Investments - Components of net investment income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net Investment Income [Line Items]
Total investment income	$ 3,737	$ 2,819	$ 11,249	$ 8,988
Investment expenses	181	151	589	479
Net investment income	3,556	2,668	10,660	8,509
Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	3,465	2,656	10,225	8,328
Investment expenses	173	143	566	453
Net investment income	3,292	2,513	9,659	7,875
Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	272	163	1,024	660
Investment expenses	8	8	23	26
Net investment income	264	155	1,001	634
Available for sale fixed maturity securities, including short-term investments
Net Investment Income [Line Items]
Total investment income	2,918	2,406	8,568	7,162
Available for sale fixed maturity securities, including short-term investments | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	2,697	2,150	7,872	6,338
Available for sale fixed maturity securities, including short-term investments | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	221	256	696	824
Other fixed maturity securities
Net Investment Income [Line Items]
Total investment income	(39)	(241)	97	(915)
Gains/(losses) recognized in earnings on hedging derivatives		(57)		(208)
Other fixed maturity securities | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	(2)	(73)	18	(449)
Other fixed maturity securities | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	(37)	(168)	79	(466)
Equity securities
Net Investment Income [Line Items]
Total investment income	41	16	135	(41)
Equity securities | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	41	16	135	(41)
Equity securities | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	0	0	0	0
Interest on mortgage and other loans
Net Investment Income [Line Items]
Total investment income	692	568	2,001	1,578
Interest on mortgage and other loans | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	631	515	1,823	1,428
Interest on mortgage and other loans | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	61	53	178	150
Alternative investments
Net Investment Income [Line Items]
Total investment income	51	(38)	318	867
Alternative investments | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	26	(49)	249	729
Alternative investments | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	25	11	69	138
Real estate
Net Investment Income [Line Items]
Total investment income	8	14	28	46
Real estate | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	8	14	28	46
Real estate | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	0	0	0	0
Other investments
Net Investment Income [Line Items]
Total investment income	66	94	102	291
Gains/(losses) recognized in earnings on hedging derivatives	(1)	62	(5)	194
Other investments | Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	64	83	100	277
Other investments | Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	$ 2	$ 11	$ 2	$ 14