Investments - Schedule of changes in unrealized appreciation (depreciation) of available for sale securities and other investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	$ (2,279)	$ (17,904)	$ 2,726	$ (38,071)
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date
Net gains (losses) recognized during the period on equity securities and other investments	230	(101)	391	347
Less: Net gains (losses) recognized during the period on equity securities and other investments sold during the period	4	(34)	158	57
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	226	(67)	233	290
Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	(1,934)	(17,904)	3,071	(38,071)
Fixed maturity securities | Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	(1,934)	(17,897)	3,071	(38,057)
Other investments | Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments		(7)	0	(14)
Equity securities
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date
Net gains (losses) recognized during the period on equity securities and other investments	43	(30)	94	(57)
Less: Net gains (losses) recognized during the period on equity securities and other investments sold during the period	(13)	(1)	140	93
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	56	(29)	(46)	(150)
Other invested assets
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date
Net gains (losses) recognized during the period on equity securities and other investments	187	(71)	297	404
Less: Net gains (losses) recognized during the period on equity securities and other investments sold during the period	17	(33)	18	(36)
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	$ 170	$ (38)	$ 279	$ 440