Reserve for Unpaid Losses and Loss Adjustment Expenses - PC Additional Information (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended	69 Months Ended
	May 23, 2019	Sep. 30, 2022	Dec. 31, 2016	Sep. 30, 2022	Dec. 31, 2021
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for Claims and Claims Adjustment Expense		$ 40,601		$ 40,601	$ 39,659
Reinsurance Recoverables, Gross		6,749		6,749	$ 6,622
Abuse Claims | General Liability [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for Claims and Claims Adjustment Expense		787		787
Reinsurance Contract [Axis]: Adverse Development Cover Navigators Group
Liability for Claims and Claims Adjustment Expense [Line Items]
Payments for Reinsurance	$ 91
Change in Deferred Gain on Retroactive Reinsurance		209		209
Reinsurance Recoverables, Gross		300		300
Reinsurance Contract [Axis]: Adverse Development Cover Navigators Group | Retention Layer for Reserve for the Covered Liabilities as of the Inception Date [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Reinsurance, Amount Retained, Per Policy		1,816
Reinsurance Contract [Axis]: Adverse Development Cover Navigators Group | Retention Layer Above Reserve for the Covered Liabilities as of the Inception Date [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Reinsurance, Amount Retained, Per Policy		100
Reinsurance Contract [Axis]: Asbestos and Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Payments for Reinsurance			$ 650
Reinsurance, Amount Retained, Per Policy			$ 1,700
Reinsurance Contract [Axis]: Asbestos and Environmental | Asbestos and Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Policyholder Benefits and Claims Incurred, Assumed				1,015
Change in Deferred Gain on Retroactive Reinsurance		365		$ 365
Reinsurance Contract [Axis]: Asbestos and Environmental | Remaining [Member] | Asbestos and Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Policy		485
Maximum | Reinsurance Contract [Axis]: Adverse Development Cover Navigators Group
Liability for Claims and Claims Adjustment Expense [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Policy		300
Maximum | Reinsurance Contract [Axis]: Asbestos and Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Reinsurance, Excess Retention, Amount Reinsured, Per Policy		$ 1,500