Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Schedule of Total Return Swaps (Details)

v3.20.1
Derivative Instruments and Hedging Activities Schedule of Total Return Swaps (Details) - USD ($)
Mar. 31, 2020
Dec. 31, 2019
Mar. 31, 2019
Dec. 31, 2018
Derivative [Line Items]        
Notional $ 60,549,307,000 $ 48,445,497,000 $ 58,777,783,000 $ 36,528,169,000
Markit IOS Total Return Swap [Member]        
Derivative [Line Items]        
Notional   41,890,000    
Fair Value   (29,000)    
Cost Basis   (59,000)    
Derivative, Unrealized Gains (Losses)   30,000    
Markit IOS Total Return Swap [Member] | Maturity Date, 1/12/2043 [Member]        
Derivative [Line Items]        
Notional   18,625,000    
Fair Value   5,000    
Cost Basis   (30,000)    
Derivative, Unrealized Gains (Losses)   35,000    
Markit IOS Total Return Swap [Member] | Maturity Date, 1/12/2044 [Member]        
Derivative [Line Items]        
Notional   23,265,000    
Fair Value   (34,000)    
Cost Basis   (29,000)    
Derivative, Unrealized Gains (Losses)   $ (5,000)