Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ (15)	$ (7)
RMBS | United States
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	(3)	(3)
RMBS | United States | First Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	2	(1)
RMBS | United States | Second Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ (5)	$ (2)