Quarterly report pursuant to Section 13 or 15(d)

Credit Facility - Additional Information (Detail)

v3.3.0.814
Credit Facility - Additional Information (Detail) - USD ($)
 9 Months Ended
Sep. 30, 2015
Apr. 30, 2015
Dec. 31, 2014
Line of Credit Facility [Line Items]      
Credit facility outstanding $ 378,096,000   $ 315,748,000
Issuance costs $ 12,000,000    
Fees for loan agreement description Fees for each Loan Agreement equal to 0.50%, divided by 360, multiplied by the excess of the available borrowing capacity under each Loan Agreement over the actual amount borrowed under such Loan Agreement.    
Default underlying financings 50.00%    
Qualifying Government and Institutional Loans (G&I Facility) [Member]      
Line of Credit Facility [Line Items]      
Termination of credit facility Jul. 19, 2019    
Floating interest rate 1.50%    
Qualifying Project Finance Loans (PF Facility) [Member]      
Line of Credit Facility [Line Items]      
Termination of credit facility Jul. 19, 2019    
London Interbank Offered Rate LIBOR plus 2.5%    
Floating interest rate 2.50%    
Applicable valuation percentages 67.00%    
London Interbank Offered Rate (LIBOR) [Member] | Qualifying Government and Institutional Loans (G&I Facility) [Member]      
Line of Credit Facility [Line Items]      
London Interbank Offered Rate ("LIBOR") plus 1.5%    
Fixed interest rate 1.50%    
London Interbank Offered Rate (LIBOR) [Member] | Qualifying Government and Institutional Loans (G&I Facility) [Member] | 1.5% [Member]      
Line of Credit Facility [Line Items]      
Floating interest rate 1.00%    
London Interbank Offered Rate (LIBOR) [Member] | Qualifying Project Finance Loans (PF Facility) [Member]      
Line of Credit Facility [Line Items]      
Fixed interest rate 2.50%    
London Interbank Offered Rate (LIBOR) [Member] | Qualifying Project Finance Loans (PF Facility) [Member] | 1.5% [Member]      
Line of Credit Facility [Line Items]      
Floating interest rate 1.00%    
Federal Funds Effective Swap Rate [Member] | Qualifying Government and Institutional Loans (G&I Facility) [Member] | 1.5% [Member]      
Line of Credit Facility [Line Items]      
Floating interest rate 0.50%    
Federal Funds Effective Swap Rate [Member] | Qualifying Project Finance Loans (PF Facility) [Member]      
Line of Credit Facility [Line Items]      
London Interbank Offered Rate Federal Funds Rate plus 0.5%    
Federal Funds Effective Swap Rate [Member] | Qualifying Project Finance Loans (PF Facility) [Member] | 1.5% [Member]      
Line of Credit Facility [Line Items]      
Floating interest rate 0.50%    
Credit Default Option [Member] | Qualifying Government and Institutional Loans (G&I Facility) [Member]      
Line of Credit Facility [Line Items]      
London Interbank Offered Rate LIBOR plus 2.50%    
Floating interest rate 2.50%    
Credit Default Option [Member] | Qualifying Project Finance Loans (PF Facility) [Member]      
Line of Credit Facility [Line Items]      
London Interbank Offered Rate LIBOR plus 5.00%    
Floating interest rate 5.00%    
U.S. Federal Government [Member] | Qualifying Government and Institutional Loans (G&I Facility) [Member]      
Line of Credit Facility [Line Items]      
Applicable valuation percentages 85.00%    
Institutional [Member] | Qualifying Government and Institutional Loans (G&I Facility) [Member]      
Line of Credit Facility [Line Items]      
Applicable valuation percentages 80.00%    
Senior Secured Revolving Credit Facility [Member]      
Line of Credit Facility [Line Items]      
Maximum advances on credit facilities $ 1,500,000,000    
Senior Secured Revolving Credit Facility [Member] | Qualifying Government and Institutional Loans (G&I Facility) [Member]      
Line of Credit Facility [Line Items]      
Maximum advances on credit facilities 450,000,000    
Credit facility outstanding 150,000,000    
Senior Secured Revolving Credit Facility [Member] | Qualifying Project Finance Loans (PF Facility) [Member]      
Line of Credit Facility [Line Items]      
Maximum advances on credit facilities 1,050,000,000 $ 400,000,000  
Credit facility outstanding $ 350,000,000    
Senior Secured Revolving Credit Facility [Member] | Qualifying Project Finance Loans (PF Loan Agreement) [Member]      
Line of Credit Facility [Line Items]      
Maximum advances on credit facilities   $ 350,000,000