Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	$ 1,242,022	$ 1,165,688
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	857,814
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	195,753
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	152,348
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	36,107
Off-balance sheet lending-related financial commitments, Carrying value	3,570	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	739,406	715,825
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	720,262
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,900
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,789
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	12,455
Off-balance sheet lending-related financial commitments, Carrying value	103	148
Total consumer, excluding credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	56,875	57,319
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	37,731
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,900
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,789
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	12,455
Off-balance sheet lending-related financial commitments, Carrying value	103	148
Residential real estate
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	44,393	46,047
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	26,071
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,900
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,789
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	11,633
Off-balance sheet lending-related financial commitments, Carrying value	103	148
Auto and other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	12,482	11,272
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	11,660
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	822
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	682,531	658,506
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	682,531
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	502,616	449,863
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	137,552
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	193,853
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	147,559
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	23,652
Off-balance sheet lending-related financial commitments, Carrying value	3,467	2,605
Other unfunded commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	463,573	415,828
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	116,310
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	186,067
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	138,839
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	22,357
Off-balance sheet lending-related financial commitments, Carrying value	2,796	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	70	72
Standby letters of credit and other financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	34,876	30,982
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	17,489
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	7,622
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	8,471
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	1,294
Off-balance sheet lending-related financial commitments, Carrying value	663	443
Other guarantees and commitments, Carrying value	596	363
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	67	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	4,167	3,053
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	3,753
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	164
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	249
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	1
Off-balance sheet lending-related financial commitments, Carrying value	8	14
Other guarantees and commitments, Carrying value	0	0
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	8	14
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other letters of credit	808	357
Securities lending indemnification agreements and guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	303,869	250,418
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	303,869
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	320,600	264,300
Derivatives qualifying as guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	57,101	54,415
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	5,509
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	130
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	11,603
Other guarantees and commitments, Contractual amount, Expiring after 5 years	39,859
Other guarantees and commitments, Carrying value	308	322
Unsettled resale and securities borrowed agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	175,991	102,355
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	173,862
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	2,129
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	2
Unsettled repurchase and securities loaned agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	109,610	104,901
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	109,014
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	596
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	822	889
Loan sale and securitization-related indemnifications, Loans sold with recourse, Carrying value	21	23
Exchange & clearing house guarantees and commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	109,977	142,003
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	109,977
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	11,506	9,639
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	6,506
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	2,945
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	328
Other guarantees and commitments, Contractual amount, Expiring after 5 years	1,727
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