification agreement securities lending guarantees collateral held in support of	264,300	216,200
Derivatives qualifying as guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	54,415	53,089
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	2,489
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	541
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	12,182
Other guarantees and commitments, Contractual amount, Expiring after 5 years	39,203
Other guarantees and commitments, Carrying value	322	159
Unsettled resale and securities borrowed agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	96,848	117,951
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	95,084
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	1,764
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	0
Other guarantees and commitments, Contractual amount, Expiring after 5 years	0
Other guarantees and commitments, Carrying value	2	0
Unsettled repurchase and securities loaned agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	104,901	73,351
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	104,289
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	612
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	0
Other guarantees and commitments, Contractual amount, Expiring after 5 years	0
Other guarantees and commitments, Carrying value	(1)	0
Loans sold with recourse
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan sale and securitization-related indemnifications, Loans sold with recourse, Contractual amount	889	944
Loan sale and securitization-related indemnifications, Loans sold with recourse, Carrying value	23	27
Exchange & clearing house guarantees and commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	142,003	206,432
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	142,003
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	0
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	0
Other guarantees and commitments, Contractual amount, Expiring after 5 years	0
Other guarantees and commitments, Carrying value	0	0
Other guarantees and commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	6,330	6,334
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	2,457
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	574
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	758
Other guarantees and commitments, Contractual amount, Expiring after 5 years	2,541
Other guarantees and commitments, Carrying value	$ 52	$ (66)
Days Past Due, 60 or More | Credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Line of credit close criteria, period past due	60 days