Long-duration Contracts - Schedule of Unobservable Inputs for Market Risk Benefits (Details) $ in Millions	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Market Risk Benefit [Line Items]
Market risk benefits, net	$ 4,612	$ 3,715	$ 4,089	$ 3,373
Minimum \| Nonperformance risk \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.004		0.005
Minimum \| Option budget \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.005		0.005
Minimum \| Surrender rate \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.037		0.033
Minimum \| Utilization rate \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.286		0.286
Maximum \| Nonperformance risk \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.010		0.012
Maximum \| Option budget \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.060		0.060
Maximum \| Surrender rate \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.079		0.070
Maximum \| Utilization rate \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.950		0.950
Weighted Average \| Nonperformance risk \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.009		0.011
Weighted Average \| Option budget \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.026		0.022
Weighted Average \| Surrender rate \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.052		0.045
Weighted Average \| Utilization rate \| Discounted cash flow
Market Risk Benefit [Line Items]
Market risk benefits, measurement input (as percent)	0.861		0.847