Fair Value Disclosures (Short-term and Long-term Borrowings) (Details) - USD ($) $ in Millions |
Mar. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short-term and long-term borrowing, fair value | $ 36,705 | $ 34,693 |
| Equity | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short-term and long-term borrowing, fair value | 19,006 | 17,789 |
| Interest Rates | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short-term and long-term borrowing, fair value | 15,657 | 14,255 |
| Credit and Foreign Exchange Contracts | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short-term and long-term borrowing, fair value | 1,704 | 2,266 |
| Commodities | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short-term and long-term borrowing, fair value | $ 338 | $ 383 |