Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ 11	$ (44)
RMBS | United States
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	5	7
RMBS | United States | First Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	0	18
RMBS | United States | Second Lien
Schedule of Expected Losses to be Paid [Line Items]
RMBS losses	$ 5	$ (11)