Investments - Schedule of Securities Pledged As Collateral For Repurchase Agreements (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 231,440	$ 228,168
Fair Value	219,474	218,644
Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,800	6,528
Fair Value	3,410	6,225
U.S. government and agencies \| Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	2,780
Fair Value	0	2,787
Foreign governments \| Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	259	241
Fair Value	185	185
Corporate \| Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,082	2,022
Fair Value	1,787	1,785
CLO \| Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	609	611
Fair Value	605	608
ABS \| Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	526	584
Fair Value	508	568
CMBS \| Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	231	197
Fair Value	231	198
RMBS \| Asset Pledged as Collateral \| Securities Sold under Agreements to Repurchase
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	93	93
Fair Value	$ 94	$ 94