Investments - Schedule of Changes in Unrealized Appreciation (Depreciation) of Available for Sale Securities and Other Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	$ (1,202)	$ 5,005
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date
Net gains recognized during the period on equity securities and other investments	252	161
Less: Net gains recognized during the period on equity securities and other investments sold during the period	69	154
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	183	7
Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	(1,214)	5,005
Fixed maturity securities | Continuing Operations, Excluding Held-For-Sale
Debt Securities, Available-for-sale [Line Items]
Increase (decrease) in unrealized appreciation (depreciation) of investments	(1,214)	5,005
Equity securities
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date
Net gains recognized during the period on equity securities and other investments	99	51
Less: Net gains recognized during the period on equity securities and other investments sold during the period	67	153
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	32	(102)
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 recognized during the period on equity securities and other investments	153	110
Less: Net gains recognized during the period on equity securities and other investments sold during the period	2	1
Unrealized gains (losses) recognized during the reporting period on equity securities and other investments still held at the reporting date	$ 151	$ 109