Insurance Liabilities - Discounting of Reserves (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Discounting of Reserves [Line Items]
U.S. workers' compensation	$ 2,206	$ 2,337
Retroactive reinsurance	(1,004)	(1,104)
Total reserve discount	1,202	1,233
Fortitude RE
Discounting of Reserves [Line Items]
Total reserve discount	$ 665	$ 687
Discount ceded on sale (as a percent)	100.00%	100.00%
United Kingdom
Discounting of Reserves [Line Items]
Total reserve discount	$ 197	$ 196