Insurance Liabilities - Net loss reserve discount benefit (charge) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net Loss Reserve Discount Benefit (Charge) [Line Items]
Current accident year	$ 38	$ 24	$ 68	$ 48
Accretion and other adjustments to prior year discount	(54)	(38)	(148)	(42)
Net reserve discount benefit (charge)	(16)	(14)	(80)	6
Change in discount on loss reserves ceded under retroactive reinsurance	26	18	96	57
Net change in total reserve discount	10	4	16	63
United Kingdom
Net Loss Reserve Discount Benefit (Charge) [Line Items]
Net change in total reserve discount	$ 4	$ (7)	$ 8	$ (5)