v3.25.4
Derivative Instruments, Information of Treasury Futures Agreements (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
U.S. Treasury Futures [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value $ 1,368 $ 2,337
U.S. Treasury Futures [Member] | 5 years [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value (655) (1,226)
U.S. Treasury Futures [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value [1] $ 2,023 3,641
U.S. Treasury Futures Options [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value   33
U.S. Treasury Futures Options [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value   33
Ultra Futures Contracts [Member]    
Treasury Futures Agreements [Abstract]    
Future agreement period 10 years  
Long Bond Futures Contracts [Member]    
Treasury Futures Agreements [Abstract]    
Future agreement period 10 years  
Long Positions [Member] | U.S. Treasury Futures [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount $ 171,200 278,100
Long Positions [Member] | U.S. Treasury Futures [Member] | 2 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount [1]   108,600
Fair Value [1]   (78)
Long Positions [Member] | U.S. Treasury Futures [Member] | 5 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount 171,200 169,500
Long Positions [Member] | U.S. Treasury Futures [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount [1] 0 0
Long Positions [Member] | U.S. Treasury Futures Options [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount   60,000
Long Positions [Member] | U.S. Treasury Futures Options [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount   60,000
Short Positions [Member] | U.S. Treasury Futures [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount 151,700 205,000
Short Positions [Member] | U.S. Treasury Futures [Member] | 2 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount [1]   0
Short Positions [Member] | U.S. Treasury Futures [Member] | 5 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount 0 0
Short Positions [Member] | U.S. Treasury Futures [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount [1] $ 151,700 205,000
Short Positions [Member] | U.S. Treasury Futures Options [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount   60,000
Short Positions [Member] | U.S. Treasury Futures Options [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount   $ 60,000
[1] Includes 10-year Ultra futures and Long Bond futures contracts.