Investments - Schedule of changes in unrealized appreciation (depreciation) of available for sale securities and other investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	$ (7,094)	$ (12,134)	$ (4,368)	$ (50,205)
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	143	(82)	534	265
Less: Net gains (losses) recognized during the period on equity securities and other investments sold during the period	17	39	175	96
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	126	(121)	359	169
Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	(7,033)	(12,134)	(3,962)	(50,205)
Fixed maturity securities | Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	(7,033)	(12,134)	(3,962)	(50,191)
Other investments | Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	0	0	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	41	16	135	(41)
Less: Net gains (losses) recognized during the period on equity securities and other investments sold during the period	19	26	159	119
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	22	(10)	(24)	(160)
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	102	(98)	399	306
Less: Net gains (losses) recognized during the period on equity securities and other investments sold during the period	(2)	13	16	(23)
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	$ 104	$ (111)	$ 383	$ 329