Quarterly report pursuant to Section 13 or 15(d)

Securitization of Receivables - Schedule of Fair Values of Retained Interests, Discount Rates Used in Valuing Interests (Detail)

v2.4.0.8
Securitization of Receivables - Schedule of Fair Values of Retained Interests, Discount Rates Used in Valuing Interests (Detail) (USD $)
6 Months Ended 12 Months Ended
Jun. 30, 2013
Dec. 31, 2012
Minimum [Member]
   
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Discount rate 8.00%  
Maximum [Member]
   
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Discount rate 10.00%  
Servicing [Member]
   
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Amortized cost basis $ 1,337,117 $ 1,592,369
Fair value 1,485,445 1,690,269
Weighted-average life in years 8 years 8 years
Discount rate 8.00% 8.00%
Fair value that would be decreased based on hypothetical adverse changes in discount rates:    
5% change in discount rate 285,484 306,920
10% change in discount rate 468,542 505,293
Residual Assets [Member]
   
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Amortized cost basis 4,251,852 4,366,437
Fair value 4,442,313 4,638,579
Fair value that would be decreased based on hypothetical adverse changes in discount rates:    
5% change in discount rate 1,185,242 1,220,186
10% change in discount rate $ 1,840,198 $ 1,883,844
Residual Assets [Member] | Minimum [Member]
   
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Weighted-average life in years 6 years 6 years
Discount rate 8.00% 8.00%
Residual Assets [Member] | Maximum [Member]
   
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Weighted-average life in years 17 years 17 years
Discount rate 10.00% 10.00%