Investments - Schedule of Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net Investment Income [Line Items]
Investment income, before expense	$ 2,792	$ 2,649	$ 3,464
Investment expense	(314)	(246)	(171)
Net investment income	2,478	2,403	3,293
Fixed income securities
Net Investment Income [Line Items]
Investment income, before expense	1,761	1,255	1,148
Equity securities
Net Investment Income [Line Items]
Investment income, before expense	75	132	100
Mortgage loans
Net Investment Income [Line Items]
Investment income, before expense	35	33	43
Limited partnership interests
Net Investment Income [Line Items]
Investment income, before expense	499	985	1,973
Short-term investments
Net Investment Income [Line Items]
Investment income, before expense	253	82	5
Other investments
Net Investment Income [Line Items]
Investment income, before expense	$ 169	$ 162	$ 195