Fair Value Option - Structured Note Products by Balance Sheet Classification and Risk Component (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	$ 95,806	$ 80,724
Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	47,562	36,571
Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	4,665	5,004
Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	3,518	3,364
Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	38,170	34,172
Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	1,891	1,613
Long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	59,364	53,069
Long-term debt | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	27,338	24,137
Long-term debt | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	4,205	4,009
Long-term debt | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	3,368	3,169
Long-term debt | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	24,061	21,382
Long-term debt | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	392	372
Short-term borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	6,859	6,670
Short-term borrowings | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	95	62
Short-term borrowings | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	460	995
Short-term borrowings | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	112	157
Short-term borrowings | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	6,182	5,422
Short-term borrowings | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	10	34
Deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	29,583	20,985
Deposits | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	20,129	12,372
Deposits | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	0	0
Deposits | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	38	38
Deposits | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	7,927	7,368
Deposits | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total structured notes	$ 1,489	$ 1,207