Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ 87	$ (72)	$ 147	$ (148)
RMBS | United States
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	(48)	(95)	(52)	(127)
RMBS | United States | First Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	(12)	(38)	(12)	(34)
RMBS | United States | Second Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ (36)	$ (57)	$ (40)	$ (93)