Fair Value Option - Structured note products by balance sheet classification and risk component (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	$ 55,093	$ 52,829
Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	14,639	13,437
Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	4,771	4,473
Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	1,662	2,378
Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	30,461	29,175
Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	3,560	3,366
Long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	30,631	30,089
Long-term debt | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	10,580	10,858
Long-term debt | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	4,353	4,023
Long-term debt | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	1,454	2,150
Long-term debt | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	13,416	12,348
Long-term debt | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	828	710
Other borrowed funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	13,242	14,177
Other borrowed funds | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	99	460
Other borrowed funds | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	418	450
Other borrowed funds | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	196	211
Other borrowed funds | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	12,300	12,412
Other borrowed funds | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	229	644
Deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	11,220	8,563
Deposits | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	3,960	2,119
Deposits | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	0	0
Deposits | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	12	17
Deposits | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	4,745	4,415
Deposits | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	$ 2,503	$ 2,012