Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	$ 1,211,856	$ 1,165,688
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	843,170
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	189,225
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	143,609
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	35,852
Off-balance sheet lending-related financial commitments, Carrying value	3,214	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	72	84
Total Consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	730,612	715,825
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	710,897
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,741
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,349
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	13,625
Off-balance sheet lending-related financial commitments, Carrying value	203	148
Total consumer, excluding credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	56,245	57,319
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	36,530
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,741
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,349
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	13,625
Off-balance sheet lending-related financial commitments, Carrying value	203	148
Residential real estate
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	44,652	46,047
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	25,751
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,741
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,347
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	12,813
Off-balance sheet lending-related financial commitments, Carrying value	203	148
Auto and other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	11,593	11,272
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	10,779
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	2
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	812
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	674,367	658,506
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	674,367
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	481,244	449,863
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	132,273
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	187,484
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	139,260
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	22,227
Off-balance sheet lending-related financial commitments, Carrying value	3,011	2,605
Other unfunded commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	442,862	415,828
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	111,754
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	179,670
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	130,536
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	20,902
Off-balance sheet lending-related financial commitments, Carrying value	2,290	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	61	72
Standby letters of credit and other financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	34,773	30,982
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	17,294
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	7,658
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	8,497
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	1,324
Off-balance sheet lending-related financial commitments, Carrying value	692	443
Other guarantees and commitments, Carrying value	610	363
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	82	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	8,100	8,500
Other letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	3,609	3,053
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	3,225
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	156
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	227
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	1
Off-balance sheet lending-related financial commitments, Carrying value	29	14
Other guarantees and commitments, Carrying value	0	0
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	29	14
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other letters of credit	597	357
Securities lending indemnification agreements and guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	297,754	250,418
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	297,754
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	314,300	264,300
Derivatives qualifying as guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	53,580	54,415
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	2,142
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	195
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	12,043
Other guarantees and commitments, Contractual amount, Expiring after 5 years	39,200
Other guarantees and commitments, Carrying value	318	322
Unsettled resale and securities borrowed agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	154,167	96,848
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	151,549
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	2,618
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	3	2
Unsettled repurchase and securities loaned agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	108,433	104,901
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	107,597
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	836
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)	(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	823	889
Loan sale and securitization-related indemnifications, Loans sold with recourse, Carrying value	23	23
Exchange & clearing house guarantees and commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	84,852	142,003
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	84,852
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	11,952	9,639
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	8,545
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	627
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	363
Other guarantees and commitments, Contractual amount, Expiring after 5 years	2,417
Other guarantees and commitments, Carrying Value	$ 59	$ 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