Fair Value of Short Term and Long Term Debt Excluding Capital Leases (Detail) - USD ($) $ in Millions |
Mar. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short- and long-term debt | $ 109,880 | $ 109,729 |
| Carrying Amount, Fair Value Disclosure | Excluding Capital Leases | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short- and long-term debt | 108,911 | 108,772 |
| Estimate of Fair Value Measurement | Excluding Capital Leases | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short- and long-term debt | $ 124,405 | $ 118,216 |