v2.4.1.9
Taxes - Additional Information (Detail) (USD $)
In Billions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Taxes [Line Items]      
Effective income tax rate 21.70%us-gaap_EffectiveIncomeTaxRateContinuingOperations 19.60%us-gaap_EffectiveIncomeTaxRateContinuingOperations (6.70%)us-gaap_EffectiveIncomeTaxRateContinuingOperations
Undistributed earnings of our foreign subsidiaries $ 1.3us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings    
Net tax loss and credit carry forwards (tax effected) 2.3us-gaap_DeferredTaxAssetsOperatingLossCarryforwards    
Net tax loss and credit carry forwards (tax effected), portion that will expire between 2015 and 2034 1.8us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration    
Operating loss carry forwards amount 0.5us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration    
Increase in valuation allowance 0.2us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease    
Unrecognized tax benefits, that if recognized, would favorably affect the effective income tax rate $ 1.3us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate $ 1.4us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate $ 2.1us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate