v3.25.1
Derivative and Other Hedging Instruments (Narrative) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Dec. 31, 2023
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net $ (1,011,000) $ 1,102,000    
Derivative assets, at fair value 98,000   $ 205,000  
Derivative liability, fair value (70,000)   (94,000)  
Interest Rate Swaption [Member]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net (19,000) 33,000    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period 1,500,000 0    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period (1,500,000) (1,250,000)    
Derivative, Notional Amount 2,000,000 0 2,000,000  
TBA and Forward Settling Agency Securities [Member]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net 77,000 (58,000)    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period 27,967,000 25,390,000    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period   (22,071,000)    
Derivative Asset, Fair Value, Gross Asset 7,473,000   6,861,000  
Derivative, Fair Value, Net 44,000   (26,000)  
Derivative, Notional Amount 7,811,000 8,651,000 6,955,000 $ 5,332,000
US Treasury Securities [Member]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net (100,000) 186,000    
Derivative, Fair Value, Net (38,000)   83,000  
Credit Default Swap, Buying Protection        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net   (3,000)    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period   0    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period   0    
SOFR Futures Contracts        
Derivative assets, at fair value 6,000   0  
Derivative, Notional Amount 1,200,000   1,200,000  
Derivative liability, fair value 0   (7,000)  
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member]        
Derivative, Notional Amount       1,250,000
Not Designated as Hedging Instrument [Member] | Credit Default Swap, Buying Protection        
Derivative, Notional Amount   96,000   96,000
Short [Member] | US Treasury Securities [Member]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net (460,000) 338,000    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period 3,821,000 3,101,000    
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period (3,977,000) (1,641,000)    
Derivative Asset, Fair Value, Gross Asset 1,822,000   4,886,000  
Derivative, Notional Amount 17,636,000 12,807,000 17,792,000 11,347,000
Long [Member] | US Treasury Securities [Member]        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net 60,000 (43,000)    
Trading Securities Added During the Period 5,388,000 1,669,000    
Notional Amount Of Trading Securities Settlement Expiration During The Period (3,757,000) (1,346,000)    
Debt Securities, Trading, and Equity Securities, FV-NI 3,216,000 1,815,000 $ 1,585,000 $ 1,492,000
Long [Member] | SOFR Futures Contracts        
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net $ 10,000 $ (10,000)