Quarterly report pursuant to Section 13 or 15(d)

Credit Facilities - Schedule of Limit of Borrowing at Any Point in Time and Total Maximum Advances (Detail)

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Credit Facilities - Schedule of Limit of Borrowing at Any Point in Time and Total Maximum Advances (Detail) - USD ($)
Jan. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Qualifying Government and Institutional Loans (G&I Facility) [Member]      
Line of Credit Facility [Line Items]      
Limit of Borrowing at any point in time $ 250,000,000 $ 150,000,000 $ 125,000,000
Maximum Total Advances 600,000,000 450,000,000 375,000,000
Qualifying Project Finance Loans (PF Facility) [Member]      
Line of Credit Facility [Line Items]      
Limit of Borrowing at any point in time 250,000,000 350,000,000 325,000,000
Maximum Total Advances $ 900,000,000 $ 1,050,000,000 $ 975,000,000