Insurance Liabilities - Balances and Changes in Liability for Future Policy Benefits (Details) $ in Millions	9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Present value of expected net premiums
Balance, beginning of year	$ 1,702	$ 1,929
Effect of changes in discount rate assumptions (AOCI)	339	262
Beginning balance at original discount rate	2,041	2,191
Effect of actual variances from expected experience			$ (7)	$ (44)
Adjusted beginning of year balance	2,034	2,147
Issuances	75	100
Interest accrual	22	22
Net premium collected	(268)	(160)
Foreign exchange impact	(87)	(62)
Other	0	(63)
Ending balance at original discount rate	1,776	1,984
Effect of changes in discount rate assumptions (AOCI)	(193)	(354)
Balance, end of period	1,583	1,630
Present value of expected future policy benefits
Balance, beginning of year	2,149	2,380
Effect of changes in discount rate assumptions (AOCI)	441	362
Beginning balance at original discount rate	2,590	2,742
Effect of actual variances from expected experience			(8)	$ (43)
Adjusted beginning of year balance	2,582	2,699
Issuances	79	104
Interest accrual	27	27
Benefit payments	(273)	(153)
Foreign exchange impact	(107)	(93)
Other		(74)
Ending balance at original discount rate	2,308	2,510
Effect of changes in discount rate assumptions (AOCI)	(264)	(461)
Balance, end of period	2,044	2,049
Net liability for future policy benefits, end of period	461	419
Deferred profit liability	1	1
Other reconciling items	1,009	891
Future policy benefits	1,471	1,311	1,467
Less: Reinsurance recoverable	(813)	(712)
Net liability for future policy benefits after reinsurance recoverable	$ 658	$ 599
Weighted average liability duration of the liability for future policy benefits (in years)	9 years 9 months 18 days	9 years 6 months
Long-Duration Insurance
Present value of expected future policy benefits
Other reconciling items	$ 776		$ 661
Ceded percentage	1		1