Insurance Liabilities - Balances and Changes in Liability for Future Policy Benefits (Details) $ in Millions	6 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
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 changes in experience			$ (7)	$ (26)
Adjusted beginning of year balance	2,034	2,165
Issuances	54	67
Interest accrual	21	21
Net premium collected	(208)	(117)
Foreign exchange impact	(155)	(88)
Ending balance at original discount rate	1,746	2,048
Effect of changes in discount rate assumptions (AOCI)	(246)	(330)
Balance, end of period	1,500	1,718
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	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)	$ (16)
Adjusted beginning of year balance	2,582	2,726
Issuances	56	70
Interest accrual	26	26
Benefit payments	(212)	(122)
Foreign exchange impact	(203)	(121)
Ending balance at original discount rate	2,249	2,579
Effect of changes in discount rate assumptions (AOCI)	(329)	(423)
Ending balance	1,920	2,156
Net liability for future policy benefits, end of period	420	438
Deferred profit liability	1	1
Other reconciling items	934	963
Future policy benefits for life and accident and health insurance contracts	1,355	1,402	1,467
Less: Reinsurance recoverable	(761)	(754)
Liability for future policy benefits, end of period, net of Reinsurance recoverable	$ 594	$ 648
Weighted average liability duration of the liability for future policy benefits (in years)	9 years	9 years 10 months 24 days
Long-Duration Insurance
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Other reconciling items	$ 724		$ 713
Ceded percentage	1		1