Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	$ 1,039,258	$ 991,482	$ 975,152
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	708,578
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	137,929
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	161,458
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	31,293
Off-balance sheet lending-related financial commitments, Carrying value	1,409	1,512
Warranty Reserves
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	89	111
Total consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	651,445	621,384
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	629,178
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	2,539
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	1,993
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	17,735
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	46,066	48,553
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	23,799
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	2,539
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	1,993
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	17,735
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	20,901	20,360
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	796
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,095
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	1,813
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	17,197
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	5,481	5,736
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	5,469
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	8,011	9,255
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	6,954
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	878
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	78
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	101
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	11,673	13,202
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	10,580
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	566
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	102
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	425
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	605,379	572,831
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	605,379
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	387,813	370,098
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	79,400
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	135,390
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	159,465
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	13,558
Off-balance sheet lending-related financial commitments, Carrying value	1,376	1,479
Other unfunded commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	351,490	331,160
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	62,384
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	123,751
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	154,177
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	11,178
Off-balance sheet lending-related financial commitments, Carrying value	852	840
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other unfunded commitments to extend credit	282	334
Standby letters of credit and other financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	33,498	35,226
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	14,408
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	11,462
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	5,248
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	2,380
Off-balance sheet lending-related financial commitments, Carrying value	521	636
Other guarantees and commitments, Carrying value	354	444
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	167	192
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	10,400	10,400
Other letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	2,825	3,712
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	2,608
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	177
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	3	3
Other guarantees and commitments, Carrying value	0	0
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	3	3
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other letters of credit	385	405
Securities lending indemnification agreements and guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	186,077	179,490
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	186,077
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	195,600	188,700
Derivatives qualifying as guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	55,271	57,174
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	2,099
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	299
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	12,614
Other guarantees and commitments, Contractual amount, Expiring after 5 years	40,259
Other guarantees and commitments, Carrying value	367	304
Unsettled resale and securities borrowed agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	102,008	76,859
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	102,008
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
Unsettled repurchase and securities loaned agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	57,732	44,205
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	57,732
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	1,019	1,169
Loan sale and securitization-related indemnifications, Loans sold with recourse, Carrying value	30	38
Exchange & clearing house guarantees and commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	58,960	13,871
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	58,960
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	8,183	8,206
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	3,874
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	542
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	299
Other guarantees and commitments, Contractual amount, Expiring after 5 years	3,468
Other guarantees and commitments, Carrying value	$ (73)	$ (76)
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