Future Policy Benefits - Undiscounted Expected Gross Premiums and Expected Future Benefit Payments (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments, Undiscounted	$ 15,906		$ 13,819
Expected future gross premiums, Undiscounted	14,649		7,541
Expected future benefit payments, Discounted	8,103	$ 7,253	7,253	$ 6,618
Expected future gross premiums, Discounted	8,507		4,328
Annuity
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments, Undiscounted	5,531		3,466
Expected future gross premiums, Undiscounted	0		0
Expected future benefit payments, Discounted	3,384	2,213	2,213	1,288
Expected future gross premiums, Discounted	0		0
Life
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments, Undiscounted	10,375		10,353
Expected future gross premiums, Undiscounted	14,649		7,541
Expected future benefit payments, Discounted	4,719	$ 5,040	5,040	$ 5,330
Expected future gross premiums, Discounted	$ 8,507		$ 4,328