Insurance Premiums and Service Revenue (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Written
Direct	$ 476	$ 388	$ 397
Assumed	93	42	15
Gross insurance premiums	569	430	412
Earned
Direct	446	379	389
Assumed	68	29	8
Gross insurance premiums	514	408	397
Written
Ceded	(265)	(216)	(200)
Net insurance premiums	304	214	212
Earned
Ceded	(238)	(211)	(205)
Net insurance premiums	276	197	192
Service revenue	971	889	985
Service revenue	995	954	925
Insurance premiums and service revenue written	1,275	1,103	1,197
Insurance premiums and service revenue earned	$ 1,271	$ 1,151	$ 1,117

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