| **Tax Matters - Reconciliation of Gross Unrecognized Tax Benefits (Parenthetical) (Detail) (USD $)In Millions, unless otherwise specified** | Dec. 31, 2013 | Dec. 31, 2012 |
|---------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Income Tax Contingency [Line Items]**                                                                                                     |          |          |
| Income taxes payable                                                                                                                        | $ 678         | $ 979         |
| Noncurrent deferred tax liabilities                                                                                                         | 25,590        | 21,193        |
| Unrecognized Tax Benefit [Member]                                                                                                           |          |          |
| **Income Tax Contingency [Line Items]**                                                                                                     |          |          |
| Income taxes payable                                                                                                                        | 51            | 36            |
| Taxes and other current assets                                                                                                              | 63            | 30            |
| Taxes and other noncurrent assets                                                                                                           | 241           | 169           |
| Noncurrent deferred tax liabilities                                                                                                         | 2,300         | 231           |
| Other taxes payable                                                                                                                         | $ 3,400       | $ 5,800       |

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Carrying amount as of the balance sheet date of the unpaid sum of the known and estimated amounts payable to satisfy all domestic and foreign income tax obligations due beyond one year or the operating cycle, whichever is longer. Alternate captions include income taxes payable, noncurrent.
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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and other assets expected to be realized or consumed within one year or normal operating cycle, if longer.
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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and other assets expected to be realized or consumed after one year or normal operating cycle, if longer.
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| - Definition
Amount of deferred tax liability attributable to taxable temporary differences, net of deferred tax asset attributable to deductible temporary differences and carryforwards net of valuation allowances expected to be realized or consumed after one year (or the normal operating cycle, if longer).
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| - Definition
Carrying value as of the balance sheet date of obligations incurred and payable for statutory income, sales, use, payroll, excise, real, property and other taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).
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