Claim, Claim Adjustment Expense and Future Policy Benefit Reserves, Net Liability for Unpaid Claim and Claim Adjustment Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Liability for Unpaid Claim and Claim Adjustment Expenses [Abstract]
Net claim and claim adjustment expenses	$ 19,205	$ 18,701	$ 17,885	$ 17,965
Total reinsurance receivables	4,969	4,005	3,835	4,019
Total gross liability for unpaid claims and claims adjustment expenses	24,174	22,706	$ 21,720	$ 21,984
Property and casualty
Net Liability for Unpaid Claim and Claim Adjustment Expenses [Abstract]
Net claim and claim adjustment expenses	15,270	14,195
Total reinsurance receivables	2,333
Insurance, Other
Net Liability for Unpaid Claim and Claim Adjustment Expenses [Abstract]
Net claim and claim adjustment expenses	3,935	$ 4,506
Total reinsurance receivables	$ 2,636