Credit Risk Concentrations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Credit exposure	$ 2,108,242	$ 2,004,974
On-balance sheet, Loans	984,554	930,697
On-balance sheet, Derivatives	54,213	56,523
Off-balance sheet	1,039,258	991,482
Available-for-sale securities	230,394	201,678
Held-to-maturity securities	31,434	47,733
Cash Placed with Banks	268,100	421,000
Obligations of U.S. states and municipalities
Concentration Risk [Line Items]
Trading securities	7,800	9,800
Available-for-sale securities	37,723	32,338
Held-to-maturity securities	4,824	14,373
Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	54,213	56,523
Consumer | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	1,181,963	1,143,709
On-balance sheet, Loans	530,364	522,192
Off-balance sheet	651,445	621,384
Consumer, excluding credit card
Concentration Risk [Line Items]
On-balance sheet, Loans	373,732	372,681
Consumer, excluding credit card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	419,798	421,234
On-balance sheet, Loans	373,732	372,681
Off-balance sheet	46,066	48,553
Consumer, excluding credit card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	419,952	421,367
On-balance sheet, Loans	373,732	372,681
Off-balance sheet	46,066	48,553
Credit card
Concentration Risk [Line Items]
On-balance sheet, Loans	156,632	149,511
Credit card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	762,011	722,342
On-balance sheet, Loans	156,632	149,511
Off-balance sheet	605,379	572,831
Wholesale
Concentration Risk [Line Items]
On-balance sheet, Loans	454,190	408,505
Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	926,279	861,265
On-balance sheet, Loans	454,190	408,505
Off-balance sheet	387,813	370,098
Receivables from customers and other | Consumer, excluding credit card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	154	133
Receivables from customers and other | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	30,063	26,139
Wholesale-related | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	54,213	56,523
Wholesale-related | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	881,188	829,519
On-balance sheet, Loans	439,162	402,898
Off-balance sheet	387,813	370,098
Real Estate | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	164	153
Real Estate | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	143,316	139,409
On-balance sheet, Loans	115,737	113,648
Off-balance sheet	27,415	25,608
Individuals and Individual Entities | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,017	1,252
Individuals and Individual Entities | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	97,077	87,371
On-balance sheet, Loans	86,586	77,768
Off-balance sheet	9,474	8,351
Consumer & Retail | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,093	1,114
Consumer & Retail | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	94,815	87,679
On-balance sheet, Loans	36,921	31,044
Off-balance sheet	56,801	55,521
Technology, Media & Telecommunications | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,667	2,265
Technology, Media & Telecommunications | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	72,646	59,274
On-balance sheet, Loans	16,980	13,665
Off-balance sheet	52,999	43,344
Industrials | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	958	1,163
Industrials | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	58,528	55,272
On-balance sheet, Loans	19,126	18,161
Off-balance sheet	38,444	35,948
Banks & Finance Cos | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	5,903	6,816
Banks & Finance Cos | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	49,920	49,037
On-balance sheet, Loans	28,825	25,879
Off-balance sheet	15,192	16,342
Healthcare | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,874	2,191
Healthcare | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	48,142	55,997
On-balance sheet, Loans	16,347	16,273
Off-balance sheet	29,921	37,533
Asset Managers | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	9,033	7,998
Asset Managers | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	42,807	32,531
On-balance sheet, Loans	16,806	11,480
Off-balance sheet	16,968	13,053
Oil & Gas | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	559	1,727
Oil & Gas | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	42,600	41,317
On-balance sheet, Loans	13,008	12,621
Off-balance sheet	29,033	26,969
Utilities | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,740	2,084
Utilities | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	28,172	29,317
On-balance sheet, Loans	5,591	6,187
Off-balance sheet	20,841	21,046
State & Municipal Govt | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,000	2,888
State & Municipal Govt | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	27,351	28,633
On-balance sheet, Loans	10,319	12,134
Off-balance sheet	15,032	13,611
Central Govt | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	12,869	13,937
Central Govt | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	18,456	19,182
On-balance sheet, Loans	3,867	3,375
Off-balance sheet	1,720	1,870
Automotive | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	399	342
Automotive | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	17,339	14,820
On-balance sheet, Loans	5,170	4,903
Off-balance sheet	11,770	9,575
Chemicals & Plastics | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	181	208
Chemicals & Plastics | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	16,035	15,945
On-balance sheet, Loans	4,902	5,654
Off-balance sheet	10,952	10,083
Transportation | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,102	977
Transportation | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	15,660	15,797
On-balance sheet, Loans	6,391	6,733
Off-balance sheet	8,167	8,087
Metals & Mining | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	488	702
Metals & Mining | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	15,359	14,171
On-balance sheet, Loans	5,370	4,728
Off-balance sheet	9,501	8,741
Insurance | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,569	2,804
Insurance | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	12,639	14,089
On-balance sheet, Loans	1,356	1,411
Off-balance sheet	8,714	9,874
Financial Markets Infrastructure | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	5,941	3,499
Financial Markets Infrastructure | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	7,484	5,036
On-balance sheet, Loans	18	351
Off-balance sheet	1,525	1,186
Securities Firms | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,029	1,692
Securities Firms | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	4,558	4,113
On-balance sheet, Loans	645	952
Off-balance sheet	1,884	1,469
All other | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,627	2,711
All other | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	68,284	60,529
On-balance sheet, Loans	45,197	35,931
Off-balance sheet	$ 21,460	$ 21,887
All other | Wholesale | Credit Concentration Risk | Credit Exposure, Secured by Highly Liquid Forms of Collateral
Concentration Risk [Line Items]
Percentage of exposure secured	92.00%	90.00%
All other | Wholesale | Credit Concentration Risk | Credit Exposure, Secured by Less Liquid Forms of Collateral
Concentration Risk [Line Items]
Percentage of exposure secured	8.00%	10.00%
Loans held-for-sale and loans at fair value | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	$ 15,028	$ 5,607
On-balance sheet, Loans	$ 15,028	$ 5,607