Investment Information - Net investment income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net investment income:
Gross investment income		$ 386	$ 260	$ 736	$ 479
Investment expenses		(22)	(18)	(45)	(38)
Net investment income		364	242	691	441
Fixed maturities
Net investment income:
Gross investment income		306	214	586	402
Short-term investments
Net investment income:
Gross investment income		35	15	64	29
Equity securities
Net investment income:
Gross investment income		10	6	18	10
Other
Net investment income:
Gross investment income	[1]	$ 35	$ 25	$ 68	$ 38

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