Off-balance Sheet Lending-related Financial Instruments, Guarantees, and Other Commitments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	$ 1,079,762	$ 1,039,258	$ 1,045,993
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	741,649
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	143,208
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	166,431
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	28,474
Off-balance sheet lending-related financial commitments, Carrying value	1,473	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	89	89
Total Consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	685,461	651,445
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	662,193
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	2,843
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	2,384
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	18,041
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	51,491	46,066
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	28,223
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	2,843
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	2,384
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	18,041
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	21,199	20,901
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	549
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	1,202
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	2,185
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	17,263
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	9,489	5,481
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	9,477
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	8,796	8,011
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	7,694
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	962
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	95
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	45
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	12,007	11,673
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	10,503
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	679
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	104
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	721
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	633,970	605,379
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	633,970
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	394,301	387,813
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	79,456
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	140,365
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	164,047
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	10,433
Off-balance sheet lending-related financial commitments, Carrying value	1,440	1,376
Other unfunded commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	358,782	351,490
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	61,732
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	129,593
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	159,234
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	8,223
Off-balance sheet lending-related financial commitments, Carrying value	883	852
Off balance sheet lending related financial instruments guarantees and other commitments - supplemental information [Abstract]
Risk participations for other unfunded commitments to extend credit	193	282
Standby letters of credit and other financial guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	32,196	33,498
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	14,658
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	10,552
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	4,776
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 5 years	2,210
Off-balance sheet lending-related financial commitments, Carrying value	554	521
Other guarantees and commitments, Carrying value	344	354
Loan sale and securitization-related indemnifications, Mortgage repurchase liability, Carrying value	210	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	9,500	10,400
Other letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total lending-related commitments	3,323	2,825
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring in 1 year or less	3,066
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 1 year through 3 years	220
Off-balance sheet lending-related financial commitments, Contractual amount, Expiring after 3 years through 5 years	37
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	682	385
Securities lending indemnification agreements and guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	203,868	186,077
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	203,868
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	214,600	195,600
Derivatives qualifying as guarantees
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	54,632	55,271
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	1,594
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	135
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	12,394
Other guarantees and commitments, Contractual amount, Expiring after 5 years	40,509
Other guarantees and commitments, Carrying value	228	367
Unsettled resale and securities borrowed agreements
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other guarantees and commitments, Contractual amount	114,164	102,008
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	113,218
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	875
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	71
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	122,806	57,732
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	122,806
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	1,031	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	164,784	58,960
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	164,784
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	11,722	8,183
Other guarantees and commitments, Contractual amount, Expiring in 1 year or less	4,505
Other guarantees and commitments, Contractual amount, Expiring after 1 year through 3 years	2,931
Other guarantees and commitments, Contractual amount, Expiring after 3 years through 5 years	1,537
Other guarantees and commitments, Contractual amount, Expiring after 5 years	2,749
Other guarantees and commitments, Carrying Value	$ (79)	$ (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