Fair Value of Short Term and Long Term Debt Excluding Capital Leases (Detail) - USD ($) $ in Millions |
Jun. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Estimate of Fair Value Measurement | Excluding Capital Leases | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short- and long-term debt | $ 127,281 | $ 117,584 |
| Carrying Amount, Fair Value Disclosure | ||
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||
| Short- and long-term debt | $ 116,537 | $ 107,128 |