Investments - Components of net investment income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net Investment Income [Line Items]
Total investment income	$ 15,377	$ 12,418	$ 15,134
Investment expenses	785	651	522
Net investment income	14,592	11,767	14,612
Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	13,804	11,442	13,126
Investment expenses	756	618	485
Net investment income	13,048	10,824	12,641
Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	1,573	976	2,008
Investment expenses	29	33	37
Net investment income	1,544	943	1,971
Available for sale fixed maturity securities, including short-term investments
Net Investment Income [Line Items]
Total investment income	11,697	9,731	10,051
Available for sale fixed maturity securities, including short-term investments | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	10,780	8,664	8,583
Available for sale fixed maturity securities, including short-term investments | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	917	1,067	1,468
Other fixed maturity securities
Net Investment Income [Line Items]
Total investment income	382	(822)	(12)
Gains/(losses) recognized in earnings on hedging derivatives		(195)	(49)
Other fixed maturity securities | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	43	(363)	(19)
Other fixed maturity securities | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	339	(459)	7
Equity securities
Net Investment Income [Line Items]
Total investment income	94	(53)	(237)
Equity securities | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	94	(53)	(237)
Equity securities | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	0	0	0
Interest on mortgage and other loans
Net Investment Income [Line Items]
Total investment income	2,687	2,162	1,952
Interest on mortgage and other loans | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	2,450	1,959	1,745
Interest on mortgage and other loans | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	237	203	207
Alternative investments
Net Investment Income [Line Items]
Total investment income	319	989	2,900
Alternative investments | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	233	819	2,579
Alternative investments | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	86	170	321
Real estate
Net Investment Income [Line Items]
Total investment income	42	57	225
Real estate | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	42	57	225
Real estate | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	0	0	0
Other investments
Net Investment Income [Line Items]
Total investment income	156	354	255
Gains/(losses) recognized in earnings on hedging derivatives	(9)	186	65
Other investments | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	162	359	250
Other investments | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	$ (6)	$ (5)	$ 5