Investments - Schedule of Securities Pledged As Collateral For Repurchase Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 162,016	$ 131,422
AFS securities	148,347	112,225
Securities Sold under Agreements to Repurchase \| Asset Pledged as Collateral
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,659	6,161
AFS securities	4,071	4,996
Securities Sold under Agreements to Repurchase \| Asset Pledged as Collateral \| U.S. government and agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	2,559
AFS securities	0	1,941
Securities Sold under Agreements to Repurchase \| Asset Pledged as Collateral \| Foreign governments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	137	146
AFS securities	99	107
Securities Sold under Agreements to Repurchase \| Asset Pledged as Collateral \| Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,735	1,940
AFS securities	2,307	1,605
Securities Sold under Agreements to Repurchase \| Asset Pledged as Collateral \| CLO
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	580	273
AFS securities	579	261
Securities Sold under Agreements to Repurchase \| Asset Pledged as Collateral \| ABS
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,207	1,243
AFS securities	$ 1,086	$ 1,082