Reinsurance - Life Insurance Ceded Business (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Reinsurance for Insurance Companies, by Product Segment
Insurance losses and contract holders' benefits	$ 1,332	$ 1,418	$ 4,070	$ 3,772
Life Insurance Segment
Reinsurance for Insurance Companies, by Product Segment
Direct earned premiums	97	94	293	283
Ceded earned premiums	(21)	(19)	(60)	(57)
Earned premiums	76	75	233	226
Direct contract holders' benefits incurred	92	90	289	302
Ceded contract holders' benefits incurred	(21)	(20)	(59)	(74)
Insurance losses and contract holders' benefits	$ 71	$ 70	$ 230	$ 228