Investments - Net investment income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Net Investment Income:
Investment income, before expense	$ 754	$ 801	$ 2,017	$ 2,561
Investment expense	(64)	(37)	(171)	(115)
Net investment income	690	764	1,846	2,446
Fixed income securities
Net Investment Income:
Investment income, before expense	323	279	889	870
Equity securities
Net Investment Income:
Investment income, before expense	30	24	100	51
Mortgage loans
Net Investment Income:
Investment income, before expense	8	9	25	31
Limited partnership interests
Net Investment Income:
Investment income, before expense	325	438	841	1,467
Short-term investments
Net Investment Income:
Investment income, before expense	30	1	42	3
Other investments
Net Investment Income:
Investment income, before expense	$ 38	$ 50	$ 120	$ 139