Reinsurance - Allowance for Credit Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	$ (10)	$ (20)
Provision for losses	(11)	10
Charge offs	0	0
Balance at End of Period	$ (21)	$ (10)