Quarterly report pursuant to Section 13 or 15(d)

Securitization of Receivables - Additional Information (Detail)

v3.8.0.1
Securitization of Receivables - Additional Information (Detail) - USD ($)
 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]      
Managed receivables $ 4,600,000,000   $ 3,900,000,000
Securitization credit losses 0 $ 0  
Asset-backed Securities, Securitized Loans and Receivables [Member]      
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]      
Managed receivables 2,500,000,000   $ 2,300,000,000
Greater than 90 Days Past Due [Member]      
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]      
Payment from debtors to securitization trust $ 1,800,000    
Minimum [Member]      
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]      
Discount rates to determine fair market value of underlying assets 4.00%    
Maximum [Member]      
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale [Line Items]      
Annual servicing fees 0.20%    
Discount rates to determine fair market value of underlying assets 7.00%