v3.26.1
Derivative and Other Hedging Instruments (TBA Securities by Coupon and Issuer) (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Derivative [Line Items]            
Derivative liability, fair value $ (137)   $ (6)      
TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 10,047 $ 10,909 13,180 $ 8,407 $ 7,811 $ 6,955
Cost Basis 9,676   12,917      
Net long TBA position, at fair value 9,728   12,988      
TBA, net carrying value 52   71      
SOFR Futures Contracts            
Derivative [Line Items]            
Derivative, Notional Amount 2,600     $ 1,200    
Derivative liability, fair value (4)   0      
30 Year Maturity [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 9,780   13,032      
Cost Basis 9,406   12,766      
Net long TBA position, at fair value 9,459   12,837      
TBA, net carrying value 53   71      
30 Year Maturity [Member] | 6.5% Coupon | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 2,510          
Cost Basis 2,598          
Net long TBA position, at fair value 2,594          
TBA, net carrying value (4)   (3)      
30 Year Maturity [Member] | 5.5% Coupon | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 2,270   1,842      
Cost Basis 2,258   1,851      
Net long TBA position, at fair value 2,279   1,857      
TBA, net carrying value 21   6      
30 Year Maturity [Member] | 5.0% Coupon | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 2,061   5,679      
Cost Basis 2,019   5,643      
Net long TBA position, at fair value 2,031   5,666      
TBA, net carrying value 12   23      
30 Year Maturity [Member] | 3.0% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 2,295   0      
Cost Basis 1,933   0      
Net long TBA position, at fair value 1,950   0      
TBA, net carrying value 17   0      
30 Year Maturity [Member] | 3.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 0   452      
Cost Basis 0   415      
Net long TBA position, at fair value 0   417      
TBA, net carrying value 0   2      
30 Year Maturity [Member] | 4.0% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount     0      
Cost Basis     0      
Net long TBA position, at fair value     0      
TBA, net carrying value (1)   0      
30 Year Maturity [Member] | 4.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 908   5,317      
Cost Basis 862   5,156      
Net long TBA position, at fair value 871   5,193      
TBA, net carrying value 9   37      
30 Year Maturity [Member] | 6.0% Coupon | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount     1,745      
Cost Basis     1,780      
Net long TBA position, at fair value     1,786      
TBA, net carrying value (1)   6      
30 Year Maturity [Member] | Short [Member] | 6.5% Coupon | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount     2,003      
Cost Basis     2,079      
Net long TBA position, at fair value     2,082      
30 Year Maturity [Member] | Short [Member] | 4.0% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 50          
Cost Basis 46          
Net long TBA position, at fair value 47          
30 Year Maturity [Member] | Short [Member] | 6.0% Coupon | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 214          
Cost Basis 218          
Net long TBA position, at fair value 219          
15 Year Maturity [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 267   148      
Cost Basis 270   151      
Net long TBA position, at fair value 269   151      
TBA, net carrying value (1)   0      
15 Year Maturity [Member] | 4.5% Coupon [Member] | TBA and Forward Settling Agency Securities [Member]            
Derivative [Line Items]            
Derivative, Notional Amount 267   148      
Cost Basis 270   151      
Net long TBA position, at fair value 269   151      
TBA, net carrying value $ (1)   $ 0