Quarterly report pursuant to Section 13 or 15(d)

Nonrecourse Debt - Analysis of Nonrecourse Debt by Interest Rate (Parenthetical) (Detail)

v2.4.0.8
Nonrecourse Debt - Analysis of Nonrecourse Debt by Interest Rate (Parenthetical) (Detail)
Sep. 30, 2013
Dec. 31, 2012
Fixed-Rate Promissory Notes, Interest Rates from 2.06% to 5.00% Per Annum [Member] | Minimum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates 2.06%  
Fixed-Rate Promissory Notes, Interest Rates from 2.06% to 5.00% Per Annum [Member] | Maximum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates 5.00%  
Fixed-Rate Promissory Notes, Interest Rates from 2.26% to 5.00% Per Annum [Member] | Minimum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates   2.26%
Fixed-Rate Promissory Notes, Interest Rates from 2.26% to 5.00% Per Annum [Member] | Maximum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates   5.00%
Fixed-Rate Promissory Notes, Interest Rates from 5.01% to 6.50% Per Annum [Member] | Minimum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates 5.01% 5.01%
Fixed-Rate Promissory Notes, Interest Rates from 5.01% to 6.50% Per Annum [Member] | Maximum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates 6.50% 6.50%
Fixed-Rate Promissory Notes, Interest Rates from 6.51% to 8.00% Per Annum [Member] | Minimum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates 6.51% 6.51%
Fixed-Rate Promissory Notes, Interest Rates from 6.51% to 8.00% Per Annum [Member] | Maximum [Member]
   
Long Term Debt Maturity [Line Items]    
Fixed-rate promissory notes, interest rates 8.00% 8.00%