Fair Value Option - Structured note products by balance sheet classification and risk component (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	$ 57,656	$ 51,928
Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	20,776	15,929
Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	3,492	3,742
Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	2,506	1,853
Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	28,546	27,733
Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	2,336	2,671
Long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	37,247	32,424
Long-term debt | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	16,296	12,531
Long-term debt | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	3,267	3,195
Long-term debt | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	2,365	1,765
Long-term debt | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	14,831	14,293
Long-term debt | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	488	640
Other borrowed funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	8,815	9,179
Other borrowed funds | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	184	58
Other borrowed funds | Credit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	225	547
Other borrowed funds | Foreign exchange
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	135	77
Other borrowed funds | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	8,234	8,447
Other borrowed funds | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	37	50
Deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	11,594	10,325
Deposits | Interest rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	4,296	3,340
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	6	11
Deposits | Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	5,481	4,993
Deposits | Commodity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Structured notes balance	$ 1,811	$ 1,981