Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.2
Derivative Instruments and Hedging Activities Schedule of Total Return Swaps (Details) - USD ($)
Sep. 30, 2020
Jun. 30, 2020
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Dec. 31, 2018
Derivative [Line Items]            
Notional $ 25,836,064,000 $ 8,076,933,000 $ 48,445,497,000 $ 54,226,205,000 $ 55,549,424,000 $ 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)