Investments - Credit Loss Expense Incurred (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Line Items]
Total credit loss benefit (expense)	$ (1)	$ (19)
Realized Gain (Loss)
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Line Items]
Total credit loss benefit (expense)	(2)	(17)
Corporate bonds
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Line Items]
Total credit loss benefit (expense)	(1)	(19)
Corporate bonds | Realized Gain (Loss)
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Line Items]
Total credit loss benefit (expense)	(2)	(18)
RMBS
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Line Items]
Total credit loss benefit (expense)	0	0
RMBS | Realized Gain (Loss)
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Line Items]
Total credit loss benefit (expense)	$ 0	$ 1