Investments - Schedule of Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net Investment Income:
Investment income, before expense	$ 771	$ 754	$ 2,102	$ 2,017
Investment expense	(82)	(64)	(228)	(171)
Net investment income	689	690	1,874	1,846
Fixed income securities
Net Investment Income:
Investment income, before expense	457	323	1,269	889
Equity securities
Net Investment Income:
Investment income, before expense	15	30	47	100
Mortgage loans
Net Investment Income:
Investment income, before expense	9	8	25	25
Limited partnership interests
Net Investment Income:
Investment income, before expense	190	325	446	841
Short-term investments
Net Investment Income:
Investment income, before expense	59	30	194	42
Other investments
Net Investment Income:
Investment income, before expense	$ 41	$ 38	$ 121	$ 120