Investments - Net investment income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net Investment Income:
Investment income, before expense	$ 618	$ 1,015	$ 1,263	$ 1,760
Investment expense	(56)	(41)	(107)	(78)
Net investment income	562	974	1,156	1,682
Fixed income securities
Net Investment Income:
Investment income, before expense	299	290	566	591
Equity securities
Net Investment Income:
Investment income, before expense	34	13	70	27
Mortgage loans
Net Investment Income:
Investment income, before expense	9	12	17	22
Limited partnership interests
Net Investment Income:
Investment income, before expense	224	651	516	1,029
Short-term investments
Net Investment Income:
Investment income, before expense	10	1	12	2
Other investments
Net Investment Income:
Investment income, before expense	$ 42	$ 48	$ 82	$ 89