Reinsurance - Life Insurance Ceded Business (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Reinsurance for Insurance Companies, by Product Segment
Insurance losses and contract holders' benefits	$ 1,349	$ 1,398
Life Insurance Segment
Reinsurance for Insurance Companies, by Product Segment
Direct earned premiums	99	96
Ceded earned premiums	(20)	(19)
Earned premiums	79	77
Direct contract holders' benefits incurred	94	97
Ceded contract holders' benefits incurred	(15)	(16)
Insurance losses and contract holders' benefits	$ 79	$ 81