Quarterly report pursuant to Section 13 or 15(d)

Credit Facilities - Additional Information (Detail)

v3.7.0.1
Credit Facilities - Additional Information (Detail) - USD ($)
 3 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Line of Credit Facility [Line Items]    
Credit facility outstanding $ 406,487,000 $ 283,346,000
Unamortized issuance costs $ 6,000,000  
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 component of the credit facility over the actual amount borrowed under such component.  
Default underlying financings 50.00%  
Debt issuance cost $ 18,000,000  
Qualifying Project Finance Loans (PF Facility) [Member]    
Line of Credit Facility [Line Items]    
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%  
Floating interest rate 1.50%  
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 The 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%  
Base Rate [Member] | Qualifying Project Finance Loans (PF Facility) [Member]    
Line of Credit Facility [Line Items]    
Floating interest rate 0.00%  
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%  
Loans Payable [Member]    
Line of Credit Facility [Line Items]    
Maturity date Aug. 09, 2017  
Security provided for debt $ 128,000,000  
Additional interest rate on debt default 2.00%  
Debt issuance cost $ 1,400,000  
Loans Payable [Member] | Through April 9, 2017 [Member]    
Line of Credit Facility [Line Items]    
Short-term loans borrowed $ 102,000,000  
Loans Payable [Member] | London Interbank Offered Rate (LIBOR) [Member] | Through April 9, 2017 [Member]    
Line of Credit Facility [Line Items]    
London Interbank Offered Rate 3 month LIBOR plus 200 basis points  
Floating interest rate 2.00%  
Loans Payable [Member] | London Interbank Offered Rate (LIBOR) [Member] | April 9, 2017 [Member]    
Line of Credit Facility [Line Items]    
London Interbank Offered Rate 3 month LIBOR plus 275 basis points  
Floating interest rate 2.75%  
Loans Payable [Member] | Thereafter [Member]    
Line of Credit Facility [Line Items]    
Additional interest rate on debt default 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  
Credit facility outstanding $ 500,000,000  
Maturity month and year 2019-07