Insurance Liabilities - Discounting of reserves (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Discounting of Reserves [Line Items]
U.S. workers' compensation	$ 2,337,000,000	$ 2,532,000,000
Retroactive reinsurance	(1,104,000,000)	(1,254,000,000)
Total reserve discount	1,233,000,000	1,278,000,000
Fortitude RE
Discounting of Reserves [Line Items]
Total reserve discount	$ 687,000,000	$ 763,000,000
Discount ceded on sale (as a percent)	100.00%	100.00%
United Kingdom
Discounting of Reserves [Line Items]
Total reserve discount	$ 196,000,000	$ 135,000,000