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Income Taxes - Schedule of Components of Net Deferred Tax Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
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Income Tax Disclosure [Abstract] |  |  |  |
Deferred tax assets, Depreciation | $ 185 | $ 104 |  |
Deferred tax assets, Employee benefits | 2,499 | 2,742 |  |
Deferred tax assets, Loss provisions | 437 | 368 |  |
Deferred tax assets, Deferred income/expense | 87 | 53 |  |
Deferred tax assets, Tax loss carryforwards | 2,229 | 2,186 |  |
Deferred tax assets, Tax credit carryforwards | 567 | 508 |  |
Deferred tax assets, Derivatives and hedging activities | 74 | 117 |  |
Deferred tax assets, Other | 310 | 324 |  |
Deferred tax assets, Gross | 6,388 | 6,402 |  |
Deferred tax assets, Valuation allowance | (1,804) | (1,400) | (1,398) | (1,268)
Deferred tax assets, net | 4,584 | 5,002 |  |
Deferred tax liabilities, Depreciation | 1,150 | 1,015 |  |
Deferred tax liabilities, Employee benefits | 36 | 46 |  |
Deferred tax liabilities, Loss provisions | 14 | 17 |  |
Deferred tax liabilities, Deferred income/expense | 188 | 203 |  |
Deferred tax liabilities, Tax loss carryforwards |  |  |  |
Deferred tax liabilities, Tax credit carryforwards |  |  |  |
Deferred tax liabilities, Derivatives and hedging activities | 25 | 16 |  |
Deferred tax liabilities, Other | 261 | 297 |  |
Deferred tax liabilities, Gross | 1,674 | 1,594 |  |
Deferred tax liabilities, Valuation allowance |  |  |  |
Deferred tax liabilities, Net | $ 1,674 | $ 1,594 |  |

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