Annual report pursuant to Section 13 and 15(d)

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

v3.8.0.1
Fair Value Measurements - Summary of Fair Value and Carrying Value of Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Fair Value [Member] | Level 3 [Member] | Credit Facility [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities $ 70 $ 283
Fair Value [Member] | Level 3 [Member] | Non-recourse Debt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 1,239 718
Fair Value [Member] | Level 3 [Member] | Government Receivables [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 519 517
Fair Value [Member] | Level 3 [Member] | Commercial Receivables [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 464 500
Fair Value [Member] | Level 3 [Member] | Receivables Held For Sale [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 20  
Fair Value [Member] | Level 3 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 151 58
Fair Value [Member] | Level 3 [Member] | Securitization Residual Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 45 19
Fair Value [Member] | Fair Value, Inputs, Level 2 [Member] | Convertible Debt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 156  
Fair Value [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets   1
Carrying Value [Member] | Level 3 [Member] | Credit Facility [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 70 283
Carrying Value [Member] | Level 3 [Member] | Non-recourse Debt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities 1,238 709
Carrying Value [Member] | Level 3 [Member] | Government Receivables [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 519 526
Carrying Value [Member] | Level 3 [Member] | Commercial Receivables [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 473 516
Carrying Value [Member] | Level 3 [Member] | Receivables Held For Sale [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 19  
Carrying Value [Member] | Level 3 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 151 58
Carrying Value [Member] | Level 3 [Member] | Securitization Residual Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets 45 19
Carrying Value [Member] | Fair Value, Inputs, Level 2 [Member] | Convertible Debt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Liabilities $ 152  
Carrying Value [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets   $ 1