v3.26.1
Derivative Instruments, Information of Treasury Futures Agreements (Details) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
U.S. Treasury Futures [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value $ (891) $ 1,368
U.S. Treasury Futures [Member] | 5 years [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value 59 (655)
U.S. Treasury Futures [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Fair Value [1] $ (950) 2,023
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 $ 128,100 171,200
Long Positions [Member] | U.S. Treasury Futures [Member] | 5 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount 111,500 171,200
Long Positions [Member] | U.S. Treasury Futures [Member] | 10 years [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount [1] 16,600 0
Short Positions [Member] | U.S. Treasury Futures [Member]    
Treasury Futures Agreements [Abstract]    
Net Notional Amount 99,700 151,700
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] $ 99,700 $ 151,700
[1] Includes 10-year Ultra futures and Long Bond futures contracts.