Reserve for Property and Casualty Insurance Claims and Claims Expense - Reconciliation of the net incurred and paid claims development (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	$ 28,365
ULAE	1,649
Recoverables	9,176	$ 9,479	$ 7,033	$ 6,912
ULAE	126
Gross reserve for property and casualty insurance claims and claims expense	37,541	$ 33,060	$ 27,610	$ 27,712
Auto insurance - liability coverage
Claims Development [Line Items]
Net outstanding liabilities	17,382
Auto insurance - liability coverage | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	17,382
Recoverables	7,214
Auto insurance - physical damage coverage
Claims Development [Line Items]
Net outstanding liabilities	1,040
Auto insurance - physical damage coverage | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	1,040
Recoverables	44
Homeowners insurance
Claims Development [Line Items]
Net outstanding liabilities	3,459
Homeowners insurance | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	3,459
Recoverables	666
Other personal lines | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	1,558
Recoverables	320
Commercial lines | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	1,857
Recoverables	292
Protection Services | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	36
Recoverables	11
Run-off Property-Liability
Claims Development [Line Items]
Gross reserve for property and casualty insurance claims and claims expense	765
Run-off Property-Liability | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	1,370
Recoverables	503
Other | Property and casualty
Claims Development [Line Items]
Net outstanding liabilities	$ 14