Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	$ 1,266,530	$ 1,165,688
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	880,298
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	195,157
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	152,855
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	38,220
Off-balance sheet lending-related financial commitments, Carrying value	2,841	2,753
Warranty Reserves
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	61	84
Total Consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	767,294	715,825
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	748,613
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	2,030
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	5,313
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	11,338
Off-balance sheet lending-related financial commitments, Carrying value	130	148
Total consumer, excluding credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	56,684	57,319
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	38,003
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	2,030
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	5,313
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	11,338
Off-balance sheet lending-related financial commitments, Carrying value	130	148
Residential real estate
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	44,542	46,047
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	26,748
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	2,030
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	5,313
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	10,451
Off-balance sheet lending-related financial commitments, Carrying value	130	148
Auto and other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	12,142	11,272
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	11,255
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	887
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	710,610	658,506
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	710,610
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	499,236	449,863
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	131,685
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	193,127
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	147,542
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	26,882
Off-balance sheet lending-related financial commitments, Carrying value	2,711	2,605
Other unfunded commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	466,892	415,828
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	114,200
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	184,046
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	143,335
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	25,311
Off-balance sheet lending-related financial commitments, Carrying value	2,087	2,148
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other unfunded commitments to extend credit	48	72
Standby letters of credit and other financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	27,943	30,982
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	13,549
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	8,709
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,114
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	1,571
Off-balance sheet lending-related financial commitments, Carrying value	614	443
Other guarantees and commitments, Carrying value	536	363
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	78	80
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	7,900	8,500
Other letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	4,401	3,053
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	3,936
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	372
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	93
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	0
Off-balance sheet lending-related financial commitments, Carrying value	10	14
Other guarantees and commitments, Carrying value	0	0
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	10	14
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other letters of credit	609	357
Securities lending indemnification agreements and guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	306,562	250,418
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	306,562
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	324,000	264,300
Derivatives qualifying as guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	54,811	54,415
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	2,828
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	420
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	11,693
Other guarantees and commitments, Contractual amount, Expiring after 5 years	39,870
Other guarantees and commitments, Carrying value	390	322
Unsettled resale and securities borrowed agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	157,334	102,355
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	150,495
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	6,839
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	2
Unsettled repurchase and securities loaned agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	136,602	104,901
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	136,019
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	583
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	(1)
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	807	889
Loan sale and securitization-related indemnifications, Loans sold with recourse, Carrying value	20	23
Exchange & clearing house guarantees and commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	119,331	142,003
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	119,331
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	11,743	9,639
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	6,787
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	2,886
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	323
Other guarantees and commitments, Contractual amount, Expiring after 5 years	1,747
Other guarantees and commitments, Carrying value	$ 51	$ 52
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