Credit Risk Concentrations (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Credit exposure	$ 2,004,974	$ 1,951,555
On-balance sheet, Loans	930,697	894,765
On-balance sheet, Derivatives	56,523	64,078
Off-balance sheet	991,482	975,152
Available-for-sale securities	201,678	237,965
Held-to-maturity securities	47,733	50,168
Cash Placed with Banks	421,000	380,200
Obligations of U.S. states and municipalities
Concentration Risk [Line Items]
Trading securities	9,800	9,100
Available-for-sale securities	32,338	31,592
Held-to-maturity securities	14,373	14,475
Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	56,523	64,078
Consumer | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	1,143,709	1,113,718
On-balance sheet, Loans	522,192	506,460
Off-balance sheet	621,384	607,138
Consumer, excluding credit card
Concentration Risk [Line Items]
On-balance sheet, Loans	372,681	364,644
Consumer, excluding credit card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	421,234	417,891
On-balance sheet, Loans	372,681	364,644
Off-balance sheet	48,553	53,247
Consumer, Excluding Credit Card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	421,367	418,011
On-balance sheet, Loans	372,681	364,644
Off-balance sheet	48,553	53,247
Credit card
Concentration Risk [Line Items]
On-balance sheet, Loans	149,511	141,816
Credit card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	722,342	695,707
On-balance sheet, Loans	149,511	141,816
Off-balance sheet	572,831	553,891
Wholesale
Concentration Risk [Line Items]
On-balance sheet, Loans	408,505	388,305
Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	861,265	837,837
On-balance sheet, Loans	408,505	388,305
Off-balance sheet	370,098	368,014
Receivables from customers and other(a) | Consumer, Excluding Credit Card | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	133	120
Receivables from customers and other(a) | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	26,139	17,440
Wholesale-related | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	56,523	64,078
Wholesale-related | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	829,519	815,882
On-balance sheet, Loans	402,898	383,790
Off-balance sheet	370,098	368,014
Real Estate | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	153	207
Real Estate | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	139,409	134,287
On-balance sheet, Loans	113,648	105,802
Off-balance sheet	25,608	28,278
Consumer & Retail | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,114	1,082
Consumer & Retail | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	87,679	84,804
On-balance sheet, Loans	31,044	29,929
Off-balance sheet	55,521	53,793
Technology, Media & Telecommunications | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,265	1,293
Technology, Media & Telecommunications | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	59,274	63,324
On-balance sheet, Loans	13,665	14,063
Off-balance sheet	43,344	47,968
Healthcare | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,191	2,280
Healthcare | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	55,997	49,445
On-balance sheet, Loans	16,273	15,545
Off-balance sheet	37,533	31,620
Industrials | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,163	1,658
Industrials | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	55,272	55,733
On-balance sheet, Loans	18,161	17,295
Off-balance sheet	35,948	36,780
Banks & Finance Cos | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	6,816	12,257
Banks & Finance Cos | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	49,037	48,393
On-balance sheet, Loans	25,879	22,714
Off-balance sheet	16,342	13,422
Oil & Gas | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,727	1,878
Oil & Gas | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	41,317	40,367
On-balance sheet, Loans	12,621	13,253
Off-balance sheet	26,969	25,236
Asset Managers | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	7,998	10,820
Asset Managers | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	32,531	33,201
On-balance sheet, Loans	11,480	10,339
Off-balance sheet	13,053	12,042
Utilities | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,084	888
Utilities | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	29,317	29,672
On-balance sheet, Loans	6,187	7,208
Off-balance sheet	21,046	21,576
State & Municipal Govt | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,888	2,096
State & Municipal Govt | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	28,633	28,263
On-balance sheet, Loans	12,134	12,416
Off-balance sheet	13,611	13,751
Central Govt | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	13,937	14,235
Central Govt | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	19,182	20,408
On-balance sheet, Loans	3,375	3,964
Off-balance sheet	1,870	2,209
Chemicals & Plastics | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	208	271
Chemicals & Plastics | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	15,945	15,043
On-balance sheet, Loans	5,654	5,292
Off-balance sheet	10,083	9,480
Transportation | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	977	751
Transportation | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	15,797	19,096
On-balance sheet, Loans	6,733	8,996
Off-balance sheet	8,087	9,349
Automotive | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	342	1,196
Automotive | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	14,820	16,736
On-balance sheet, Loans	4,903	4,964
Off-balance sheet	9,575	10,576
Metals & Mining | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	702	439
Metals & Mining | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	14,171	13,419
On-balance sheet, Loans	4,728	4,350
Off-balance sheet	8,741	8,630
Insurance | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	2,804	3,382
Insurance | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	14,089	13,510
On-balance sheet, Loans	1,411	1,119
Off-balance sheet	9,874	9,009
Financial Markets Infrastructure | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	3,499	3,884
Financial Markets Infrastructure | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	5,036	8,732
On-balance sheet, Loans	351	347
Off-balance sheet	1,186	4,501
Securities Firms | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	1,692	1,913
Securities Firms | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	4,113	4,211
On-balance sheet, Loans	952	1,059
Off-balance sheet	1,469	1,239
All other | Credit Concentration Risk
Concentration Risk [Line Items]
On-balance sheet, Derivatives	3,963	3,548
All other | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	147,900	137,238
On-balance sheet, Loans	113,699	105,135
Off-balance sheet	30,238	28,555
Loans held-for-sale and loans at fair value | Wholesale | Credit Concentration Risk
Concentration Risk [Line Items]
Credit exposure	5,607	4,515
On-balance sheet, Loans	$ 5,607	$ 4,515