Insurance Liabilities - Net Loss Reserve Discount Benefit (Charge) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net Loss Reserve Discount Benefit (Charge) [Line Items]
Current accident year	$ 20	$ 47	$ 86	$ 115
Accretion and other adjustments to prior year discount	(49)	(52)	(217)	(200)
Net reserve discount benefit (charge)	(29)	(5)	(131)	(85)
Change in discount on loss reserves ceded under retroactive reinsurance	22	24	100	120
Net change in total reserve discount	(7)	19	(31)	35
United Kingdom
Net Loss Reserve Discount Benefit (Charge) [Line Items]
Net change in total reserve discount	$ 1	$ 7	$ 1	$ 15