Long-duration Contracts - Schedule of Expected Value for Expected Net Premiums and Future Policy Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Present value of expected future policy benefits
Interest accrual	$ 471	$ 346
Benefit payments	(1,145)	(885)
Net future policy benefits	51,672	42,490
Total
Present value of expected net premiums
Beginning balance	1,182
Effect of changes in discount rate assumptions, beginning balance	(45)
Liability For Future Policy Benefit, Expected Net Premium, Foreign Exchange Discount Rate Assumption	(2)
Ending balance at original discount rate	1,011		$ 1,135
Interest accrual	6
Net premium collected	(53)
Foreign exchange	(77)
Liability For Future Policy Benefit, Expected Net Premium, Foreign Exchange Discount Rate Assumption	(1)
Effect of changes in discount rate assumptions, ending balance	43
Ending balance	1,053
Present value of expected future policy benefits
Beginning balance	48,372	36,422
Effect of changes in discount rate assumptions	6,144	8,425
Effect of foreign exchange on the change in discount rate assumptions	(5)	(13)
Beginning balance at original discount rate	54,511	44,834
Effect of actual to expected experience			(8)	$ (29)
Adjusted balance			54,503	44,805
Issuances	42	88
Interest accrual	471	346
Benefit payments	(1,145)	(885)
Foreign exchange	(232)	14
Ending balance at original discount rate	53,639
Ending balance at original discount rate		44,368
Effect of changes in discount rate assumptions	(6,949)	7,623
Effect of foreign exchange on the change in discount rate assumptions	1	(7)
Ending balance	46,691	36,752
Net future policy benefits	45,638	36,752
Payout Annuities with Life Contingencies
Present value of expected net premiums
Beginning balance	0
Effect of changes in discount rate assumptions, beginning balance	0
Liability For Future Policy Benefit, Expected Net Premium, Foreign Exchange Discount Rate Assumption	0
Ending balance at original discount rate	0		0
Interest accrual	0
Net premium collected	0
Foreign exchange	0
Liability For Future Policy Benefit, Expected Net Premium, Foreign Exchange Discount Rate Assumption	0
Effect of changes in discount rate assumptions, ending balance	0
Ending balance	0
Present value of expected future policy benefits
Beginning balance	45,001	36,422
Effect of changes in discount rate assumptions	6,233	8,425
Effect of foreign exchange on the change in discount rate assumptions	1	(13)
Beginning balance at original discount rate	51,235	44,834
Effect of actual to expected experience			(4)	(29)
Adjusted balance			51,231	44,805
Issuances	42	88
Interest accrual	453
Benefit payments	(1,126)	(885)
Foreign exchange	(7)	14
Ending balance at original discount rate	50,593
Ending balance at original discount rate		44,368
Effect of changes in discount rate assumptions	(6,999)	7,623
Effect of foreign exchange on the change in discount rate assumptions	2	(7)
Ending balance	43,596	36,752
Net future policy benefits	$ 43,596	$ 36,752
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Weighted-average liability duration (in years)	9 years 6 months	10 years 1 month 6 days
Weighted-average interest accretion rate	3.70%	3.20%
Weighted-average current discount rate	5.40%	5.30%
Expected future gross premiums, undiscounted	$ 0
Expected future gross premiums, discounted	0
Expected future benefit payments, undiscounted	74,239	$ 63,995
Whole Life
Present value of expected net premiums
Beginning balance	1,182
Effect of changes in discount rate assumptions, beginning balance	(45)
Liability For Future Policy Benefit, Expected Net Premium, Foreign Exchange Discount Rate Assumption	(2)
Ending balance at original discount rate	1,011		1,135
Interest accrual	6
Net premium collected	(53)
Foreign exchange	(77)
Liability For Future Policy Benefit, Expected Net Premium, Foreign Exchange Discount Rate Assumption	(1)
Effect of changes in discount rate assumptions, ending balance	43
Ending balance	1,053
Present value of expected future policy benefits
Beginning balance	3,371	0
Effect of changes in discount rate assumptions	(89)	0
Effect of foreign exchange on the change in discount rate assumptions	(6)	0
Beginning balance at original discount rate	3,276	0
Effect of actual to expected experience			(4)	0
Adjusted balance			$ 3,272	$ 0
Issuances	0	0
Interest accrual	18	0
Benefit payments	(19)	0
Foreign exchange	(225)	0
Ending balance at original discount rate	3,046
Ending balance at original discount rate		0
Effect of changes in discount rate assumptions	50	0
Effect of foreign exchange on the change in discount rate assumptions	(1)	0
Ending balance	3,095	0
Net future policy benefits	$ 2,042	$ 0
Liability for Future Policy Benefit, after Reinsurance [Abstract]
Weighted-average liability duration (in years)	32 years 8 months 12 days	0 years
Weighted-average interest accretion rate	4.80%	0.00%
Weighted-average current discount rate	4.40%	0.00%
Expected future gross premiums, undiscounted	$ 1,344
Expected future gross premiums, discounted	1,103
Expected future benefit payments, undiscounted	$ 11,449	$ 0