Future Policy Benefits - Summary Balances and Changes in the Present Value of Expected Net Premiums and Present Value of FPB (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	$ 7,636	$ 7,050
Traditional Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of year	722	797
Beginning balance at original discount rate	874	974
Effect of actual variances from expected experience		(2)	$ (1)
Balance adjusted for variances from expectation		872	973
Interest accrual	9	19
Net premiums collected	(55)	(118)
Ending Balance at original discount rate	826	874
Effect of changes in discount rate assumptions	(160)	(152)
Balance, end of year	666	722
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of year	2,071	2,151
Beginning balance of original discount rate	2,492	2,665
Effect of actual variances from expected experience		58	(24)
Balance adjusted for variances from expectation		2,550	2,641
Interest accrual	27	56
Benefits payments	(108)	(205)
Ending Balance at original discount rate	2,469	2,492
Effect of changes in discount rate assumptions	(460)	(421)
Balance, end of year	2,009	2,071
Net liability for future policy benefits	1,343	1,349
Less: Reinsurance recoverable	524	413
Net liability for future policy benefits, after reinsurance recoverable	$ 819	$ 936
Weighted-average duration of liability for future policyholder benefits (years)	6 years 10 months 17 days	7 years 4 months 9 days
PRT
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of year	$ 4,189	$ 2,165
Beginning balance of original discount rate	4,351	2,475
Effect of changes in cash flow assumptions		5	(9)
Effect of actual variances from expected experience		(15)	(7)
Balance adjusted for variances from expectation		4,341	2,459
Issuances	952	2,041
Interest accrual	109	109
Benefits payments	(223)	(258)
Ending Balance at original discount rate	5,179	4,351
Effect of changes in discount rate assumptions	(310)	(162)
Balance, end of year	4,869	4,189
Net liability for future policy benefits	4,869	4,189
Less: Reinsurance recoverable	0	0
Net liability for future policy benefits, after reinsurance recoverable	$ 4,869	$ 4,189
Weighted-average duration of liability for future policyholder benefits (years)	7 years 9 months 7 days	8 years 2 months 23 days
Immediate annuities
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of year	$ 1,415	$ 1,429
Beginning balance of original discount rate	1,788	1,858
Effect of changes in cash flow assumptions		0	0
Effect of actual variances from expected experience		(21)	(15)
Balance adjusted for variances from expectation		1,767	$ 1,843
Issuances	18	22
Interest accrual	30	51
Benefits payments	(59)	(128)
Ending Balance at original discount rate	1,756	1,788
Effect of changes in discount rate assumptions	(431)	(373)
Balance, end of year	1,325	1,415
Net liability for future policy benefits	1,325	1,415
Less: Reinsurance recoverable	111	116
Net liability for future policy benefits, after reinsurance recoverable	$ 1,214	$ 1,299
Weighted-average duration of liability for future policyholder benefits (years)	11 years 9 months 14 days	12 years 5 months 19 days