Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Summary of Fair Value and Carrying Value of Financial Assets and Liabilities (Detail)

v2.4.1.9
Fair Value Measurements - Summary of Fair Value and Carrying Value of Financial Assets and Liabilities (Detail) (Fair Value, Measurements, Recurring [Member], Level 3 [Member], USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Fair Value [Member] | Credit Facility [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities $ 321us-gaap_LiabilitiesFairValueDisclosure
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$ 316us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_FairValueMeasurementsRecurringMember
Fair Value [Member] | Nonrecourse Debt [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 126us-gaap_LiabilitiesFairValueDisclosure
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127us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember
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= us-gaap_FairValueMeasurementsRecurringMember
Fair Value [Member] | Asset-Backed Nonrecourse Notes [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 210us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_FairValueMeasurementsRecurringMember
208us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember
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= us-gaap_FairValueMeasurementsRecurringMember
Fair Value [Member] | Financing Receivable [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 610us-gaap_AssetsFairValueDisclosure
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= us-gaap_FairValueMeasurementsRecurringMember
598us-gaap_AssetsFairValueDisclosure
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember
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= us-gaap_FairValueMeasurementsRecurringMember
Fair Value [Member] | Financing Receivables Held for Sale [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 40us-gaap_AssetsFairValueDisclosure
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62us-gaap_AssetsFairValueDisclosure
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Fair Value [Member] | Investments Available-for-Sale [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 23us-gaap_AssetsFairValueDisclosure
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27us-gaap_AssetsFairValueDisclosure
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Carrying Value [Member] | Credit Facility [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 321us-gaap_LiabilitiesFairValueDisclosure
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316us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_FairValueMeasurementsRecurringMember
Carrying Value [Member] | Nonrecourse Debt [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 111us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByLiabilityClassAxis
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/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
113us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_FairValueMeasurementsRecurringMember
Carrying Value [Member] | Asset-Backed Nonrecourse Notes [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 209us-gaap_LiabilitiesFairValueDisclosure
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/ us-gaap_FairValueByMeasurementFrequencyAxis
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208us-gaap_LiabilitiesFairValueDisclosure
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= us-gaap_FairValueMeasurementsRecurringMember
Carrying Value [Member] | Financing Receivable [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 554us-gaap_AssetsFairValueDisclosure
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553us-gaap_AssetsFairValueDisclosure
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Carrying Value [Member] | Financing Receivables Held for Sale [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 40us-gaap_AssetsFairValueDisclosure
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62us-gaap_AssetsFairValueDisclosure
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Carrying Value [Member] | Investments Available-for-Sale [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets $ 23us-gaap_AssetsFairValueDisclosure
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$ 27us-gaap_AssetsFairValueDisclosure
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