Income Taxes - Net Deferred Tax Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets:
Deferred tax asset	$ (769)us-gaap_DeferredTaxAssetsNetCurrent	$ (134)us-gaap_DeferredTaxAssetsNetCurrent
Deferred charges and other	(17)us-gaap_DeferredCostsAndOtherAssets	(33)us-gaap_DeferredCostsAndOtherAssets
Liabilities
Other current liabilities	28	39
Deferred income taxes	9,499	8,364
Net deferred income tax liability	$ 8,741us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 8,236us-gaap_DeferredTaxAssetsLiabilitiesNet

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- Definition

Aggregate carrying amount of deferred costs and other assets not separately disclosed.

+ References

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- Definition

Carrying amount as of the balance sheet date of unearned revenue or income, not otherwise specified in the taxonomy, which is expected to be taken into income during the current period and current obligations not separately disclosed in the balance sheet (other liabilities, current).

+ References

No definition available.

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- Definition

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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- Definition

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards expected to be realized or consumed within one year or operating cycle, if longer.

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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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