Investments - Schedule of Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Net Investment Income [Line Items]
Investment income, before expense	$ 3,407	$ 2,792	$ 2,649
Investment expense	(315)	(314)	(246)
Net investment income	3,092	2,478	2,403
Fixed income securities
Net Investment Income [Line Items]
Investment income, before expense	2,298	1,761	1,255
Equity securities
Net Investment Income [Line Items]
Investment income, before expense	77	75	132
Mortgage loans
Net Investment Income [Line Items]
Investment income, before expense	36	35	33
Limited partnership interests
Net Investment Income [Line Items]
Investment income, before expense	600	499	985
Short-term investments
Net Investment Income [Line Items]
Investment income, before expense	290	253	82
Other investments
Net Investment Income [Line Items]
Investment income, before expense	$ 106	$ 169	$ 162