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Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ (38)	$ (34)	$ (17)	$ (20)
RMBS | United States
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	(31)	(56)	(40)	(69)
RMBS | United States | First Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	(2)	(21)	(4)	(24)
RMBS | United States | Second Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ (29)	$ (35)	$ (36)	$ (45)

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