Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	$ 1,095,090	$ 1,039,258	$ 1,048,674
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	751,251
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	142,778
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	169,929
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	31,132
Off-balance sheet lending-related financial commitments, Carrying value	1,555	1,409
Warranty Reserves
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	61	89
Total Consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	699,471	651,445
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	675,767
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	3,037
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	2,577
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	18,090
Off-balance sheet lending-related financial commitments, Carrying value	33	33
Total consumer, excluding credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	53,591	46,066
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	29,887
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	3,037
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	2,577
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	18,090
Off-balance sheet lending-related financial commitments, Carrying value	33	33
Home equity
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	21,183	20,901
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	597
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,156
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	2,353
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	17,077
Off-balance sheet lending-related financial commitments, Carrying value	12	12
Residential mortgage
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	10,916	5,481
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	10,904
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	12
Off-balance sheet lending-related financial commitments, Carrying value	0	0
Auto
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	9,467	8,011
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	8,062
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,238
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	118
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	49
Off-balance sheet lending-related financial commitments, Carrying value	2	2
Consumer & Business Banking
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	12,025	11,673
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	10,324
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	643
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	106
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	952
Off-balance sheet lending-related financial commitments, Carrying value	19	19
Credit card
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	645,880	605,379
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	645,880
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	395,619	387,813
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	75,484
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	139,741
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	167,352
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	13,042
Off-balance sheet lending-related financial commitments, Carrying value	1,522	1,376
Other unfunded commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	357,332	351,490
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	55,258
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	128,911
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	161,963
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	11,200
Off-balance sheet lending-related financial commitments, Carrying value	912	852
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other unfunded commitments to extend credit	198	282
Standby letters of credit and other financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	34,089	33,498
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	16,373
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	10,525
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	5,349
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	1,842
Off-balance sheet lending-related financial commitments, Carrying value	605	521
Other guarantees and commitments, Carrying value	390	354
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	215	167
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	9,700	10,400
Other letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	4,198	2,825
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	3,853
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	305
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	40
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	0
Off-balance sheet lending-related financial commitments, Carrying value	5	3
Other guarantees and commitments, Carrying value	0	0
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	5	3
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other letters of credit	705	385
Securities lending indemnification agreements and guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	214,338	186,077
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	214,338
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	226,500	195,600
Derivatives qualifying as guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	54,418	55,271
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	1,772
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	196
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	12,081
Other guarantees and commitments, Contractual amount, Expiring after 5 years	40,369
Other guarantees and commitments, Carrying value	231	367
Unsettled resale and securities borrowed agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	124,137	102,008
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	122,946
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	1,125
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	66
Other guarantees and commitments, Contractual amount, Expiring after 5 years	0
Other guarantees and commitments, Carrying value	0	0
Unsettled repurchase and securities loaned agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	121,349	57,732
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	120,679
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	670
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
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	1,001	1,019
Loan sale and securitization-related indemnifications, Loans sold with recourse, Carrying value	27	30
Exchange & clearing house guarantees and commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	161,580	58,960
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	161,580
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	7,780	8,183
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	4,098
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	590
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	260
Other guarantees and commitments, Contractual amount, Expiring after 5 years	2,832
Other guarantees and commitments, Carrying Value	$ (89)	$ (73)
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