Commitments and Contingencies - Additional Information (Details) - Asbestos and Environmental - USD ($) $ in Millions	6 Months Ended	12 Months Ended	78 Months Ended
	Jun. 30, 2023	Dec. 31, 2016	Jun. 30, 2023
Loss Contingencies [Line Items]
Liability for unpaid losses and loss adjustment expenses, at undiscounted amounts	$ 327		$ 327
Reinsurance Contract [Axis]: Asbestos and Environmental
Loss Contingencies [Line Items]
Change in Deferred Gain on Retroactive Reinsurance	594		594
Reinsurance, Amount Retained, Per Policy		$ 1,700
Reinsurance Retention Policy, Excess Retention, Amount Reinsured			$ 1,244
Reinsurance Contract [Axis]: Asbestos and Environmental | Remaining [Member]
Loss Contingencies [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Policy	$ 256