Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ (7)	$ 11
RMBS | United States
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	(3)	5
RMBS | United States | First Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	(1)	0
RMBS | United States | Second Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ (2)	$ 5