Investments - Components of net investment income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Net Investment Income [Line Items]
Total investment income	$ 13,892	$ 12,993	$ 11,657
Investment expenses	768	765	579
Net investment income	13,124	12,228	11,078
Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	12,530	11,592	10,260
Investment expenses	738	734	550
Net investment income	11,792	10,858	9,710
Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	1,362	1,401	1,397
Investment expenses	30	31	29
Net investment income	1,332	1,370	1,368
Available-for-sale fixed maturity securities, including short-term investments
Net Investment Income [Line Items]
Total investment income	9,882	9,536	8,716
Available-for-sale fixed maturity securities, including short-term investments \| Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	9,210	8,796	7,894
Available-for-sale fixed maturity securities, including short-term investments \| Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	672	740	822
Other fixed maturity securities
Net Investment Income [Line Items]
Total investment income	463	369	340
Other fixed maturity securities \| Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	56	43	49
Other fixed maturity securities \| Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	407	326	291
Equity securities
Net Investment Income [Line Items]
Total investment income	86	4	40
Equity securities \| Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	86	4	40
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	2,889	2,678	2,359
Interest on mortgage and other loans \| Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	2,720	2,485	2,160
Interest on mortgage and other loans \| Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	169	193	199
Alternative investments
Net Investment Income [Line Items]
Total investment income	493	305	104
Alternative investments \| Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	378	159	18
Alternative investments \| Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	115	146	86
Real estate
Net Investment Income [Line Items]
Total investment income	31	41	38
Real estate \| Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	32	45	38
Real estate \| Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	(1)	(4)	0
Other investments
Net Investment Income [Line Items]
Total investment income	48	60	60
Other investments \| Excluding Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	48	60	61
Other investments \| Fortitude Re Funds Withheld Assets
Net Investment Income [Line Items]
Total investment income	$ 0	$ 0	$ (1)