Annual report pursuant to Section 13 and 15(d)

Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Detail)

v3.6.0.2
Our Portfolio - Analysis of Portfolio by Type of Obligor and Credit Quality (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]    
Financing receivables $ 1,042,000  
Investments 58,058 $ 29,017
Real estate 172,000  
Equity method investments 363,297 $ 318,769
Total 1,635,000  
Average Remaining Balance 12,000  
Commercial Investment Grade [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing receivables 494,000  
Investments 20,000  
Real estate 172,000  
Total 686,000  
Average Remaining Balance 10,000  
Commercial Non-Investment Grade [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing receivables 22,000  
Total 22,000  
Average Remaining Balance $ 11,000  
Credit Concentration Risk [Member] | Commercial Investment Grade [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and Real Estate Portfolio 54.00%  
Credit Concentration Risk [Member] | Commercial Non-Investment Grade [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and Real Estate Portfolio 2.00%  
Government [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing receivables $ 526,000  
Investments 38,000  
Total 564,000  
Average Remaining Balance $ 12,000  
Government [Member] | Credit Concentration Risk [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and Real Estate Portfolio 44.00%  
Subtotal, Debt and Real Estate [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing receivables $ 1,042,000  
Investments 58,000  
Real estate 172,000  
Total 1,272,000  
Average Remaining Balance $ 11,000  
Subtotal, Debt and Real Estate [Member] | Credit Concentration Risk [Member] | Debt and Real Estate Portfolio [Member]    
Financing Receivable, Recorded Investment [Line Items]    
% of Debt and Real Estate Portfolio 100.00%  
Equity Method Investments [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Equity method investments $ 363,000  
Total 363,000  
Average Remaining Balance $ 19,000