Investment Information - Net investment income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net investment income:
Gross investment income		$ 422	$ 289	$ 1,158	$ 768
Investment expenses		(23)	(20)	(68)	(58)
Net investment income		399	269	1,090	710
Fixed maturities
Net investment income:
Gross investment income		340	243	926	645
Short-term investments
Net investment income:
Gross investment income		38	19	102	48
Equity securities
Net investment income:
Gross investment income		9	5	27	15
Other
Net investment income:
Gross investment income	[1]	$ 35	$ 22	$ 103	$ 60

[1] Amounts include dividends and other distributions on investment funds, term loan investments, funds held balances, cash balances and other items.